Engine starts but wont stay running....

[tcooke]

My 110 Mercruiser will start, but wont stay running. It just bogs down and dies. I have replaced the fuel filter and notta. Where to start.

 

[JustJason]

Re: Engine starts but wont stay running....

start with a compression test.

 

[bamadave]

Re: Engine starts but wont stay running....

How long has it been since a tune-up? Will it idle? Dies when throttle is given? Might be time to rebuild the carb.

 

[chiefalen]

Re: Engine starts but wont stay running....

What year is that motor. Got a manual? How long did it sit before you got it?

Jason as always gave you good sound advise.

Do a full tune up via the manual. Start it on a external tank after cleaning the fuel filters in the carb fitting, fuel pump, and water separator.

If it sat for more than a year a carb. rebuild is in order full of gunk.

 

[JustJason]

Re: Engine starts but wont stay running....

Before you go out and buy this, that, and the other thing for it, do a compression test.
You can go out and buy a 5000 dollar digital fuel injection system for it if ya want..... but if you don't have compression it's not going to run.

 

[bruceb58]

Re: Engine starts but wont stay running....

If it seems like it wants to start while you are in the cranking position of the ignition switch but dies when you release to the run position, it could be that a lead to the coil may be faulty. While you are cranking, there is often a seperate lead that delivers a full 12V from the starter solenoid and in the run position, the coil is fed thru a ballast resistor or a resistor wire. If you have two wires on the positive side of the coil, you have this configuration

I would measure the voltage at the coil with the key in the run position. It will either read 12V if the points are open or something less than 9V with the points closed.

No matter what the reults of this test, I would do a basic tune up including replacing plugs, points, condensor and rotor and also possibly replacing the cap and wires depending on their age.

 

[tcooke]

Re: Engine starts but wont stay running....

OK, after the evening trouble shooting session on the boat I have managed to keep the engine running at higher rpm (1700+ RPM) at idle it will run for a few moments (about 15-20 sec) then sputters and dies. I did this with tweaking the mixture screws and the auto choke adjustment. If you rev it up over 2000 RPM and drop ot to idle it will die immediately. I am not sure of the life of the engine before I got it but the (1965) Merc 110 sat for a few months in my driveway (undercover) while I rebuilt the rest of the boat. I seem to remember the engine used to idle before I stripped the boat before the rebuild.

Maybe just a good shot of carb cleaner at 3000 RPM? I have never rebuilt a carb before, don't know the difficulty level. I believe the carb is a 2GC.

 

[tcooke]

Re: Engine starts but wont stay running....

No matter what the reults of this test, I would do a basic tune up including replacing plugs, points, condensor and rotor and also possibly replacing the cap and wires depending on their age.

Plugs, wires are near new, I haven't taken the cap off to look at the rotor...will do tomorrow.

 

[JustJason]

Re: Engine starts but wont stay running....

http://www.sears.com/shc/s/p_10153_12605_00902171000P

comm'n man... 25 bucks...

 

[Fishermark]

Re: Engine starts but wont stay running....

Plugs, wires are near new, I haven't taken the cap off to look at the rotor...will do tomorrow.

You haven't even looked at the points?

While it sounds like a clogged carb, (and no, carb cleaner at 3000 rpm will not clean it out)... points get pitted over time and glazed from sitting. Put a new set of points and rotor and cap on it and see what happens.