Mercrusier 3.0 won't stay running

[captain klemm]

Have a 1988 Maxum with 3.0 Mercrusier . Boat had no spark, changed out cap , rotor, condensor, plugs and points. Boat fired right up but will not stay running.
Engine will stay running if you continually pump the throttle cable. Changed out the filters at the pump and carborator . the carb filter had some jel in it. Tried to start it again and still the same problem. Checked the plugs , all were black carbon with fuel residue. I'm thinking it may be the coil. any thoughts?

Thanks

 

[Maclin]

Re: Mercrusier 3.0 won't stay running

1.) "Engine will stay running if you continually pump the throttle cable."

2.) "... the carb filter had some jel in it...."


#1 indicates you have spark, so why would you want to change the coil.
#2 says that your carb main and idle jets are probably gunked up and you need a carb rebuild.

When you pump the throttle the accelerator pump in the carb grabs fuel from the carb fuel bowl and squirts fuel into the throttle body through nozzles under pressure and that is enough to keep it from dying. The reason it cannot keep running if you stop the throttle action is the carb cannot supply fuel thru the idle or main jetting passages.

 

[Maclin]

Re: Mercrusier 3.0 won't stay running

The accelerator pumped fuel is raw and not atomized and can show up on the plugs as a rich condition and wet the plugs as well.

 

[captain klemm]

Re: Mercrusier 3.0 won't stay running

Thanks for your quick reply, The carb rebuild it is. My only thought on the coil replacement was that the plugs had so much excess fuel on them I thought that it may have not have been getting enough spark thanks again for the quick diagnosis