Cold engine stalls out when idling

[girraf]

Except for this minor problem, the engine runs flawlessly. I've got a VP 5.7L GL, carburated. During cold starts, the engine will turn over just fine, kick up to 1200 or so before settling around 800 rpm. After about 45 seconds to 1 minute, the idle speed slowly drops over a few seconds and the engine stalls out. Bump the key and she fires right back up. My workaround is to apply some throttle to keep the rpms up and that prevents this from happening. I'm guessing that an adjustment of the carburetor is all I probably need, but not sure which screws to turn. Any suggestions? By the way, this happens both on the hose and in the water.

On a previous post i made about the same problem, some folks mentioned a thermostat problem. I just had the boat out yesterday in the Chesapeake bay area and the engine never got up above 130 even after some cruising. I know the water is only about 50 degrees, but from what I hear around the forums that is running temp is close to 160-180. Could I have a stuck thermostat that's always (open I guess?) and not recycling the block water until its up to temp?

 

[Maclin]

Probably a simple choke adjustment. When the engine is dead cold, take the flame arrestor off and see if the choke plate is closed. It is a thin hinged plate on the front 2 barrels at the top. When cold it will cover the top of the front barrels. It should move some when you push on it, and then move back to closed as it is linked to a spring loaded bi-metal coil. If it is not closed then it needs to be adjusted or troubleshot to see why. If it is closed, it may be opening too soon (or not closed all the way). The rate of the gradual opening is a constant as the choke is electric, mechanism is the bi-metal coil. If it needs to be adjusted, this is accomplished by moving the black choke housing on the side of the carb towards the "R" setting after loosening the 3 small keepers.. Does not need to move much. This will keep the choke closed a little longer.

 

[Scott Danforth]

Sounds like both a sticking T-stat and a choke adjustment

 

[dennis461]

If engine is warm will it idle for 5 minutes without stalling?

 

[girraf]

If engine is warm will it idle for 5 minutes without stalling?

I can't be certain of the idling characteristics of my warmish (130-140 deg) engine. I suspect it will hold idle longer when its warm than when its cold.

Something else that just came to mind is that my oil pressure is pretty high, usually around 40 (psig) I think around idle and upwards of 70-80psi running with a decent amount of power. This would correlate with low engine temp and high oil viscocity. Probably should check the T-stat.