Boating How-To’s - Runs great for about an hour, then runs pretty rough!

It is a 18' 1985 Sun Runner with a 140 HP 3 liter 4 cyl. Merc I/O on 95%+ fresh gas (vs. old gas). I just bought the boat a month ago and have not had great luck with a boat that the seller says "everything works" and the 15-20 minute on-water run/test went well.

I have replaced the Tach which pegs as soon as the ignition was turned on(seller showed me this and said it was a connection issue, but a new tach works just fine). Replaced the VHF radio (bad handset connector) and compass (lost its fluid). The fish/depth finder is likely next as it reads anything only sporadically...but if she won't run for more than a hour without coughing and spitting why have the boat:( .

The previous owner replaced the cap, wires, and plugs (I have the old ones) and changed the oil all last summer/fall and had it winterized (late?) last fall. He says he is not familiar with this issue on this boat, and has been of a very tiny bit of insight at best post-sale. Right now, I am about to tell him off and leave the boat in his front lawn:(

We have taken her out 5 times and EVERY time she has gone out like a charm and about an hour later (cruising &/or idling/no-waking) she starts to run rough and comes in like a she wants crutches. She will sputter, start to purr nicely and then almost sound like she out of gas (the tach just flickers right with the sound of the coughing/sputtering engine). Even with the rough running, she'll hold RPM's somewhere in the upper-2000's to mid-3000's (bouncing between purring and sputtering) and hold somewhere in the mid-20's MPH (by GPS)...and if I want her to, she'd bounce in the upper 3000's to about 4k...again with a fairly wide range depending on how much she will sputter and cruise about 26-28 MPH.

I previously thought it would only do this after idling for about 20 minutes. But our most recent run we got on the water, cruised about 3 or 4 miles and then let her idle/no-wake for 23-25 minutes (aprox 1-1.5 miles)...and then she still got up and ran great and cruised about 3100 rpm and even ran her WOT about 4200 RPM/25 MPH for a long moment or so. But after another 5 miles of 3000 cruising (about 60-70 minutes total) she just started to cough and spit and mis-fire...just like she had on previous runs after idling/no-waking for about 20-25 minutes after a 20-30 minute cruise). She even back fired a time or two when we were trying to make our way back to port/ramp. We were about 10 miles from port (the ramp) and she really didn't want to go. It sounded like she was only running on 2 or 3 of the 4 cyl.

She will NOT stall out, and if I shut her down, she will start up right about the same as a cold start...and she starts fairly easily when cold. The word picture I want to give is: imagine the sound of an air plane running out of gas...you hear it trying to run, but certainly not smoothly. Just we're a boat and in the water of course...

We started with a hair more than a half tank (31 gal. tank) we ended with just a hair over a 1/4 tank covering less than 20 miles. It might have been a hair under a half a tank when the problems started, the aprox hour out from the ramp. The temp gauge always reads a steady about 140-150 once she got warmed up which easily happened in the initial cruise mentioned above. Volts always reads a very steady over 12 as well. There are no flickers in the lights (dash, transom, or gauges). Until she starts to cough or such about an hour in, she runs quite well. Starts cold pretty easily.

The water was quite smooth...but we've also had this exact same problem on 1 foot and even on 1-2 foot waves vs. this almost glass-like night.

There are no obvious signs of electrical issues. It has dual batteries and we run it on both unless we shut her down and say fish or just enjoy the calm water. I did find out on this last time out that the #2 battery is not very strong...but the boat is quite happy at least on both (#1 & #2 together).

I've done a solid 'dry gas' treatment, no change. I also threw in a regular gas treatment (like STP) also no change. I've pulled the sending unit from the tank and the tank and fuel both look clean...as well as the fuel pickup tube.

Lots of info, more if needed...I welcome as much insight as I can. Been using the in-law's boat for the past 10-12 years and finally bought our own...and really wondering if that was a good idea or not....

My coil was breaking down. If you have duals, swap coils and see if problem goes with engine. Also make sure coil wire is not pressing up abainst anything metal. Mine was too. Good luck!

OK Lets not do anything rash. MAYBE the last owner did not have this issue. He may not have run the boat at WOT for an hour.
It sounds like you are running out of fuel. or at least the engine is. I would start by checking to see if the fuel tank vent is clear. Make sure no bugs (mud wasps, spiders ect) have taken up residence in the line. Or that no one has compounded or waxed the vent holes closed. (Like I once did. I was told "boat sure looked pretty being towed back in" and NO I wont do that again)
Another way to check is to take the boat out again and when it starts to act up simple have someone loosen the fuel cap. If the problem goes away start looking for a blockage or a pinched hose.
Please let us know how you make out.
Phil K.

Also, check the pick up tube on the tank. It could have a screen on it that gets clogged by stuff in the tank then settles again when you let it sit.

Nitz is 100% correct about stale gas causing crud in tank and clogging up tube!!!!!

Mud dobbers are a pain in the neck too, but crap sloshng around in tank will find the small hole in pick up tube. If so, you're in for some labor.

Thank you all of you for your insight and paitence.

Trying not to be rash but for a boat that "everything works" with a new interior and having replace a radio, compass, and Tach....likley the fish/depth finder and at least 1 (if not 2) of the batteries...plus a sometimes flakey I/O Lift...and then add this motor problem...it looks nice in our driveway, is mostly nice for about an hour on the water and is really no fun sipping beer in it while sitting in the driveway since we can't take it out. As my co-worker said this morning...I got blanked. And that is not getting any easier to swallow... i.e. the new interior is about all I got other than a seemingly solid hunk of fiberglass and roller trailer to put it on.

Tank, tank vent, fuel, fuel pick up tube/screen...all clear. I am not running her WOT much at all. I did for maybe a minute or so of that last run just to see what she will top out at since we finally had smooth enough water to find out and I brought the GPS to read it. Generally we cruise about 3000...3500 tops.

I will check the coils and wire to & fro...

I am torn if it is running rich or lean after the 1st hour...I am getting feedback in both directions. But, I am also aiming to check the fuel filter...as I have the old parts from the previous owner having done the plugs, cap and wires, but I also have a small (aprox quarter-/hafl-dollar-sized diamiter) fuel filter still in its package...not sure if it just didn't get changed or if it was not appicable to my motor.

Where is the fuel filter on this Merc 140 4 cyl.?

Suggestions on a good service manual for this motor?

Ignition.

Fuel pickup problem does not affect an engine instantly. Remember, there is enough fuel in the carb float bowl for it to run for up to a minute with NO fuel flow.

If you buy a used boat you quickly learn that BOAT actually means Bring On Another Thousand! You are not alone!

Your engine has old style points, in the distributor , so that's another place to look. They could be worn or gapped a little wide, causing it to have an ignition issue when they heat up. You can easily check them to see if they are 18-20, look at them for white color which would show they are worn and if nothing else just run some fine sand paper thru them to clean them up. Thats some free stuff to check and it sounds like everything was replaced except for them last year; its a very common thing to change them every year or two, especially in high humidity that causes moisture issues.

The best way to tell if the engine is running rich or lean is to look at the plugs. If the engine is running lean the plugs will almost look like they are new, if the engine is running rich the plugs will be covered in black soot. While you have them out make sure that they are gaped properly and that they are the proper ones. DON'T use cross over charts. Use the plug the manufacturer calls for.
After reading all of your posts again. you stated that the boat will run for approx 1 hour before it gives you any issues. In that hour you could be idling or running at cruise without issue until that hour is up. Idling uses less fuel than cruise so consumption is different but the time factor is the same. Right? Now I leaning toward electrical. Like jlang said, were the points changed or were they over looked. Look at the wires feeding the coil and the points, are they clean and tight. Are any of them getting green in color or are they green already? What is the voltage at the coil when it is running good? Is it the same as when it is acting up? It sounds as though something is building up resistance when the engine has been running for that hour. The running on 2 or 3 cyls could be due to lack of voltage.
I have seen some ignition systems start on 12 volts but run on 9. If you have a resistor wire or ballast going bad it may give you the same issues. Time seems to be the constant factor unless I'm misunderstanding you.
Try not to be too upset. Think of it as a learning lesson. Once you get it fixed you feel better being on the water knowing how well you know your boat.

Time IS the only consistent factor. I had a glance at the 1st & 2nd plug. They looked about the same...a little white (white ish...) I have a very simple 91 600 air-colled motor cyle...the 2 plugs I pulled looked about the same as what I see when I pull the motorcycl's plugs....and it runs pretty well.

I will continue to look more so at the ignition etc.... I hope to have some time to explore on Wed...been quite busy with work... After all...one does have to work to pay for their toys right...I am pretty sure that is right, and I know when I tried to dodge that bullet...the wife said I lost.

THANK YOU for your continued insight!!!!!!!! In the end, it WILL BE helpful!!!!!!!

caveat emptor...welcome to boating and buying anything used...

a fuel pump failure or fuel system sucking air are possible concerns also...

welcome to boat ownership...ever heard the saying "youre ready to buy a boat when you feel comfortable flushing $100 bills down the toilet."?...

Just one more thing to consider is to check the fuel line from the tank to the motor. Ethanol will eat the inside of the hose and cause it to collapse or partially block the fuel getting to the engine. Also check your fuel water separator and all the connections to make sure that your not sucking air at any of those. One way to really check it out is to get an external tank and hook it up, run the boat and see if the problem goes away.

Okay Yall...I finally got some free time and I dove in.

I did find the fuel filter. I checked it and the lines...filter not noticably dirty, but will replace. No sign of a fuel/water seperator...leaning towards adding one to the fuel system.

When I pulled the little cup that goes over my fuel filter, I did get a tiny bit of fuel leaking (seemingly what may have been in the cup). Keep in mind, that cup is domed on top and is sealed to the fuel system at the bottom... i.e. it is upside down.

On the lip of the cup it has a faint amount of corrosion/white chaulky stuff. But there is NEVER a smell of fuel on the boat, even all the way down into the bidge.

I checked the cap, rotor and such...nothing green, seemingly nothing but beautiful seemingly about brand new shiny parts.

The fuel line from tank to engine appears to be just fine. Firm, no sign or feel of it wanting to collapse or such.

I'm guessing I am now likely ruling out fuel problems, and leaning towards ignition...like coil or power pack...ay?

In my opinion, I think you have ruled out fuel. I think I would start to check into the power supply to the ignition as well as the grounds. Rule of thumb, esp on boats is to check ALL grounds first. By that I mean don't just look at them and see if they are tight, take the nut or bolt holding the wire to its ground point off and look at it. While it is off CLEAN it and when you put it back together put a good corrosion blocker on it. Does the wire look green? Bend it by the connector, does anything come out? dust? corrosion? Does it crunch when you bend it? Dose it bend easy like the wire is broken inside and there is only insulation. IF it does any of these things cut back the insulation and don't be surprised at what you find. Start looking at the connection from the battery cable to the block first then look at the rest of the connections.
Did the last owner take anything apart when the boat was winterized? Maybe a thermostat housing with a ground wire going to it? Maybe that wire got broken or not put back on.
When the boat acts up again get to a safe spot and anchor up. Shut the engine off.(You said in other post it always starts back up ) Open the engine cover and feel the ground and feed wires. If any of them feel warmer than the others pay close attention to that one first.
Please let us know what you find.
Good luck. Phil K.

Thank you for such the informative post. I won't be able to put her in the water again until at least Saturday evening...I can try to explore with your most recent wisdom then....I will post what I find out.

Assuming I do get her out Saturday evening...anything else I should be exploring? There was some mention of a power pack? I only have 1 thing that I see is going to the distributor cap and then goes to the plugs....forgive me for my ignorance...is that the power pack or coil?

would a dead (or dying) battery end up ticking off the alternator in about an hour?

There is almost no noise when started and when purring.

But there is a very quiet, but noticiable, ticking whcn she gets passed that aprox. 1 hour mark... And the last time we had her our...Bat. #1 is just dandy...but #2 appears to be just about dead.

I also had a similar problem with an inboard motor and replaced many parts with the same problem persisting. Finally fixed it with a new fuel filter with greater flow rate (bigger).
Worth a try - worked for me
Welcome to the world of boating, and hope you have better luck in the future.

Ok as others have stated. run it until it begins to falter. then remove engine cover.. feel of the grounds and feel the coil.. if the coil is smoking hot it is failing. To check to see if it is lean or rich. Pull the choke, if it gets better it is lean. if it changes to worse it was rich.
The battery issue? You say it cranks right back up. So evidently the one battery is still strong enough to turn it over?

Thank you everyone for you wisdom and a bit of patience with me as well.

I hope to take her out on Saturday evening and will explore with all this wisdom and report back once I do.

THANK YOU!!!!!!!!!!

Best when feeling the coil to check if it's hot, is to touch the coil's body, not that wire coming out the top - it bites if the motor is still running.
Only mentioned this as you seem to be just starting to learn about your boat engine.

Thank you:) I was thinking that might be the case...but I also had planned to shut her down when I went back there just to be safe. I have some mech. knowlege but I am also running blind at the moment as with my motorcycle, I have the service manual and I've had that same bike for 16 years....the boat, I've been on/using/some servicing to my in-lw's but they have an outboard and it was 99% just maintenance, not repair or diagnosis.

Hope to have more info on Saturday night.

P's

Coils are either internally or externally resisted. Often a non-resistor coil is used to replace a resistor coil, and the coil overheats. If indeed the coil is failing (which it sounds like), do not simply replace the coil with what's there now without checking for the proper application.

Okay...I am about to share with you fine and patience (and even wise) folks...some very techinical terms...

YIPPY! We got her out on the water...We didn't go very far from the ramp as we are on the last 1/4 tank and didn't want to either get stuck out there or add another variable.

We did a little cruising, a lot of idling and at least some waking (not idle but just under planing...making a fairly good wake). We were out there for about an hour and 40-45 minutes. The curve ball...she really did NOT act up (insert a yippy/head-scratch combo here).

She DID flicker a tiny TINY bit about 1:15-1:20 into the night. but the tach did NOT bounce and the engine only (at most) had a little seemed like it missed a fire a couple times in about 10-15 seconds. Give it throttle...she purred right up. The only (somewhat) tangible thing that did show up slowly was a little bit of a ticking sound very directly in line with the engine speed...it was and hasn't been there at the begining of ANY runs; further into ALL of the runs (tonight too) there is this ticking sound that we've learned fades into the picture as it prepares (and does) run rough.

The technical terms: When we got back to port...I'm sorry tos ay I only checked the coild temp, no other ground wires or such. (I'm a slacker. I perfer ineffectively efficient) The coild was around the same temp as the wire, the cap was definetly cooler, almost just warm, most certainly NOT hot. Coild vs. oil filter...filter was almost a scald, could was a hot potato but I could keep my fingers on...like a hot shower temp but not scalding.

The only thing different tonight (the only known variable)...A: we didn't not cruise much at all B: the AM/FM radio was off, and C: I had played with cyl. #2 wire that the plug had come off on the cap-end, I put the old #2 wire on and replaced the cap-end 'connector' that is under the rubber boot on the cap.

Same run-time and then some
Same idles for a while as with previous runs
Same remains of this tank of fuel
Same fairly smooth waters

Was this all the failing (then 100% failed) #2 cyl. plug wire that was partially fixed with an old wire and now seemingly properly fixed with the new wire...

May take her out again on Sunday but will actually fill the tank up entirely...likey just boring 87...thoughts on the octane? I know in-law's 19 w/ 60HP Johnson OB ran better and got clearly noticably better 'mileage' on premium (lower 'cost-per-mile' on prem. 93)....

That ticking sound could possibly be a high voltage arc to ground. The only way to find out is to run it until it starts then using either a mechanics stethescope or piece of tubing held to your ear move the other end around slowly until it gets louder. It could also be the points that was mentioned earlier.

Do you have any tools such as a timing light? I found on my engine that I was only running on 3 cylinders by moving the clamp around to the different spark plug wires. The power pack went bad and stopped firing #1 cylinder. I would suggest getting a manual for your engine. It will help during tune ups and troubleshooting. I knew nothing about outboard engines 8 months ago. Now I know a tiny bit, but I have rebuilt my carbs, replaced the water pump, changed the lower end lube, fixed the Tilt and Trim leak, synchronized and timed the carbs, timing, and idle. I also know that I have 115 psi compression across all 4 cylinders, and replaced the power pack. Everything but the power pack is considered maintainence.

The points are inside the cap right? Everything inside the cap, as well as the cap and the wires were brand new last fall from the previous owner...and I have the old parts that came of from that being done.

it appears that 'maintenance' is a little more than I had hoped for and something I have to learn to do.

Engine Manual is supposed to be on its way to me. Still trying to find an outdrive manual for it.

No timing light but I have access to a mech steth. May play with it some this week to further explore that tick and confirm which cylinder (s) are having trouble. I'm guessing there is some special (and likey expensive) tool to confirm compression?

In your first post you stated that when it acted up it felt like the engine was running on 2 or 3 of the 4 cyls. In your last post you stated the ONLY thing that you changed was to repair the #2 spark plug wire.If the wire was loose or not connected properly it will cause the coil to work harder (won't go into detail as to why) to jump both the air gap of the plug AND the air gap of the the unattached wire. causing the coil to get hot and possibly not function properly.
As far as the ticking sound Dave may be correct. Was the ticking sound still there after you corrected the wire issue? I'm a little confused on this point. Please keep us posted Phil K.

Ticking...
it was there each run...including the last run on Saturday. But it hasn't shown up til later in the run...it seems to be an indicator the rough running was coming. Althought on saturday night, she really did NOT run rough...but the ticking did show up...and pretty much right on time, about an hour on the water.

What was done...
on various runs, #2 cyl. was originally on the 'new' wire as it came with the boat...I checked some of the stuff from previous different post and found that poor/bad connection. I put back on one of the old wires the seller left with me and it still happened.

Saturday was on the only run with the repaired 'new wire' (took off the 'old' wire). That was the only variable that was different on that run (Saturday) other than we did mostly idling with a few spots of planing and cruising (vs. 50 plane / 50 idle) and the AM/FM stereo was left off (vs. turning it on).

It seem, and I don't 100% for sure yet, but by what happened on Saturday's run:

The majority of the rough running appears to have been due to the failing and then busted connector on the cap-end of the 'new' #2 wire. The same symptom seemed to happen with the 'old' #2 wire I temperariliy used. With the repaired 'new' #2 wire...it seemed to be running pretty well even 1:30- almost 1:50.

Thank you for the continued patience, interest in helping and of course your wisdom!!!

You'll need a compression tester to check that. Some auto parts stores will loan specialty tools out or you can buy one for less than $40. But don't worry about that right now, though. Just curious, can you tell if the plug wires are automotive or marine? If you can run the engine exposed at nightin the dark, even on a garden hose and flusher you may see the sparks jumping to ground IF that is what it is. Just one more 'free' diagnostic technique...

Yep. The 'new' ones are say "something or other Marine" like brand name then marine. The 'old' ones the seller left with me (and the old cap, rotor etc.) I can't tell on them.

Thanks for the insight on the copression tool and the arking at night! GOOD THINKING!!!

Real quick...I am very low on fuel and about to fill the tank...tonight or tomorrow...suggestions on grade of gas? Brand?

Grade: On my in-law's I swore by 93 (prem.) as it started easier, ran better and got better milage, thus, lower fuel cost per mile. Our older Tahoe we used to do that with but not on our Trailblazer or our Cross Country...better performance but really no better milage. Would that make an improvement on this boat 'milage'?

I am thinking Marathon as they at least used to be no ethenoal? And I also was linked to I think puregas.org or such to find other stations that don't use ethenal. I found a HUGE difference on Marathon Gas vs. speedway (super america) or even Shell's gas.

Ethanol sucks. but get used to it if Obama is reelected. Ticking might be exhaust leak, but to know if it is electrical for certain, run motor at night and wiggle wires. If arching, you will see it and maybe feel it!!!!!!!:o If wires are orginal, replace!!!!! If coil is not hot, I'd still bet on clogged pick-up tube, once trash moves around in tank and collects there. If you can, remove screen inside tube and rely on filter to clean crap. Ethanol has really cause problems for boats that sit for months. We had similar problem as to yours, which was loose electrical connection AND pickup tube screen getting clogged. My probems manifested only after getting into bay or choppy water, where stuff was wiggled loose from bottom of tank. You can buy electrical rubber gloves which will keep you from getting the hell shocked out of you while examining your wires. I suggest purchasing a pair. I did. Oh, ticking may be lifter or rocker arm too loose. As motor heats and expands, gaps widen. If you havn't already done so, pull dist. cap and examine rotor for cracks and green coorsion on any tips. I had rotor short out on an older point driven OMC. It took forever to find that defective part. Hang in there and good luck!!!!!

The best time to diagnose a secondary (high voltage) ignition problem is at night! If you have a defective wire or crossfire, it will light up..a plug wire will glow internally if it is bad.

"Course you can always just grab the wires and which ever one knocks you on yer butt is the bad one.......

Been there and done that toooooooooooooo!

Okay...Been a little while but finally got her out again...and no surprise, only continued disapointment...she acted up again just about the same. It only took about 45 minutes when I took her out solo in early Thursday afternoon and then only about 25 minutes later that night with the wife and a freind. For the afternoon solo ride, she didn't run too bad, but she 100% DID act up and it varied how 'bad' it was. It was worse and then a little not too bad and then worse and so on. For the evening ride, she was fairly steady in running poorly...it did vary a little, but mostly it got bad and went slowly further bad. The only up side on either run, it didn't seem to get quite so bad...the tach didn't bounce too much, there wasn't hardly any on the solo ride and only a little at the tail end of the evening ride that it really would sputter bad and vary the engine speed (there weren't too many serious 'coughs' where it would really struggle to hold 3000 RPM).

I have a full tank of fresh gas. I cleaned up and put 'no-ox' on the coil and cap connections. I put a brand new fuel filter on the fuel pump and I added a 25 micron water-fuel seperator (will replace with 10 micron when they need to be replaced, 25's were half price).

I am now exploring the 'bad wire' or such but trying to line up smooth water with time to taker her out and look for that problem.

A tech at my work's garage who also does boat mechanics made a suggestion of checking the fuel pump. He said if it was going bad, it would end up dumping a lot more fuel into the system than it should normally (which makes some sense with my gas guage going down so fast when she runs rough). I will be trying to check on both of those and re-post those results once I can get either or both done.

Insight from here? Just change the coil? Make sure the 'resistor' is also changed?

The only thing that is consistent is it takes time to create the problem...would the fuel pump need to get warmed up before it would start to fail? Would a bad wire work fine to start but take time to start shorting out?

Okay...Been a little while but finally got her out again...and no surprise, only continued disapointment...she acted up again just about the same. It only took about 45 minutes when I took her out solo in early Thursday afternoon and then only about 25 minutes later that night with the wife and a freind. For the afternoon solo ride, she didn't run too bad, but she 100% DID act up and it varied how 'bad' it was. It was worse and then a little not too bad and then worse and so on. For the evening ride, she was fairly steady in running poorly...it did vary a little, but mostly it got bad and went slowly further bad. The only up side on either run, it didn't seem to get quite so bad...the tach didn't bounce too much, there wasn't hardly any on the solo ride and only a little at the tail end of the evening ride that it really would sputter bad and vary the engine speed (there weren't too many serious 'coughs' where it would really struggle to hold 3000 RPM).

I have a full tank of fresh gas. I cleaned up and put 'no-ox' on the coil and cap connections. I put a brand new fuel filter on the fuel pump and I added a 25 micron water-fuel seperator (will replace with 10 micron when they need to be replaced, 25's were half price).

I am now exploring the 'bad wire' or such but trying to line up smooth water with time to taker her out and look for that problem.

A tech at my work's garage who also does boat mechanics made a suggestion of checking the fuel pump. He said if it was going bad, it would end up dumping a lot more fuel into the system than it should normally (which makes some sense with my gas guage going down so fast when she runs rough). I will be trying to check on both of those and re-post those results once I can get either or both done.

Insight from here? Just change the coil? Make sure the 'resistor' is also changed?

The only thing that is consistent is it takes time to create the problem...would the fuel pump need to get warmed up before it would start to fail? Would a bad wire work fine to start but take time to start shorting out?

Try removing fuel pick up tubes, if you can, and remove wire screens, if you haven't already done so. Crap generated by ethonol will inevitably slosh around in tanks and settle near tube opening until pump sucks up into tube, and your motors will not run without gas. Screen packs up with crap and will not permit fuel to go through. Back at dock or trailering, the craps has a chance to work freely back into tank. Been here and found out the hard way. Make sure that you reinstall anti-suphon valves. Good luck!

If it is running rich the plugs would be black..lean they would be squeeky clean. Remember, you don't need constant fuel flow for a carburetor to work.

"Tach jumping" says it's primary ignition..the tach is a pulse counter. Bad condenser will do this.

To rule out any issues with the fuel tank, run off of a six gallon tank... Be sure to isolate the existing fuel supply altogether.

many years ago @18 maybe,I had a v6 175 Mercury outboard,that thing run as good as anything on the water for @30/45min.,an then it would not even get the boat on plane.took it to local Mercury mechanic an He put 2 new coils on,it has 6 total,an life was GOOD again.I think you can check the Coils with an OHM meter an see what the resistance is. That would be My suggestion as where to start..

many years ago @18 maybe,I had a v6 175 Mercury outboard,that thing run as good as anything on the water for @30/45min.,an then it would not even get the boat on plane.took it to local Mercury mechanic an He put 2 new coils on,it has 6 total,an life was GOOD again.I think you can check the Coils with an OHM meter an see what the resistance is. That would be My suggestion as where to start..

Different coils..outboards use a magneto. some have CDI units. In any case, not a points and coil set-up.

Your motor is an inboard, right ?
Your local car mechanic can find and fix the problem
Better than finally breaking down at sea and having to be towed home at night.
All replies to your post are possibly correct, but which one is, can only be found by trial and error, or by getting an expert with the experience and diagnostic tools to find the problem.
Boating is a learning experience so try to enjoy it.

The ticking noise, and the fact that this seems to be a thermal problem makes me wonder about the heads or the exhaust. I'm wondering if the engine just takes that long to get up to a temperature that causes something to stop working...like a sticking valve, or a crack in a head that opens up.

Great news but a small bump at the end:(

It was less than $50 and it took less than 15 minutes to install it...

It appears (and I stress a lack of 110% confirmation but I'm at about 99% sure) ....

This entire head ache...it was all caused by a bad coil! I replaced the coil on Thursday and finally got a chance to take her out tonight (Sunday) and after an hour and 40 minutes with trying to make it 'act up' ...I could not...at all!

Yippy! but again, only about 3/4's yippy...

At the ramp we were taking her out of the water...and when lifting the outdrive...the motor for raising and lowering the drive did its normal flicker (mostly on the way up but now and then going down too)...on the way up.

Except...when as I got the drive most or all the way up the motor kept clicking/ticking a tiny bit slowly...even though I let go of the button...even after I pushed the down button, it sounded like it was still trying to go up:(

A really smelly smoke filled most of the engine compartment...and I shut the battery switch off...the top of the lift-motor/pump assembly (the motor is on top right?) was pretty hot the bottom, not hardly warm.

I did not see any burnt wires but I also only lifted the sundeck cushions and peaked in as the really stinky cloud came out...

Thoughts on where to start with the newest headache?

Great news...It appears...it was all caused by a bad coil! Too bad no one suggested checking the coil in the first response to this thread (http://www.thehulltruth.com/4743396-post2.html) :grin:

Tipsy

On the upside...I now know a heck of a lot more about my boat, including a bunch of stuff that currently is in just dandy condition and not causing any problems. And I also added a water/fuel separator that I may have eventually added but did right now hoping to help the issue at hand.

Further...the trim issue appears to be just a failing up selenoid and that will be both cheaper and closer to pick up from also being in stock like the coil was. Hope to have her up and running nicely before noon tomorrow!

THANK YOU to all of you that provided insight, wisdom and gave me a great education on my vessel!!!!!

This is a EXTREAMELY valuable site!!!!!!!