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Random Quote: Ignorance can be fixed, stupid is permanent.
I have twin 2001 225's one of which is not running very well. I have read all the posts I could that looked similar to my problem and I think the throttle position sensor may be the culprit but I would like to see if you all think I am on the right track. The powerheads were replaced w/new factory powerheads in 2004 and all the updates have been performed (as far as I know, according to the dealer who sold them to me)
Unfortunately something isn't wired quite right with the warning horn...it never comes on. It doesn't sound on start up and I have had the engine go into guardian mode without ever getting the horn so right now that is of no help. Not sure what the problem is but I imagine has something to do with repowering from 1993 200's to these without changing the harness? Anyway....
When I first start the engine it revs to 3000 rpm then settles down to 600 but it idles very rough and stalls pretty quickly, surging between 550 and 650 rpm.
If I rev it in neutral say to 1600 RPM, it will surge down to 1200 then back up, as low as 1000 then back to 1600.
At higher RPM under a load, I noticed when I was running home the other day, it would go from 4800 down to 4400 and every 20 secs or so it would momentarily surge back to 4800. When this occured, I tried to get WOT but only got 5000 instead of 5400 like usual.
I pulled the plugs and they didn't look terrible but one was substantially more fouled than the others. I put in all new plugs, no change. With the engine idling, I pulled the wire on the plug that was fouled and the engine stalled immediately so I know that the coil is doing something.
I changed the fuel water sep, no change.
The fuel from the sep was clean, no water and no debris. I also have fuel/water seps prior to the engine which were recently changed as well (50hrs ago)
I checked the belt/tensioner and I still have a little travel left, no different than the other engine so I kind of doubt it is the problem.
Should I replace the throttle position sensor(s) or just get it hooked up to the diagnostic? My neighbor has the DDT and only charges $65.... thoughts?
Aside for any re-rigging issues, it sounds like a fuel pressure issue... I am not sure if you have the EFI or Opti's, but if you have the EFI's I would clean the final filter at the base of the fuel pump. It is a pain, but can be done if you are mechanically inclined. You can check the TPS easily with a voltmeter, my value if memory serves me correctly, was .95 + or - ohms at idle and I think 3.80 + or - ohms at WOT, with the key on and motor off.
If it has never been right since the re-rig, than that could the root of all your problems, the deal from the neighbor could make life easy for you, and take out a lot of troubleshooting. Keep us posted on how you make out.
__________________
-Scarab Sport Twin Merc 250
-GP1200 -WV1100 Waverunners
-A Bunch of Motorcycles
Surging is usually associated with water in fuel on boats. If you are drawing off 2 tanks, this would be a possiblity.
One of the benefits of twins, if you suspect a bad component, you can switch with the other motor and see if the problem moves to the other motor or not.
A standard DMM and a service manual can help you test most of the components without the need for the dealers DDT to plug into the ECM.
Thanks for the replies, I will continue to trouble shoot and let you know what I find out. I sort of doubt that I have water in the fuel since it is the same tank for both engines and all 4 water seperators have been changed, no water in the engine mounted one's and minimal water in the fuel line ones.
As far as the rigging, other than the warning horn not working, everything else has been fine for a year now.
Your motors are acting very similar to what mine did this past weekend. Turned out to be the air compressor. I have also had to replace the TPS on both motors before. Hope you get yours resolved as well.
Just as a question, have you been regularly using any additives like Mercury Quickleen or Sea Foam to help reduce carbon buildup and keep the fuel supply lines and injectors clean? If not I would wonder if the problem might possibly be related to some build up some where in the fuel supply like the fuel rails or in an injector?
If you think it could help, it might be worth a try to decarb with Sea Foam, many others have reported good success. There are ample threads here on THT that describe the decarb process. Best of luck and hope this helps!
__________________
"The problem with socialism is that eventually you run out of other people's money" Margaret Thatcher
31 Fountain Sport Edition
Ok, continuing to trouble shoot.......I swapped TPS, no joy. I swapped coils on the one plug that was badly fouled, no joy.
Yes I have been using Quickleen but I may try a decarbonize procedure too.
I will try to find the fuel filter Demjmm is talking about, I have the repair manual and it isn't jumping out at me but I will keep looking.
If it is the compressor.....should I swap the one from the good motor and see or is this too painful to make it work the trouble.
Sounds like my neighbor will be able to put the test equipment on it tomorrow maybe but if I can figure it out it saves me some money (less than $100) today.
Thanks for all the help, I will continue to report back with the results.
I would agree it may be the compressor based on what I just went through.
On the alarm horn issue those can go bad but are easy to trouble shoot with a test light or multi meter.
When my opti was surging up and down in rpm's, it turned out to be the coil pack and wire. It would get fire intermittently and a surge to wot would ensue. If there is water in the fuel, which is possible but from what you say I would doubt it is water in the fuel, get a portable fuel can for a smaller outboard and run the engine on known good fuel. If your engines are pulling fuel from one main tank, then its not water in the tank becasue you said the other engine is running fine. I'd pay the guy with the ddt to see whats up.... Otherwise you are pissing in the dark.
You can also back the boat into a launch, leave it attached to the trailer and put the engine in gear and rev it up to about 2500.00 rpms with the cowl removed. One by one, remove the injector electrical connector and put it back to see if there is a change in engine performance. If you remove one and notice no change, there is your problem-no spark.... could be a plug, wire, or coil. You can take a coil, wire, and plug from another cylinder and put it on the one with no fire to see if the problem follows. Just switch the parts around to see if the problem moves or stays.
As far as the compressor is concerned, I don't know much about them. I know if they aren't working right your engine wont run or will run like chit. I dont think it s fuel delivery issue because you would have burned the engine up by now without proper lube going in to the cylinders. I know the compressor should be around 80psi and the fuel should be around 90 psi, or vise verse, I cant remember. You can check those two pressure with an automotive style fuel and air gauges that clamp on. You will want to check the psi at different levels of rpms.
I know how you feel as my opti gave me some troubles, but its a complex engine that relies on a lot of electrical signals ans values to run right. My opti has not missed a lick since I got the few small troubles fixed.
I also seen you switched the coil pack around to the plug was was carboned up- remember it could be the plug wire and the coil pack. And if the plug was carboned up it was probably fouled. so even if you put a good coil pack and wire on the cylinder and the plug was fouled-no fire. Also when you switch the coil pakc to another cylinder use everything- the coil, wire and plug Otherwise you are just running yourself in circles pulling your hair out. Once you switch all three components, and see that there is trouble following, then you can trouble shoot each individual part. This is all from experience on my 1999 200hp opti. Good luck my friend.
Just made a trip to the dealer for a few unrelated parts and described the symptoms to him...he very matter of factly said it is most likely a coil or a fuel injector but for $150 he will hook up the computer and tell me what is wrong.
Maybe I should start swapping coils, I figure I can take a coil/wire off the good engine and just plug it in to the "bad" engine and go right down the line, I wouldn't even have to remove the old coil just unplug it.
I still can't find any other fuel filter listed in the diagrams, the system description or by tracing the fuel line on the engine.
Demjjm or anyone else for that matter help figure out where the cleanable filter that Demjjm is talking about?
Similar condition last week except for the idle up to 3000 and then back to 600 like you experienced.
While running at cruise ,one engine would surge up and down. Smartcraft said all temps and pressures ok while running but evidently I was one cyl short. Problem was found to be a bad air injector on one cylinder. Not a pretty fix, with the part around $360 and labor of 2 hrs. And just think with twins I've got a total of 12 air injectors and then fuel injectors as well!!!.
Servicer got me in the next morning after I called and I had the boat back in the afternoon.
Just made a trip to the dealer for a few unrelated parts and described the symptoms to him...he very matter of factly said it is most likely a coil or a fuel injector but for $150 he will hook up the computer and tell me what is wrong.
Maybe I should start swapping coils, I figure I can take a coil/wire off the good engine and just plug it in to the "bad" engine and go right down the line, I wouldn't even have to remove the old coil just unplug it.
I still can't find any other fuel filter listed in the diagrams, the system description or by tracing the fuel line on the engine.
Demjjm or anyone else for that matter help figure out where the cleanable filter that Demjjm is talking about?
Thanks!
Just remember what I said- change everything the coil, wire, and plug. If the plug has been getting wet with fuel and intermittent fire it is fouled. One more thing- you can use a volt meter to do a continuity test on the plug wires.
In today's fuel climate, it could be a number of things. Engines that sit are most prone to fuel related issues, but I hope you are using some good ethanol fighter, like Star Tron, etc.
One odd thing I've had happen a couple of times is burning a small hole in a plug wire boot. Pull the wire off the plugs, and the coil you have suspected of misfiring, (or all of them) and examine them carefully. The hole can be at either end, out the side, and it is trying to go to ground, which could be metal, or twice on mine, it was trying to get through a water hose to the water, which would provide the ground for the current. The hole will be a small black pinhole that could well be your missing, or "surging". Catch it before you light something off.
You are dealing with 40K volts plus, and there have been a number of changes in wire, and boot material to keep the current inside.
Check them carefully, in good light, and you may just find the cause.
Let us know if you find anything.
Tom, thanks for the info and I will let you know if I need a compressor. I think I can rule outa plug wire at this time as I just took a coil and wire off the good engine and one by one connected it to each spark plug then started the engine......same thing every time as far as surging and rough idle. On the first start up it always seem to rev the most, went up to 4k before settling down, each subsequent start it might only rev to 3k then 2k. Not sure if that has anything to do with the surging problem or not, I thought the TPS might have been the issue here but since I swapped them I now doubt it.
Still no joy.
The idle up to 3000 and then back to 600 is probably a fuel or oil leak. This engine is common rail, like a diesel. Anything other than air getting pulled into intake and you are off to the races. (The only reason why you don't loose control of the engine is the ign. rev limiter in the PCM.) The tracker valve diaphragm is good for this. Bad ign. coils are also common.
That one badly fouled plug may be a chipped or broken reed or an oil pump failure. Let me know if the plug does that again.
__________________
...All the wants you waste
All the things you've chased
Then it all crashes down
And you break your crown
And you point your finger
But there's no one around...
J.Hetfield
Timebandit, thanks for the insight. Will the DDT show a fault code for the tracker valve? Is the diaphram something I can change out myself or is it an assembly that I can buy/install? I will look at my diagrams again for this.
You are the first one to come up with a good explaination for the high rev on start up (other than the TPS which I swapped with no joy).
The fun continues!
I think you'll know if its the compressor because you can hear it. Your motor will sound like something is bad wrong with it. (sorry for the pi$$ poor description but my mechanical skills are limited to hammer and screwdriver) Having to replace the belt as well. Fortunately my motors are under factory warranty until 3-27-2012. This ones on Merc!
2001 Optimax 225 surging, TPS bad?
All boats are cool. 
