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97 Jeep Grand Cherokee Laredo bogs down/won't gas forward until it is shut off and restarted after 10 minutes


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MattLobo
New User

Nov 20, 2012, 7:48 PM

Post #1 of 4 (3271 views)
97 Jeep Grand Cherokee Laredo bogs down/won't gas forward until it is shut off and restarted after 10 minutes Sign In

I have a 1997 Jeep Grand Cherokee Laredo 4x4 with a 4.0L 6 cylinder motor and auto transmission. It has 98,000 miles on it.

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(sometimes barely), 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 shut it off and 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 fuel pump was getting ready to give out, but the fuel pump was replaced 4 years ago at the Jeep dealer,
and I only have put around 25,000 miles on it. Any fuel 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(but I'm probably wrong). I do sometimes get soft brake pedal pressure off and on.

Any ideas?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 21, 2012, 5:33 AM

Post #2 of 4 (3241 views)
Re: 97 Jeep Grand Cherokee Laredo bogs down/won't gas forward until it is shut off and restarted after 10 minutes Sign In

For now concentrate on the booster, vacuum line to it and a check valve. Careful but you could plug it off tight and see if engine runs properly but you would have seriously compromised brakes to test drive it that way so will default to saying don't but a test while still if part of diagnosing could be done.

Gas issues where you are? IDK and couldn't. If that common and known would make me want to get fuel in gas cans and filter it thru a pump before putting it in vehicle.........

T


MattLobo
New User

Nov 21, 2012, 9:45 AM

Post #3 of 4 (3223 views)
Re: 97 Jeep Grand Cherokee Laredo bogs down/won't gas forward until it is shut off and restarted after 10 minutes Sign In

I just read on Jeep forums that some of the symptoms of the problem I'm having with my Jeep GC Laredo, have been known to be caused by faulty crank position sensors or crankshaft position sensors. Sensor problems seem to be common for Grand Cherokees.

I think it's time for a new brake booster(due to slightly fluctuating brake pedal pressure), but I don't see how it would cause my car to bog out down to idle after driving for a while, and then start working again after being shut off for 5 or 10 minutes. I'm going to ask my mechanic to try your solution for checking the brake booster, just in case.

The gas problem where I'm at(Costa Rica) isn't as much sediment or actual dirt in the gas, as it is from a chemical additive that seems to be in certain batches of gas, which tends to leave residues that build up and mess with fuel filters/pumps/injectors.

Thank you for your prompt reply, and let me know if you have any more ideas on what might be the cause of this problem.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 21, 2012, 1:07 PM

Post #4 of 4 (3207 views)
Re: 97 Jeep Grand Cherokee Laredo bogs down/won't gas forward until it is shut off and restarted after 10 minutes Sign In

The fluctuating brake performance when solved is about certainly vacuum issues. In turn that will cause misinformation for how the engine should behave with assorted symptoms. It should have set a code or one pending by now and not sure if you can get that read so you don't waste more time and $$ guessing IF just taking care of the vacuum leak highly suspected takes care of it.

Fuel + additives: There are countless formulations for assorted reasons. Use of ethanol does suspend dirt and will mean more frequent fuel filter changing. Days of the fuel station filtering it before you buy it are about over. A favorite preventative solvent that seems to really help is called Techron if you can find that I approve its use for prevention of fuel gumming problems. Once a real problem has occurred it would probably take cleaning out the system by machine that may or may not be available near you??

Again - I'd tend to the issue causing the brakes first then if that is found and fixed if problems still exist chase them down,

T






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