Schutte

Sometimes my 98 cherekee wont shut off when I turn the key off. It spits and sputters and then dies out slowly. Then sometimes it turns off fine. What could this be?

ZJMAX

Timing too advanced & carbon build up in combustion chambers are a couple.

Max

Schutte

Thanks I'll check those things.

freegdr

Ignition switch ?

ZJMAX

He says spits and sputters, if it were the ignition switch i would think it would just keep running. Sounds more like the engine is dieseling.

Max

Bluelight

A leaking fuel injector is also likely part of it.

Schutte

How can I tell if it's a fuel injector?

freegdr

[QUOTE=ZJMAX;3128143]He says spits and sputters, if it were the ignition switch i would think it would just keep running. Sounds more like the engine is dieseling.

Max[/QUOTE
Anythings possible

Bluelight

For an engine to diesel, you need to have a supply of fuel and an ignition source. Carbon build-up inside the cylinder is a common ignition source, and these engines are somewhat known for carbon build-up. The fuel source would most likely be a leaking fuel injector. Dieseling was common in the days of carburetors, because as long as the engine kept turning, the carb kept feeding it fuel. With FI, the injectors shut off when the ignition shuts off, making dieseling rare these days.

First check would be a leakdown test. Hook a pressure gauge to the fuel rail test port than cycle the ignition switch on than off a few times to build pressure in the system, than monitor the pressure. It should not drop below 30 PSI within 5 minutes. If it drops faster than that, you have a leak somewhere.

To see which injector is leaking, remove the fuel rail/injectors from the manifold. Cycle the ignition switch to pressurize the system, than check the injector tips for dribbling fuel.

freegdr

So if ignition switch is malted or defective in some way and could be not ctting current off right away it could still be feeding power for dieseling to occur.

Bluelight

I wouldn't think so. There aren't separate contacts in the ignition switch for the injectors and spark. They is only one contact that powers them all. If the switch weren't opening, the thing would just keep running. For the injectors to fire, it would mean that the computer and all the associated sensors would have to be running too.

freegdr

Its possible it not making full contact mabey alowing less than 12 volts threw kinda like a low batterywould turm motor over slowly but not fast enough to start it. If coil wire is removed wonder if it would shut down immediately ? Electrial can do strange things as we all know to well.

freegdr

Maybe....


Update: The ASD relay was the problem. The fan relay is seperate!! Evidently, the contactors continued to contact or arc enough to keep the circuit closed for a couple of seconds.

Thanks for everyones help and I hope that my solution helps someone in the future.

freegdr

Switch with similar relay..

Bluelight

I had the same thing happen to my efan relay. For a week until I could get a new one, after shutting the engine off, I'd have to pop the hood and thump the relay box to get the relay to open and the fan to shut off.