3.0 hard starting when cold

Rderr12 · Jul 17, 2013

I have a 1989 bayliner with a 3.0 omc cobra GM motor.. It's have a rough time starting when cold.. But once it starts it starts up every time like a champ.. I've tried the pump it a couple times.. I have a pull out throttle.. The guy I bought the boat from said he replaced plugs wires and the coil.. I have a brand new battery.. I checked the spark plugs they are getting spark.. Only thing I can think of is maybe the starter is starting to fail? Need help!

RogersJetboat454 · Jul 17, 2013

Re: 3.0 hard starting when cold

Welcome to Iboats.

If the starter spins the engine over at sufficient speed, no need to blame it, it's just doing it's job.

On most carbureted boats, you're supposed to pump it to full throttle a couple times before a cold start, and set the throttle lever to just off idle. Is this what you are doing?

When you pump the throttle (you're going to need a buddy/wife/GF/smart dog for this) can you see fuel squirting down the throat of the carb? If not, the accelerator pump may be shot.

Finally, when you pump the throttle, does the choke plate on the top of the carb close? If so, how far?

Rderr12 · Jul 17, 2013

Re: 3.0 hard starting when cold

Yea i can see a nice amount of fuel going into the carb.. I can smell it as well.. I took the flame off and the butterfly opens and closes as the engine turns and yes I give it about 4 or 5 pumps leave it a little above idle.. It takes my buddy to flap the butterfly to start. And then it will start every time afterwards but let it be for a day and were doing it all over again... Thanks for greeting

RogersJetboat454 · Jul 17, 2013

Re: 3.0 hard starting when cold

Rderr12 said:
It takes my buddy to flap the butterfly to start.

The choke plate is what you're talking about right? And your buddy is holding it closed?
If so, it sounds like it may be out of adjustment, or need repair.

Rderr12 · Jul 17, 2013

Re: 3.0 hard starting when cold

Yea the choke plate.. And no he flaps it.. It's a spring loaded choke plate.. It's on the side of the carb I'm wondering if it needs to be tightened or loosened? I just had the carb rebuilt about a week ago because of this.. It's a Rochester 2 barrel carb.. Is it supposed to be closed when starting?

alorio1 · Jul 17, 2013

Re: 3.0 hard starting when cold

Youre automatic choke seems to be out of adjustment. There are three screws on the choke plate holding the plate stationary. Loosen these screws and rotate the plate clockwise until the choke butterfly closes lightly shut. This can be only adjusted to a cold engine. When the key switch is turned on , voltage heats the spring which is made of heat/cold sensitive metal. So, when the engine switch is turned on the spring starts to heat up and choke butter fly will begin to open. If you are spending time with the key switch on listning to the radio while loading the boat or for what ever reason the choke butter fly will be heated up and moved from closed position to open because it thinks the engine is running and choke is no longer needed.

Silvertip · Jul 18, 2013

Re: 3.0 hard starting when cold

What do you mean when you say your buddy is "flapping" the butterfly? On a cold start the choke plate should be closed -- period. It can't choke if someone is "flapping" it open and closed (if that's what you mean). And DO NOT try and adjust the choke on a warm engine. It needs to be done a stone cold engine that has had the key in the off position for several hours (preferably overnight).

Rderr12 · Jul 18, 2013

Re: 3.0 hard starting when cold

I adjusted the spring after letting it sit over night the spring was very loose barely holding the choke plate closed.. Every time I go to start the engine the choke plate moves up and down is the supposed to happen? And how does voltage heat the spring if there is no voltage going to the carburetor? And how tight does the spring need to be?

alorio1 · Jul 18, 2013

Re: 3.0 hard starting when cold

The spring choke butterfly should be lightly closed by the spring if thats what you want to call it. There should be a single wire running to the choke plat with voltage when the ignition switch is on. Someone must have left it off if you don't see one, therefore your automatic choke is never going to work right until you resolve this problem.

Rderr12 · Jul 18, 2013

Re: 3.0 hard starting when cold

Ok i don't have the carb your talking about it's a 1989 Rochester 2 barrel carb for a 3.0 omc gm motor..

Rderr12 · Jul 19, 2013

Re: 3.0 hard starting when cold

Ok update.. My carburetor has a circle black piece held on by three screws there is a swirled spring attached.. That is the spring for the choke plate.. I have adjusted it to where it is loose.. And adjusted it to where it's tight and both times when the engine is cold and either way the motor just cranks and cranks.. I had my shift cable replaced and ever since I've had this problem.. Frankly I'm quite frustrated with it.. The boat started fine but shift cable was broke.. Now shift cable fixed and it doesn't want to start.. Getting very annoyed.. Haven't had the boat on the water since May.. Just want to be on the water already..

bruceb58 · Jul 19, 2013

Re: 3.0 hard starting when cold

As a test to see if the ESA is causing your problem, unplug it and try.

Rderr12 · Jul 19, 2013

Re: 3.0 hard starting when cold

Ok.. If I disconnect that will the motor stall trying to go into gear?

bruceb58 · Jul 19, 2013

Re: 3.0 hard starting when cold

Its used getting out of gear. You need to have it connected normally but you can disconnect it for this test to see if its the cause of your problem.

Rderr12 · Jul 19, 2013

Re: 3.0 hard starting when cold

Ok will do.. I'm going to test it right now

Rderr12 · Jul 21, 2013

Re: 3.0 hard starting when cold

The esa switch didn't work.. Anybody have any other thoughts?

Boomyal · Jul 21, 2013

Re: 3.0 hard starting when cold

A) Does the choke plate stay closed when you are trying to start it? B) Have you pulled the plugs to see what they look like?

Rderr12 · Jul 21, 2013

Re: 3.0 hard starting when cold

Yea it does and plugs are brand new and all are producing spark

Boomyal · Jul 21, 2013

Re: 3.0 hard starting when cold

Rderr12 said:
Yea it does and plugs are brand new and all are producing spark

Still would be good to have a look at them. You need spark, at the right time, air and fuel. Plugs often have a story to tell even if they have only been in a short while.

bruceb58 · Jul 21, 2013

Re: 3.0 hard starting when cold

Rderr12 said:
The esa switch didn't work.. Anybody have any other thoughts?

I am assuming you meant unplugging the ESA module didn't work.

3.0 hard starting when cold

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