1998 GMC Jimmy check engine light

Ask our auto mechanics for help to all your GMC truck questions.
GlennVnaz

1998 GMC Jimmy check engine light

Unread post by GlennVnaz » Mon Dec 28, 2009 10:43 pm

Engine begins to misfire and stutter and the temperature gauge drops to zero and then bounces around. After a while the service engine light goes on and misfire worsens. 1998 GMC Jimmy 4x4, 4.3L, 113000 miles

After driving the vehicle on highway for aprox. 2 hours. Problem goes away after vehicle rests for a while.
Problem does not occur in stop and go traffic or when traveling on winding road with intermittent acceleration.
Problem only occurs when acceleration is constant for about 2 hours.

One mechanic said it was the fuel pump. New fuel pump & filter was installed, $750 later and the problem still exists.

I pulled a plug and it is very black and burnt. It appears to be running too rich.

Stan

Re: 1998 GMC Jimmy check engine light

Unread post by Stan » Tue Dec 29, 2009 3:15 am

Well, the check engine light means there is a code stored iin the computer.
You would need to get that scanned to see what the code is.
If more tahn one plug is looking black from running rich, i would suspect a fuel ressure regulator.
If only 1 plug, sounds like stuck injector.
Non of this explains the coolant temp though. That may be just low coolant or sticking thermostat.
Unless the intake or head gasket is leaking coolant and causing a cylinder or two to fowl out.

scotty
Posts: 19
Joined: Sun Oct 14, 2012 11:52 am

Re: 1998 GMC Jimmy check engine light

Unread post by scotty » Thu Feb 21, 2013 9:39 am

Do a pressure check on the cooling system. With the temp gauge going up and down, that means there is air in the system, especially if the heater temperature goes warm and cold.

Air pockets in the cooling system along with the engine misfire means a possible leaking head gasket. Coolant would get into the cylinder and foul out the sspark plug. Remove the plugs and inspect for corrosion.

  • Similar Topics
    Replies
    Views
    Last post