Fuel cutoff at highway speeds ?

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mberthia

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Not sure exactly what the engine was doing but it felt like the fuel was cutoff for an instant like when reaching redline.
I was in 5th gear (MT) at about 75-80MPH guessing about 3000RPM. I would let go the gas pedal and try to get back to speed and it would do it again. I slowed down for a while before going back to the same speed an it did not do it again.

Any ideas what was causing it ?
PCV valve and plugs were changed 5k miles ago.
 

LibertyTC

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Did the check engine light come on? An engine requires 3 things to work well, Fuel, air and Spark, which one that is not working well is a process of elimination in many conditions, without a check engine light.
What year Kj, and how many miles on it?
When the spark plugs were installed did you check & set the gaps correctly?
As a vehicle accumulates mileage, keeping the jeep in good tune requires attention to many areas including: A clean throttle body and air filter, fuel injectors, and good flow from the fuel filter, a good battery that passes a load test, and clean oils/fluids.
Without knowing the mileage on your vehicle, I would start with something easy like fuel delivery, and obtain a bottle of Chevron Techron added to a half a tank of mid grade, and take the jeep for a good highway boogie at 60-70mph for that half a tank and see if that helps, and if you are a higher mileage KJ then replace the fuel filter if problem persists. Cleaning the throttle body manually is fairly easy,obtain a spay can of throttle body cleaner, remove the clamp & air intake hose and follow directions on can. I would normally remove the Idle air control motor and Throttle positions sensor and include ports as process of cleaning the throttle body as well. Lots of carbon can accumulate in these ports and units. If you are not into doing the work yourself, the dealer can offer an emission service/throttle body clean, as well as change the fuel filter etc...Hope this helps.
 
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mberthia

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No check engine light - yet.
2003 with 72k miles.
I did the plugs myself and I had checked the gap.
Before, I do anything I will have to see if it does it again. It was starting to rain so moisture may have had an impact.
 

tjkj2002

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Couple of main causes for your issue................

1-restricted exhaust,IE plugged cats
2-low fuel pressure,plugged fuel filter or weak pump

Both will not necessarily set any codes and is only apparent at higher speeds.
 

ptsb5a

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How come there isn't a fuel filter listed for an '05? Does Jeep solely rely on a wee screen on the fuel pump pick up? Has anyone spliced a fuel filter in on later model KJs?

The OPs problem sounds alot like fuel delivery, aka, clogged filter.
 

tjkj2002

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How come there isn't a fuel filter listed for an '05? Does Jeep solely rely on a wee screen on the fuel pump pick up? Has anyone spliced a fuel filter in on later model KJs?
Right from the '05 FSM.................

FUEL FILTER
DESCRIPTION
The fuel filter and fuel pressure regulator are combined
within the fuel pump module assembly. They
are not serviceable.

Older KJ's have a replaceable fuel filter.
 

mberthia

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found out what my problem was - a year later. I got a check engine light so I checked the codes. It was P0122 which can indicate a bad TPS and P1299 which could be caused by a vacuum leak. I found a vacuum connection where the rubber was cracked/rotted. I replaced that first but code the codes again so I change the TPS. So for now no more problems.
 
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Banditsteve

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Maybe just a bit of water in the fuel? I wouldn't worry too much unless it becomes a regular problem. Interrmittent faults are a pia to find. Much easier to find a permanent fault so just let things develop and take it from there? Steve
 

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