Problems with Chevy 454 engine

[dolphin2760]

I have a problem with the Chevy 454 engine in a 1988 Dolphin 2760 Class A motor home. After installing new plugs, plug wires, rotor, cap, a loud explosion is heard in the exhaust system upon shutdown, and when the gas pedal is advanced almost fully, the engine suddenly loses power and it sounds like the engine is gasping for air. The engine also will often not shut down when the ignition is turned off, and sounds like it is diseling. The only way I can shut down the engine, and this is really bizarre, is to pull out the headlight switch.

Rodney Stich stich@unfriendlyskies.com

 

[C Nash]

Problems with Chevy 454 engine

Hi rodney,
Several things come to mind that could be your problem. does your engine have the A.I.R system? If so, the diverter valve might be bad. The rear metering rods on the q-jet carb might not be opening. They had a little cam on the top air baffle that raise them under accelerating. High Idle can cause diseling also check for vacuum leak. Don't think the headlights being turned on is anything other than loading the Alternator and creating enough load to cut the engine. Hunt a good Q-jet mechanic. good luck