OMC 4cyl 3.0L Starts up, won't idle, dies.

[krjohnson76]

Hey there, new boat owner here. After help here w/ a firing order question, I have found and replaced the following problems: New starter, new fuel pump, new points, condenser, cap, and rotor. New thermostat housing (was rusted and nasty). I now have spark, w/ no backfire anymore after getting correct firing order, fuel now getting to carburetor, got rebuild kit for carb and did that, and my engine will fire up for 3 seconds or so, but will die and not idle at all. Need help please. Automatic choke was set to normally open, reversed that to be normally closed, and lined up hash marks. No problems starting up, but then just dies. Suggestions? Help?

 

[PINESOL]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

still could be several things ..
carb rebuild =.... you say it was done .. was it done properly ie. float measurement, did you weigh the float ? was it soaked ? blown out with compressed air.. are the mixture screws 1 1/2 turned out from tight to start with .
dwell angle=
timing= where is it set at ?
fuel=is it good fuel .. ?
when you say it starts up for 3 seconds then dies .. does it high rev then die or does it barely idle then die .. and what year is this thing ..

 

[krjohnson76]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

I did the rebuild, found stuck BB's, corrossion, etc. Cleaned the whole thing out, now I have streams coming to the venturi (sp?) which was blocked before. Did the float measurement according to OEM Service manual, float is plastic, wasn't soaked?? Blew it out with compressed air.. adjusted mixture screws 1 1/2 turns. Will have to read what dwell angle is. Friend of mine who had similar boat did timing for me (he knows a lot, but I am a newbie, and he is out of town now, can ask him about timing setting), new fuel (think I have water in tank, sat for a long time, and before I hooked it up to carberator, was testing it w/ the gas line off at carberator, and water was there, so going to drain and put good in)so I have disconnected from tank, and using gas can w/ hose stuck in it. Revs high, yes, then dies immediately. Can't keep it going by even giving it more gas/less gas, etc. This is a 1987 Bayliner Capri Open Bow. Any help is appreciated.

 

[Maclin]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Sounds a little like a big vacuum leak. Does it make a distinct whistling noise as it revs up?

 

[PINESOL]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

when you did the carb ,,, did you use a new base gasket to manifold ? if so
do yourself a quick favor just to rule out even a defective new pump ...
pull the fuel line off the carb attach a clear piece of hose to the end and into a bucket or another gas can . then try starting it .. you should be able to just watch the fuel pump through the clear tube this insures your not running into a fuel pick up problem .. sounds like you are burning the gas thats in the carb then it dies ... have you tried keeping it running with a little bit of throttle ? you dont want to run that thing at high rpms while on muffs though. your problem sounds like a carb . but you need to rule out fuel supply to the carb first.. if your getting plenty of fuel ... redo the carb rebuild and double check everything..

 

[krjohnson76]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Yup, I pulled off the fuel supply line, and I am getting gas (spurt...spurt...spurt). Tried giving it throttle, no success. Still dies. So confused, thought I was getting so close. I will pull off and try again.....any other advice? Will post after I do it today.....

 

[Fishermark]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Forgive me if this sounds basic - but the gas line you put into the gas can - it goes to the fuel pump, not the carb, right? Just checking.

Also, some carbs are so old and corroded that they simply cannot be rebuilt - even by professionals with all the proper equipment. That sounds like your problem.

 

[Don S]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Try this test.
Make a jumper wire and clip it onto the + terminal of the coil, hook the other end to the + terminal of the battery. Start it and see if it keeps running.
If it does, disconnect the wire and see if the engine stops.

 

[Maclin]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Coil ballast circuit check, good idea, matches symptoms

 

[krjohnson76]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

I made the jumper wire, connected to coil + and battery +, and BOOM, it started to idle!!!!!!!!! WOOHOO! I am a newbie here, and to boats, and I like to learn from mistakes/problems......so what was wrong? And where do I go from here? Replace the ignition coil???

Thank you all, for all your current/future help. I will get whatever I need tomorrow, depending on what you guys say I need. This is awesome!

 

[Don S]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Nothing wrong with the coil, you were using it. What I need to know is what year is this OMC 3.0L Ignitions systems have changed on the same engine over the years.

PS, it is a minor problem.

 

[krjohnson76]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

It is a 1987 OMC Cobra 4.0Cyl. 3.0L Does that help?

 

[Don S]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Yes, that helped. Be back shortly with a diagram and what to look for.

 

[krjohnson76]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

I have the OEM Service manual if that helps at all...and Don, Thank you. Thank you very much. I see you on this site answering everyones questions. I don't know how you find time to do it. Not kissing a**, just very appreciative.

 

[Don S]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Below is a link to the wiring diagram for your engine.
Somewhere from your ignition switch to the + terminal on your coil, there is a break in your Purple ignition wire. Your mission, should you choose to accespt it is to find where the power stops. Could be the ignition switch, or any connection from there to the engine. Could also be the alternator, or splce for the purple/red wire on the connection from the alternator.

Engine Wiring Diagram

Inst harness wiring diagram

 

[krjohnson76]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

I suspect I know where it is. Tomorrow, I will check it. My 3 boys (single father) are in need of attention. I will let you know tomorrow what I find. Thank you again, Don, for your help. It is much appreciated. Will post results as soon as I try your suggestion.

 

[Maclin]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Bullseye Don!

 

[wallydc2]

Re: OMC 4cyl 3.0L Starts up, won't idle, dies.

Well!! were was it? Some us would like to know just in case someone else has the same problem.