Help - 85 Chevy 454 won't stay running
 

To all of you Chevy big block gurus out there: I have an '85 RV with a Chevy 454 engine. It won't stay running. It idles for maybe 10 mins then dies and won't start again UNLESS I turn the key to Off then back to On and then Start. Then we're back to idling for 10 mins then dying.

This is what I have changed: I first thought I had a fuel issue so changed the mechanical fuel pump, It also has an electric fuel pump back at the tank that was added. After discussing with someone I thought there might be a carburetor issue so I replaced with a rebuilt Quadrajet. Inside the distributor I have replaced the coil, cap, rotor, and the little module you thermal-paste to the floor of the distributor. Also replaced the plugs and wires.

I plumbed a pressure gauge into the fuel line at the carb - running around 5 psi.

Watched the pink power line (IGN SW) at the distributor - never goes away.

I haven't changed the pickup coil after talking to a Chevy guy. (Said it had a different failure mode.) I also see on the diagram in my manual an "ESC Controller." Has anyone heard of that causing this issue?

It acts like something times out and then causes the ignition to shut down. Why would it not start again until AFTER I turn the key to Off.

Running out of ideas and we would really like to start using this RV. I can't even drive it to a shop. In gear, only runs for about 2-3 mins before dying and the storage lot is about 20 miles from a shop that would look at it.

Anybody?

Sounds like a fuel issue. You didn't mention if you checked key on power at the electric fuel pump. If not, turn the ignition key to the ON position and check for power or listen to see if the pump is working.
You mentioned that you have have 5 psi fuel pressure, is that with the engine on and idling until it dies? It may be that the electric fuel pump is wired to the Start wire rather than one that is 12v with the ignition on. In this case, the pump would run while the key was in Start, filling the carburetor, then turn off when the key is released and goes back to the on position.
What happens to the fuel pressure just before and just after the engine dies? Did you change or check the fuel filter or filters? Keeping the engine running is a function of fuel flow as well as pressure.

You should have put a Holley carburetor on your Chevy. The Quarajet carb is likely causing your issues. It takes an expert like me to work on a Q'-jet. It has to be one of the worst 4-BBL carburetors ever designed. An Edlebrock is also a good carb, but Holley always was much better than a Q'-jet. Don't let those small primaries fool you. It's a gas-hog carb through and through. Also, your fuel pressure is low at 5 PSI. Your fuel bowl is likely running out of gas, since 9 PSI is the minimum and on some up to 16 psi. You'll have to reset your fuel bowl levels and buy a new fuel pump. Better to buy a Holley, IMO. Lots of Chevrolets came with Holley Carburetors. Once they are set, you likely will never have to worry about it anymore.