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bocephus

1990 Jeep Wrangler 2.5L Engine Bucks and Stumbles

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my 90 model whenyou start it it has to wind up bfore it starts then it runs up to abouy 2000 rpms then will settle down to about 1000 but it don't sound like it idles that high. next problem me and momma like to get out and just more or less idle around hardly ever get out of 2nd gear then when you do get ready to speed up it literally will not take the gas itll start jumping and bucking we can switch it off give 30 mins and it cranks and runs fine.problem 3 at highway speeds when you hit a hill and try yo accelerate itll kinda spit like theres water in the gas.ive talked to 2 different dealerships with theyre top mechanic and of course u get two completely different diagnosis. im not bad mouthing theyre techs but  im a faie mechanic myself but this is my first jeep and I honestly do not have a clue.it does have a 195 thermostat ive checked for vac leaks can you check like the tps (ohm it) or how do you do that.ive only got about 4 hair left and they aint got a bright future. seriously whats your take on this thanks Bo

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Hey Bocephus,

 

  Sounds like you have some fuel issues for sure. How many miles are on the vehicle? Have you performed all the standard routine maintenance along the way like plugs, wires and filters?? Sounds like you could have some clogged up fuel filters or even just a dirty carb or aging fuel pump.

 

  If I recall right the 1990 was the last year of carburation. But I believe it still has an electronic fuel pump. Diagnosis over the internet isn't as easy as it seems, but we can get you on the way to eliminating problems. First thing I would do is replace the fuel and air filters (assuming that hasn't already been done). next I would check the fuel pressure at the engine to confirm all is good with the pump. You said you have checked for vacuum leaks already so next would be the choke system. Confirm it is working properly.

 

  After that check your plugs and wires. I know under a load a plug or bad wire can fail to deliver the spark needed to ignite the fuel causing a miss or stutter. If all that is good then I would suggest a carb rebuild.

 

 If you have fuel injection then we would need to look at a few different things like the MAP sensor. Jeeps originally ran a MAP system or speed density system if I recall right. This would mean there was no MAF sensor metering air coming into the engine. Instead they measured a drop in manifold pressure to determine what the engine was doing along with a TPS sensor.

 

  Let me know what setup you have and we will see if we can toss out anymore ideas.

 

Dustin

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thanks guys for the info ths other dicussions  were really helpful. the ool jeep jigger has 168,000 plus on it. stupid me hadn't even thought of changine the fuel filter but ive got ths stuff for a tuneup.let me get that done and ill let yall know if it helped or I know it cant hurt it. excuse my typing but I almost cut my index finger off and in a brace my typing and worth a flip to start with but anyhow  thanks guys Bo US ARMY retired

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