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My Jimmy has fluctuating RPMs surging and stalling problems

BEdmondsBEdmonds Member Posts: 1
I have a 1995 GMC Jimmy 4.3 L 4 wheel drive with CMFI injection. Most of the time, the engine runs perfectly smooth. Periodically the tacometer/RPM's will fluctuate. This possibly has something to do with temperature causing it. Recently it stalled and wouldn't start again. Starting fluid was introduced into the intake and it tried to run on the starting fluid. It was clear that there was no fuel to the engine. A fuel pressure check was done and the fuel pressure was holding steady around 55 as it should. During the fuel pressure check, with the gauge attached, the vehicle stalled. The pressure remained constant through the episode. This leads me to believe for some reason, the CMFI injector failed to deliver fuel. What would be the cause for the injector to intermittently cut out? The vehicle doesn't send out a trouble code. Are there any components that control the injector that do not send out a trouble code? Possible crank shaft sensor?? Any suggestions. Thank you so much.


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    mrhendemrhende Member Posts: 1
    I have a 96 GMC 3500 4X4 with a 454 automatic tranny that will start and run perfectly when ran for a while like 30 minutes it will die and not start for about an hour. I have replaced the Fuel pump, the ignition module, crank sensor, and to no avail it still does the same thing. Does any one have any suggestions??
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    mxmom1mxmom1 Member Posts: 1
    What could cause the loss of speedometer after driving for approx 50km or 70 miles? Motor still runs, tach is working between 2500 and 4000 if you accelerate. 300K+ on the odometer (mostly highway travel). If I shift into 1st gear getting the RPMs up then shift into 2nd gear, the speedometer starts to work but I have to get the RPMs to 4K before I can shift into 3rd gear to keep it going. If I let it sit for an hour the problem is gone until I take it for about another 30km or 40 miles then the trani feels like its slipping but if you keep the revs up the problem seems to disappear. Any suggestions to look at would be most appreciated! Thanks!!
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    focofoco Member Posts: 2
    I have a 95 jimmy and the tranny would slip into neutral when giving it gas. I would have to shift it back into drive again. One day when this occured I shifted back into drive and the tranny would not go into any gear. Makes kind of a whining noise now. Any ideas if it could be speed sensor, ignition switch/wiring, front pump, torque converter, or does it sound like it needs a rebuild?
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    lacosselacosse Member Posts: 2
    try changing the fuel filter and run a full bottle of lucas injector cleaner threw it
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    conasnipesconasnipes Member Posts: 4
    You can have a simple possible issue, The 95-97 4.3 had a pressure injector as to an electronic system. meaning the ports on the injectors open with fuel pressure. That being said it can be a Fuel pump issue, the pump being weak would not send any codes. another alternitive option, is to update your injector system, which is surprisingly inexpensive. (i belive its between 200 and 400)
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    olddekaladyolddekalady Member Posts: 1
    edited April 2012
    When going down steep grades I shift from Odrive to 3rd, rpm jumps but car does not slow,on the brakes until the bottom of hill. Occasionally this has happened on level road, car speed creeps up when foot is off the gas, shifting down to lower gears does not slow car down, on the brakes to keep within the speed limit. Have not done any trouble shooting as I do not know where to start. All reg. maint. is up to date, car shifts normally at all times, throttle cable system is not binding, and operates smoothly. This does not happen when the car is cold.Any help would be appreciated. Thank you.
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    hoightoiderhoightoider Member Posts: 1

    Did you ever find a solution to your problem?

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