*THE HULL TRUTH is the world's largest FREE network for the discussion of Boating & Fishing. Whether you're researching a new boat, or are a seasoned Captain, you'll find The Hull Truth Boating & Fishing Message Forum contains a wealth of information from Boaters and Sportfishermen around the world.
Welcome to the updated THT!
If you are having trouble signing in, please email feedback@thehulltruth.com with your username and we will help you. We thank you for your patience as we help you access the new site!
Random Quote: Its better to apologize than ask permission
It all started late last September.running back to the dock WOT the engine with out warning went from 5600 rpm'ds down to a walk and than right back up to 5600 rpm's.my buddy on board thought i had pulled the throttle back ,but i hadnt.we noticed that when ever i crossed a boat wake at that speed the same thing would happen.so naturally i told the mechanic at the marina and he blamed it on the Ethanol causing gunk or water to be freed up and getting fouled somewhere in the engine causing this intermittent problem.now at the end of the year just before layup i filled my 139 gallon tank and but in Startron and Stabil and whatever else the yard said that i needed.i was suppose to go into the water 3/15/07 but because the yard had a problem with a collapsed seawall and my change of anchor pulpit i did not get into the water till 6/9/07.when i finally took the boat out the problem still existed,but now at lower speeds in rough water.the mechanic said i had too burn off my full tank of gas before i saw a difference.so i took the boat out again and was running at slow speeds,the prop spun off.the same machanic said that i must of hit something ,I HAD NOT,and when the marina owner looked over his bill that he sent me during the winter he realized that they had taken off the prop and probably did not put it back on correctly.they picked up that bill,but all i asked for was what i lost a SS yamaha prop,what they put on is a SS apollo.back to the original problem it has only gotten worse .this cracker jack machanic said now that the bulb on the gas line was sucKng in air do too a pinholeso he replaced the bulb took the boat out for a test drive and the problem was still there.so now he took the boat out on a 5 gallon spare tank with its own hose and he said the motor ran perfect at all speeds so he deduced that the check valve in my gas tank was clogged.he changed the whole fuel supply system from the tank to the gas filter evenstrawhat goes down into the tank.he ran the engine again,the problem is still there,so than he changed the line from the gas filter to the engine and before he tested the boat he told me"it has too work now there is nothing left too change" well you guessed it the problem is still there.he also opened the gas tank and looked inside with a flashlight and said the tank was in very good condition ,no flaking it looked real good,the problem is still there.this is a motor that for 5 years never hiccupped,the boat has only run very well and all of a sudden this.my best friend a retired machine engine (not marine engines) says to me that with his trained ear the engine is running perfectly even in between problems.if it wasn't for the sea trial on the 5 gallon can i would have thought it to be the engine,maybe the o2 sensor or a fulty fuel pump but i'm told it ran perfectly,WHAT DO YOU CAPTAINS THINK TYHEV PROBLEM COULD BE ?ALSO SHOULD I INSIST ON THE YAMAHA SS PROP OR SETTLE FOR THIS APOLLO PROP THAT ONLY GETS THE ENGINE UP TO 54OO RPMS INSTEAD OF THE 5600 TO 5800 THAT THE MGFR SAYS IT SHOULD BE PUTTING OUT,oh by the way this mechanic said that this is a better prop for the engine because it keeps the engine from reving too high and this is better for an older engine.well this older engine only has 287 ours on it.also shoud i be made to pay for this new fuel hosing and man hours even though hge didnt fix anything.PLEASE RESPOND I HAVE NOT HAD 1 GOOD DAY OIN THE WATER THIS YEAR AND I'M NOT GETTING ANY YOUNGER
First off, did you go along with the mechanic when he used the portable tank? If not I would buy one and try it out myself.
If this solves the problem and you are positive about it then guess what your tank and lines are still the problem.
Otherwise a better discription of the motor would be in order as te next step.
First off, did you go along with the mechanic when he used the portable tank? If not I would buy one and try it out myself.
If this solves the problem and you are positive about it then guess what your tank and lines are still the problem.
Otherwise a better discription of the motor would be in order as te next step.
jenkinsph:no i was not on the boat when he test drove the boat with the spare tank but by telling me he got it up to 5400 rpms thats something it can't do with the main tank. the motor is as 2001 yamaha ox 2 stroke fuel injected with a seperate oil resivor
i don't thionk a 5 gallon tank is much of a saftey net on a 250hp motor.like using a hankercheif to jump out of a plane.its only going to give you 1 small run
Vinny, I believe that HotSpot was showing his aggreement with troubleshooting with an external portable gas tank.
I have heard of similiar problems being caused by trash or sediment in the fuel tank that intermittently blocks the fuel pickup screen causing fuel starvation. If the motor runs on the portable tank without problem, then then the culprit lies within your fuel supply system.
Your motor should operate at or very near the max RPM at WOT. Overpropping the motor is not a good thing as it can shorten the remaining life of the motor. The mechanics statement sounds too much like supporting the "boss." I would want a SUITABLE" replacement prop for the one that was spun off.
Well you could get a 12 gallon tank from Basspro or Cabelas wih hose for $80 plus fuel but you may be suprised how long the 250
would idle at say 1000 rpms keeping you headed into the wind or how far you could go at idle to get back to the dock.
Look at it this way, you have to know for sure whether it is an engine problem or a fuel tank problem and/or a mechanic problem.
I would use fresh gas from somewhere known to be dependable too. I assumed from your post that this problem comes up
right away when the tank is first sloshed around is this correct or is it more of an intermittent problem?
STEVE: whenever i put the key in the ignition to start the motor it starts first time every time ,i never even prime the bulb.i take the boat down a long canal about a mile at 4 mph ,my guess is this warms up the motor also.when i get to the spot where i can open it up i push the throttle foward to WOT and it immediately stalls.i restart the engine and increase trhr throttle slowly and it gets up to speed very nicely.as soon as i encounter a boat wake or choppy seas the engine decelerates and than accelerates.or if i am running at lets say 4300 rpm nice and smooth as i cross another boats wake the boat will drop down in rpm's to a walk and than go right back to where it was,and if i passed the boat wake it will be ok again till the next boat wake but if its choppy it will continue doing it until i bring the boat down to 5-7 mph and so far it hasn't done it at that speed.i just talked to my marina and they said they are bringing in an outside machanic they think maybe a new set of eyes may help.i just don't know what to do i'm at my wits end.this is supposed to be for fun and relaxation not for aggrevation and frustration,if i want aggrvation i can stay home and talk to my wife
mikie i hate too admit it but i know how to trade stocks i did that for 34 years and am now retired the boat on thre other hand i leave to professionals.he has changed all the hoses and the straw into the tank and said that i do not have an overflow vent persay but it is incorporated into the fill cap,he mentioned that he was checking into it but i dio not remember hearing what the outcome was except that whatever he did last did not work.just for the hell of it am i suppose to pay for all this experimental changing of hoses and such that don't do anything?
Well you still need to know which is it the fuel system or the motor and do you have a good fuel filtration system and if so
did you check the filters after the last trial run?
Troubleshooting is often a process of elimination if the end result is engine problems (inwhich the fuel system may have been
causal) do you want their mechanics to work on it or your dealer?
BTW, you may want to see if you can borrow a couple of tanks from your dealer to test this problem.
If the motor is having problems and bad fuel is the culprit you may be better served to have the dealer mechanic in your court.
From what you last described you could run out the end of the canal on your regular tank then plug in the portable tank and
throttle up fast, if you still have the problem then the engine is the culprit. I am betting the trash has worked its way down
the line to the engine but you need to know for sure.
As Mike mentioned about venting, just loosen the fuel cap, and listen for air rushing in the tank, if you leave it loose for a
minute and you still have problems then thats not it. Retighten the fuel tank cap.
Best bet is to run her on a spare tank. This will tell you if it's a motor or main tank issue and right now I am guessing it could be either. It could be the screens on your carbs being clogged or the screen on the fuel pick up on the main tank. When you are idling not much is being stirred up but hammer it or hit a wake and the gas starts sloshing around and any junk in the system will clog the screens and stall your motor.
I'd also demand they give you a new Yamaha SS prop. Next step is to find a new mechanic.
Vinny, I had a very similar experience with my 1997 Yamaha. Out for a cruise, beautiful day, so I WOT. Suddenly I hear the alarm. Back and forth with the mechanic for the next month. Changed the water pump, oil pump, etc.
The same exact thing would happen when I hit a wave, the engine would kick into Safe mode. Extremely frustrating.
The mechanic eventually figured out that it was the electric control panel (or somthing like that). Anyway, he decribed it as the panel that all the wires ran (I know he dumbed it down for me, but since I am not a mechanic, that was fine). That part was replaced and I have not had a problem since (two years now. KNOCK ON WOOD!).
Just something else to look at or suggest to the mechanic.
thank you responders for all your good advice.a brother tht has a friend who is a certified yamaha machanic that owns his own dealership who is going to come to me a take a look at the problem.hopefully when this happens there goes the problem
vinny f
jenkinsph:no i was not on the boat when he test drove the boat with the spare tank but by telling me he got it up to 5400 rpms thats something it can't do with the main tank. the motor is as 2001 yamaha ox 2 stroke fuel injected with a seperate oil resivor
To me it sounds as if it has to be an electrical issue. I had an issue where the boat would run great and I would idle down and it would shut off. Sometimes if it sat for a few min. it would start back up and sometimes it would take a day or so. Every time they looked at the motor it fired right up making it hard to find the problem. Finally it went down for good and my buddy was able to trace it down.
vinnyf,
Several years ago I had a Merc 225 that developed similar problems. Erratic response, seemed to be a fuel clogging problem they couldn't find. Finally I had to idle in from about 30 miles. Only then they were able to find a small crack in one of the solid state electronic components. Your wake crossing description reminded me of the Merc's problem antics.
BOAT OR MOTOR PROBLEM 
