1999 Jimmy Intermitent Hesitation .. Plz Help.

08-15-2004, 01:04 AM
I have a 1999 GMC SLS Jimmy 4.3L Vortec.

~ 1-2 hours into a highway drive, the Jimmy seemed to have a loss of power. I thought it might be wind, it was not. I then filled up with gas and the problem persisted and the check engine light came on. I later topped up with some other gas and the light went off (note, on a later drive, the same scenario occured, bad gas from one station???). I would stop and shut the engine off and everything appeared to be okay after.

This continued until last week I had a dead cell in my battery and the alternator died. Replaced both and things but I noticed more hestitation when driving in the city. I noted that if I take my foot off the gas during it's hesitation and press down again, it worked fine.

All was well until I was on the highway again. ~ 2 hours into the drive, loss of power. I could only go 60 mph, if I hit the gas, the revs would go to 4-5,000 and I could only get to 70 mph. I pulled over, shut the engine off and checked fluids, all fine. I started er' back up and hit the highway and all was well again.

Please forward any suggestions.

Note: in the past 3 weeks I had a new battery, new alternator, new plugs, new fuel and oil filter (tuneup) and have been running some fuel system cleaner (intermittently).

Any help greatfully appreciated. NOTE: the only other minor problem is the signal arm is shorting out causing the clicking sound when no signals on.

LESTER :eek7:

08-15-2004, 01:06 AM
I should have mentioned that:
1. I lost my gas cap and replaced with an aftermarket. Shortly after the probs with the check engine light started but have not returned.

2. I replaced the air filter as well.

08-23-2004, 09:54 AM

08-23-2004, 11:56 AM
Hey Lester;

I was told awhile ago by a dealership mechanic that any time your service engine soon light comes on, its something to do with your emissions control system. (I dont know if you are Canadian or American, but emissions control is a big thing in Ontario...) It could be anything from an O2 sensor, to your catalytic converter, or even your gas cap if it isn't threaded on properly. Generally, the first thing to check is the gas cap. If it isn't on tight, or if its crooked, it'll set your light going. If the Service light starts flashing, get it to a shop quick, or you'll be paying a big bill.

I know I wasn't much help, but...

09-16-2004, 02:17 PM
Lester -

It sounds like you have a sluggish transmission. I have a 2000 GMC Jimmy, and have been having the same problem (identical) with mine. I have had $800 worth of work on this thing in the last three months. It came to a head in June when my ABS light came on, my speedometer stopped working, and I didn't shift out of first gear. I have an automatic, just so you know. It became apparant that the VSS (speed sensor) was faulty, it was replaced, and everything was going well again, with a remaining slight hesitation during acceleration. That problem has gone back to its normal self over the last month or two, and my service engine soon light came on yesterday night. I think that the transmission fluid may be low, or there is some other problem with the transmission to keep it from shifting smoothly from one gear to the next. I am getting mine taken to Cottman tomorrow to get a free 21-point diagnostic test. I'll know tomorrow what the problem is and how to fix it, so I'll have to drop by automotive forums and let you know the out come. I don't think this was very helpful, but I thought I would let you know that some manner of help is on the way. ;)

09-16-2004, 11:09 PM
Please let me know. Any information is greatfully appreciated!

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