Mechanics

JEEP GRAND CHEROKEE GAS PROBLEM

1997 Jeep Grand Cherokee • 98,000 miles

I have a 1997 Jeep Grand Cherokee Laredo 4.0L.

I'm having a problem with it suddenly not wanting to go forward while driving it, after 20-30 minutes or around 4-7 miles of driving. It stays running/idling, but when you press the gas, it sputters and starts to die until you let up on the gas pedal. It will only move forward at about 1 or 2 miles per hour(on flat ground), or won't move forward at all.

I can get it to start working normal(it feels like it's running at 95% normal), if I let it sit for 5 thru 10 minutes. Then I start it up again, and it will usually work again(until it heats back up?). While this goes on, the oil pressure is normal, as is the engine/radiator heat level. All cylinders sound like they are firing right, and it doesn't put out any smoke.
My injectors aren't leaking either.
I do hear a hissing sound coming from the brake booster areas for around 30 seconds when the problem starts up again, but it disappears after I stop and restart the engine.

I live in an area around 4000 ft above sea level in a Costa Rica mountain area, and the temperature is always between 60F-78F. This area is where I am experiencing this problem with my Jeep. The nationwide gasoline suppliers do sometimes have batches of dirty gas. Some folks get problems with their fuel systems because of this.

I was told my fuel filter might be dirty, or the gas pump was getting ready to give out, but the gas pump was replaced 4 years ago at the Jeep dealer, and I only have put around 25,000 miles on it. Any fule filter or fuel pump will have to be ordered from the US.
I'm thinking it might be something electrical or a problem with the brake booster. I do sometimes get soft brake pressure off and on.
Any ideas? If you can correctly diagnose my problem, I will donate $10.
Thanks in advance.
Matt
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November 21, 2012.



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