engine runs terrible...need advice please? Update Fixed!

[marunr]

Well, I did a tune up on my 2.3l omc 1988 (just routine...no engine problems, I've had this boat since it was new and I've always maintained it properly) Took the boat out to the lake for a weeklong vacation and on about day 3 I developed a miss and loss of power. Slowly returned to the ramp with engine coughing all the way. I checked for ignition problems per my seloc manual and determined the points (which I just replaced) were bad. Put in a new set but no change. Replaced plug wires, plugs, set timing at 10 degrees BTDC per owners manual and saw a little improvement but it seemed to run rich. I pulled out the plugs and they appeared to be fouled so I put in a new set. Started up and ran ok for 2 or 3 minutes then seemed to slowly start to miss and flood out, judging from exhaust smoke and smell. I put in a carburetor kit, now it barely starts and I have to really pour the gas to it to keep it running...this causes it to backfire. Tomorrow I'll check the fuel level in the bowl, but I don't think this is going to fix my problem.<br /> So, my questions are these: What else do I look for? Could it be a head gasket, intake manifold gasket, exhaust gasket? <br /> If I take it in, what can I expect to pay just for them to diagnose the problem, before they even start to fix it? Can some of you mechanics tell me what your troubleshooting would consist of and cost?<br /> I'm almost ready to be an ex boat owner! <br /><br /> Oh yeah, I replaced the coil during my initial tune up due to a bad connection on the - post and I replaced one of the 50 amp fuse holders due to corrosion inside the holder. I was having an erratic tach but it smoothed out after these two things were done. Also checked the timing of the cam and it looks good.

 

[Bondo]

Re: engine runs terrible...need advice please? Update Fixed!

It Sounds to Me,<br />That you have some Serious Fuel/ Carb Issues......<br />

I put in a carburetor kit, now it barely starts

You might want to go back Here,+ Start Over............

 

[cobra 3.0]

Re: engine runs terrible...need advice please? Update Fixed!

It may not be getting fuel. Maybe the fuel pump is on the way out?

 

[oldboat1]

Re: engine runs terrible...need advice please? Update Fixed!

If replacing the points was the last thing you did before the problems started (and no prior history of problems), I would start there -- might not be the points themselves, but the way they or the new condenser were installed (and maybe the reinstallation, which you indicate did not solve the problem). It could be a grounding issue, or something similar. Was the distributor cap replaced -- rotor and cap seated properly?

 

[marunr]

Re: engine runs terrible...need advice please? Update Fixed!

Thanks. I'll let you know later today after I check these things out again.

 

[John Carpenter]

Re: engine runs terrible...need advice please? Update Fixed!

If it seems to be running rich and flooding out I would check the overflow line from the fuel pump to the carb and make sure that it is not dumping fuel into the carb.

 

[marunr]

Re: engine runs terrible...need advice please? Update Fixed!

I decided to take out the points I bought at Napa (they got the number from cross referencing my mallory distributor) and put the ones back in that I got a month ago from my marine parts supplier. The rubbing block was just off enough on the ones from Napa to cause me to have to advance the timing too far to make it run.(30 degrees BTDC) Got it started and now I'm back to where I was last weekend. It starts easily but runs rougher the warmer it gets and won't accelerate without missing.(Timing is back to 10 degrees BTDC) I'm convinced it's a carb/fuel problem so I'm going to try a new fuel filter and then talk to a carb rebuild shop to see what they say. My carburetor has fixed jets and I don't know what more I can do with it. Maybe there is something wrong that I can't fix with just a kit...they don't have very many parts in them. <br /> I still haven't checked the fuel pressure but the carb doesn't seem to be starving for fuel. A mechanical fuel pump would not cause an increase in pressure when it fails would it?<br /> Over flow line from fuel pump is dry. Plugs are really getting sooty in a short amount of time. <br /> I haven't checked compression yet but it runs rough inconsistently; I've had bad valves in cars before and they seemed to miss in rythm with the cylinder firing.<br /> Thanks for the help. At least if I have to take it in the shop it will at least start. May save me some money.

 

[cobra 3.0]

Re: engine runs terrible...need advice please? Update Fixed!

Have you tried just timing it by ear while you are running? I found I could really dial in the power this way. (I'll probably get crap from someone on this, but I just couldn't time mine right the conventional way with the timing light.)

 

[marunr]

Re: engine runs terrible...need advice please? Update Fixed!

Yep. Tried by ear. I think it's timed properly but has some other issue. I just found a repair bill on a truck I sold last year which had the same basic symptoms, except it was an EFI engine. It was the intake manifold gasket on that. The dealer dignosed it (with their computer of course) I'm not quite sure how to check that on my boat, but I'll try.<br /> One other note; When starting while cold, it puts out so much smoke that it collects as a black film on the boat stern. Just seems to me to be carburetion, although I guess a leaky intake manifold gasket could cause such difficulty in starting that I might overcompensate with the fuel.<br /> Sorry to be rambling, but I'm starting to obsess on this!!

 

[Wart T]

Re: engine runs terrible...need advice please? Update Fixed!

Did you replace the condenser when you re did the points too? Do it just for laughs.

 

[Blk-n-Blu]

Re: engine runs terrible...need advice please? Update Fixed!

Mar, have you checked the operation of the choke?

 

[marunr]

Re: engine runs terrible...need advice please? Update Fixed!

No. I didn't replace the condenser a second time, but I guess I could try that. The choke operates properly...it's an electric and I can adjust it for a leaner or richer cold start. Adjusting it does change it, but of course it's fully open when the engine is warm and it really runs rough then. Since I've had this boat for 16 years I just know that the exhaust smells too rich. I could even smell it when I was skiing behind it a couple of hours before it started missing so badly. Thanks again! I'll update after I mess with it some more.

 

[DJ]

Re: engine runs terrible...need advice please? Update Fixed!

marunr,<br /><br />Look at the fuel pump. Marine fuel pumps are designed to dump fuel in the carb, not crankcase, should the diaphram fail. That will make an engine run rich.

 

[Bski]

Re: engine runs terrible...need advice please? Update Fixed!

marunr, sounds like carb problems. Sometimes when you rebuild a carb they end up worse than before. <br /><br />What kind of carb is it? Rochester, Holley, or other? <br /><br />I assume that when you mentioned the fuel filter you did check the bronze filter that is located in the carb body where the fuel inlet is located?<br />A lot of people don't know about this filter and they only change the fuel water separator.<br /><br />Also the extra rich mixture could be a float issue so you need to make sure the float is set at the right level.<br /><br />Take your time when taking the carb apart and make sure to clean it real good. I made the mistake recently of taking mine apart and thinking I cleaned it good but must have missed something cause finally the third time I got it straightened out.<br /><br />Good luck, let us know how it works out.

 

[marunr]

Re: engine runs terrible...need advice please? Update Fixed!

I've been reading posts on ignition problems and came across several which indicated I should have 8 or 9 volts at the + side of the coil (to block) with key on. Mine reads 12 volts. I know there is a resistor wire attached, the coil uses an external resistor, but I thought when these went bad the engine wouldn't run. Is it possible for the wire to go bad and allow 12 volts and blow my condenser? Would the boat even run if this happened?

 

[harrydnyc]

Re: engine runs terrible...need advice please? Update Fixed!

I had a similar problem, and it turned out to be the Fuel Filter.. I pulled the inline one out (The one inside the carb), and changed the cannister one, and the boat ran fine for a while.. So, I changed the filter a couple of time, and the problem dissapeared. I guess there was some junk in my gas tank. I know a few other people that have had this same problem..

 

[DJ]

Re: engine runs terrible...need advice please? Update Fixed!

I'm having trouble trying to understand how a fuel filter can cause a rich condition, as described by marunr. Poor ignition COULD cause it, but is not likely.<br /><br />Having 12 volts to the distributor won't cause a poor spark issue either. If anything it will only shorten point and coil life.<br /><br />The problem, in my opinion, is carb or other condition (fuel pump diaphram) causing a rich mixture.

 

[marunr]

Re: engine runs terrible...need advice please? Update Fixed!

Ok. Put on new fuel filter, no change. Friday night I'll pull off the carburetor, take it apart and soak it overnight, then rebuild it saturday and put it back on. I'll let you know how it goes. Thanks for all the input!

 

[Catchem]

Re: engine runs terrible...need advice please? Update Fixed!

Marunr,Reset float and check needle valve has not been scored or scratched.Also check fuel pump diaphram.

 

[Dunaruna]

Re: engine runs terrible...need advice please? Update Fixed!

marunr, with ignition on (not running) you will get 12volts at the coil if the points are open. Should get 8 - 9 with points closed.<br /><br />Aldo