1999 GMC Jimmy missing

DAN WEEGE

MEMBER
1999 GMC JIMMY
6 CYL
4WD
AUTOMATIC
147,000 MILES

I have a 1999 gmc jimmy I have replaced the fuel injectors, fuel pressure regulator, fuel pump, distributer cap, rotor, and coil. When we drive it it runs great up to about 55, 60 mph then it starts jerking every now and then any ideas thanks

Thursday, October 21st, 2010 AT 7:15 AM

3 Replies

WRENCHTECH

MECHANIC
20,758 POSTS

The first thing I would do is rig up a fuel pressure gauge in a way that you can run the hose out the back of the hood and tape the gauge to the windshield so you can drive it and watch the fuel pressure. This engine is very pressure sensitive and must maintain over 55 PSI at all times.

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Thursday, October 21st, 2010 AT 7:18 AM

ZOUM63

MEMBER
2 POSTS

I have a 2001 Jimmy with similar problem.
I also have over the last few months made some repairs like: new fuel pump, rotor cap & coil before it started to do this engine miss. I have noticed that when mine acts up always at/or around 55/60mph. Either way with cruse control on or using foot pedal the tach. Jumps up and down eratickly but the rpm's of engine is not going up and down. Engine runs fine at higher speeds or lower speeds.
Could that possibly be a flat spot in TPS?

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Monday, October 25th, 2010 AT 10:28 PM

WRENCHTECH