motor stalling in gear when warm??

[rbh]

1985 260 mercruiser engine starts fine cold, idles good in gear (when cold), but after awhile on the lake cruising, bringing the engine down to an slow idle in gear causes it to die.

what should I be looking for vacuum leak between the carb and manifold, sticking choke?????

Thanks

Rob

 

[Stamey]

Re: motor stalling in gear when warm??

Well, when it is cold, the choke is probably still closed part of the way, and when it opens your idle problem exposes itself. This could be a range of things, like gunk in the idle circuit of the carb, a vacuum leak, or may be electrical.

You probably do not have a stuck choke, but that's easy enough to check. Just have a look at it once the engine is warm and see if it is open. If you don't know, this is the flap/plate at the top of the carb inlet.

Have you checked your fuel filters? It likely has a fuel filter/water separator and a fuel screen in the carb fuel inlet.

To check for a vacuum leak you'll want to spray carb cleaner around the carb, everywhere but the carb intake, in small bursts, to help narrow down the location. This should be done when the engine is warm. If the engine revs up a little the carb is getting fuel through a vacuum leak where you just sprayed.

If you have a 4-barrel, a quadrajet, is it possible to have a vacuum leak internal to the carb. I have read about this but have not experienced it and do not know how to troubleshoot it.

Chris

 

[Volphin]

Re: motor stalling in gear when warm??

First things first. Look for a vacuum leak as described above. Barring any leaks, double check your timing and idle speed when warm. You may also want to check the idle mixture on the carb after that. Pulling a plug or two to eyeball their condition wouldn't be a bad idea either.

V

 

[rbh]

Re: motor stalling in gear when warm??

Timings good,
Waited till the choke and thermostat opened, sprayed wd-40 around base gasket and ventury gasket??
(RPM's did not pick up)
3.5 turn out on the air fuel mixture screw, no changes +- 1.5 turns.
plugs and wires new (nice lite brown around electrode)

Just alittle confused what comes next?

 

[Bondo]

Re: motor stalling in gear when warm??

Ayuh,... It's entirely possible the carb's idle circuit is restricted or plugged, 'n the choke is hidin' it when cold...

Open up the carb, 'n rebuild it...