Runs and Sputters After Turning Off
When i shut off the engine it still stutters and runs a bit.
It's an '88 Wrangler 4,2 Ltr. carburated.
I've had this problem with a number of different vehicle (not my
Jeep but it's a 94, so....)
The cheapest things to try are (next time you fill up your gas
tank) add a bottle of Gumout Carberator cleaner in with a new
tank of good quality gas, make sure your air filter is reasonably
clean and (if you haven't done so in the past 20,000 miles)
replace your PCV Valve. Any of these very cheap things could
solve the problem. at worst you've spent under $20 bucks, fixed
most of the easy, obvious things and done no harm in the process.
If it's only sputtering a little, this may well fix it. (The
Gumout was a miracle for one of my cars. I had to do this every
10000 miles, but it was MUCH cheaper then replacing the carb.)
Mine will only do that if I shut it off before it comes off the
fast idle cam (extremely short trips). That's not a good thing
to do anyway (lots of wear and tear, esp. on the exhaust) but
sometimes you gotta move it out of the garage to get the ATV
out... 8^) ! You may be running too high of an idle. That would
do it also. Either case leaves a rich fuel mixture hanging around
when you turn off the key. The engine will try to burn that like
a diesel. Easiest way to ballpark the idle is to read your
sticker under the hood, follow the setup directions, and look at
the tach in the cab. Andy
Keep this in mind: this is caused by additional fuel/air being
sucked in to the engine after spark is turned off, ignited by
compression, or hot combustion chamber.
I'd assume *nothing* is correct, and examine all aspects of the
ingnition/fuel systems. If anything is set to other than factory
settings (ie: tuned by "ear") it's usually hiding another
problem. Check timing ... (does it "ping?") Improper setting
could cause carbon build up in combustion chambers, which can
ignite fuel after the ignition is turned off.
Throttle plate set too wide at idle ... possibly in order to
compensate for something else like a vacuum, timing, or intake
manifold leaks. (See previous posts)
If your engine can get some air through the carburetor after you
shut it off then it would diesel as long as the carburetor can
supply the fuel. Make sure your idle speed is not too high. High
idle will definitely cause this problem. I had the same problem
with my 85 Cherokee (2.8L-V6) and I was hav- ing problems with
high idle and dieseling. I my case it was a worn throttle plate
that would not close down the air passage at idle. Once I
replaced it both problems disappeared.
I don't know if you have anti-dieseling solenoid on your
carburetor. If you do, then it should cut off the fuel as soon as
you turn off the ignition.