Originally Posted by Auretrvr
I'm thanking our lucky stars this happened at home and not while we were on the road!
We just got back from a 2,000 mile trip in our '83 310 (Ernestine). I filled her with gas and parked for a couple of days after we got back.
This morning I started it to warm up for a trip to the shop, and she died after about 10 minutes.
I'm a little spooked by this because I just put a bottle of Sta-Bil in the gas tank the other day. But my Onan Generator is running just fine on the same gas as the chassis engine.
The 454 starts, runs maybe 5 minutes and stops. After it sits for a bit I can start it again but it again stalls out. Once it has warmed up, it only runs for a very short time -- 10-15 seconds -- before it quits.
I connected a hose to the fuel line at the carburetor and watched it rapidly pump gas into a bottle. When it stalls I can pump the accelerator and see it shoot gas into the carb but it doesn't affect the stall.
I did check for spark but maybe I waited too long after it stalled, because it had spark when I checked it. I will redo that test.
I followed a mechanic's advice and replaced the manual fuel pump. No change.
Does the electric fuel pump normally run slower once it has built up pressure? Mine never slows down. This could mean a bad pump or leaking tank line, right?
Would a bad coil suddenly start failing when warm? Would it be a very consistent failure, as though it were just shutting off at a certain temperature every time?
Seems like a case of having gas and spark but maybe not enough or not all the time!
It's the Choke.
It's not opening.
GM wires the choke through a oil pressure switch so that the choke only gets power when the engine is actually running. This is to prevent a hard start if you turn the key to run and don't actually start the motor.
When it is cold start the motor with the air cleaner off. Hook a Volt meter to the choke wire and verify that when it starts it gets 12v
once it starts and has oil pressure. If it gets 12v
then the element has failed. If it doesn't get power trace it back to the oil pressure switch and check for power there. No power start looking for blown fuses.
On a 350 the switch is in a oil port right behind the distributor. My 454 is Fuel injected so not sure it where they put the switch. It may be down on the driver side of the block right above the oil pan up near the front of the motor. That's where the fuel pump switch and sender for the gage is.
You should also see the choke open as the motor warms from cold when the choke is plugged in.