I started the car today only for a few seconds went to shut it off and it tried to stay running for a few seconds. It happen 2 times i did not have time to see if it would do it when the car is warm. I had a problem with a plug wire wiggling loose of the 8 cylinder last week and missing causing the manifold to glow but it didn't run for long like this. I fixed that problem and now this could this be related or something else i only have 300mi on car sence i put the motor in.

 

hmm, what are the specs of the motor? Sounds like you may have too much compression.

 

Maybe, leaky injector...
Compression has nothing to do with it. You have to be getting fuel in the intake runners some how after shut off. Also some pretty hot cylinders (as in lean or wrong heat range plugs) won't help.....

 

hmm, lol maybe not, i had this problem on my old 79 camaro, i thought i remember reading that it was a combination of carbon build up on the pistons, high compression and fuel, idk though... the leaky injector does sound like it may be a thing to check out.... with lower compression the fuel is less likely to ignite so i would think compression IS a factor somewhat

 

Anything that glows in the cylinder chamber can cause fuel to ignite...Compression up to a point is not one...(up to a point is the key term here...eg...diesels, hell my engine might compression wise, if I were to poor gas in the intake). On a injected car there should be no fuel after shutting the engine (ignition) off so, that's why I stated that compression can't be causing the issue. Some how your getting some fuel....there's your starting point....

zx1216
On your older carb car, fuel will pull threw your metering circuit as long as there's a vacuum to pull it. So, a hot cylinder (plug, carbon, compression? what ever) could keep an engine firing and the fuel will flow...They did have carbs that tried to limit the throttle bore openings and when the key was turned off there soleniod would retract closing the butter flies more....it was a crap shoot though because at the time they were trying to run 14.7 to 1 with a carb (pretty hot cylinders due to inaccurate metering) we all know how that turned out.....

 

I guess a leaky enjector could make sence but how would i go about finding out if that is it and which one it is any ideas

 

Usually it will show up as fuel pressure drop over a short time (like a day). If you don't have a pressure gage try this: Pull the whole injector rail up off the manifold (injectors still installed in rail and fuel lines still installed). Turn key to the run position then go out and see if any fuel is leaking past the injectors......If that does't identify the injector/injectors then things are going to get harder quick....Like having the injectors cleaned/flowed checked. Or maybe when you turn your engine off there's still some juice flowing threw your electrical system....Just other idea's.....Your the first injector car I'v have ever heard with this problem...maybe someones already had this problem and can shed more light....if anything you get a free bump....