Mercruiser 3.0 stalls at low speed

[hillsideman]

Last season (2010) I purchased the boat of my wife?s dreams, a 2002 Bayliner 185 with a Mercruiser 3.0 litre 4 cylinder in-line engine. Since that time I have been struggling with 2 problems. 1.) The engine will not idle until warm. I have to pump the throttle to keep the engine from stalling until it warms up. 2.) The engine often stalls when throttle is applied from a low forward speed or from neutral. This makes for interesting situations when exiting my slip at the marina in breezy conditions. With mid to full throttle the engine runs fine.
So far, I have tried gas additive (Seafoam), carb cleaner (Deep Creep), a new fuel filter, and new plugs. A local marine mechanic, who was recommended, said he found no problems when he put the boat in his tank. I can?t give you rpm info because the tach is unserviceable on this little gem.
I could learn to love this boat if it didn?t give me ulcers during low speed maneuvering. I have browsed the forum and haven't found a problem close enough to mine. There is so much information out there, I don't know where to start. Any suggestions would be appreciated !!!!

 

[Bt Doctur]

Re: Mercruiser 3.0 stalls at low speed

Carb may need a rebuild, accel pump may not be working properly, mixture screwsd may be set too lean.

 

[fishrdan]

Re: Mercruiser 3.0 stalls at low speed

^^^ that's what I was thinking as I read though...

On the engine being cold blooded, are you setting the throttle to a high idle (1200-1500RPM) and letting the engine warm up, or just starting a cold engine and dropping it back to low idle? It's a carbed engine, so it's not going to cold start like a modern EFI engine.

 

[hillsideman]

Re: Mercruiser 3.0 stalls at low speed

To start the engine I have to give the throttle a few pumps and then set it to a high idle. To keep the engine from stalling, I have to keep adjusting the throttle until the engine warms and will maintain the idle.

 

[cr2k]

Re: Mercruiser 3.0 stalls at low speed

What BT Doctor said, your carb needs a new accelerator pump. With engine off pull the flame arrester have someone pump the throttle. Do you see a good squirt of gas down the opening? If yes your idle circuits are plugged, if NO your accelerator pump and or circuits are bad.

 

[hillsideman]

Re: Mercruiser 3.0 stalls at low speed

Thanks. Useful info. I'll check all of the above this weekend.

 

[Aatcman]

Re: Mercruiser 3.0 stalls at low speed

2nd what cr2k said.

Also, your choke could be set waaay to rich (Or it could just simply be stuck) -- it opens and leans out somewhat as the engine warms up.

Needing to pump the throttle a couple times to start a cold, carbureted engine is normal -- but it should be willing to drop to an idle shortly thereafter....

Easy to check -- get the engine warmed up (and run it for a few minutes after its warmed up) then pull the flame arrestor and see if the choke is all the way open

 

[hillsideman]

Re: Mercruiser 3.0 stalls at low speed

I think that my cold start problem is a stuck choke. I removed the flame arrester and did a cold start, keeping my eye on the choke. It never moved from wide open. This seemed wrong to me. It's an electric choke. Is this a DIY job???