My 1989 Jeep 2.5L 4-cylinder will run ok for 30-40 minutes, then it starts to lose power and bog down, and will eventually stall if I don’t stop and let it idle. It will idle ok, but has no power unless I shut the motor off and wait 5 to 10 min; the it will run for another 5-10 min and lose power again. The longer I let it sit (motor off) the longer it will run afterward.
A friend suggested it might be the catalytic converter is partially blocked, causing a buildup of exhaust that takes a while to clear. Is that a reasonable guess?
If it is, can putting some acetone in my fuel clean that up somewhat? I have seen mixed opinions on this on other sites. The Jeep has 180k, I’m at least the 4th owner, and it has not been well maintained.
First, as soon as it starts to lose power pull into a parking lot and take off the gas cap. If there’s a big wooshing sound, it’s something preventing your tank from venting, creating a vacuum. It also could be a weak fuel pump.
If it was a plugged cat it wouldn’t take 30 minutes to start affecting the car, and it wouldn’t take any time to clear.
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A new catalytic converter might cost more than the Jeep is worth. That would be the last thing on my list to replace.
I also agree with some kind of fuel-related issue. Bear in mind, though, that a poorly maintained 34 year old Jeep is not going to get any easier or cheaper to keep running.
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I’d say your fuel pump is on the way out. Sometimes the first symptoms appear when the fuel pump is hot from running for a while. This happened to me on a 1997 Jeep, in fact.
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If it had a carb I would say it’s possible to have vapor lock. but I believe OP has a TBI fuel injection system. it could happen but would probably be rare. I would think it might be fuel pump getting hot and cutting off.
But others here would probably know better
Fuel pump is relatively new, but I didn’t think about a gas tank vent issue. Will try that.
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It is TBI, and the fuel pump is pretty new, but the idea of a gas vent issue is intriguing.
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I would also check the fuel pump relay. if the fuel pump relay has an issue, it will cut off power to the fuel pump Also, if a relay overheats, the electrical contacts inside the relay can short circuit; causing the electrical flow to stop. However, when the relay contacts cool, it will resume the flow of electricity.
If it is an Airtex fuel pump or AZ pump that might be your issue, I have had many come straight out of the box and not work, as well as have replaced many new Airtex/AZ pumps that failed in a week or less, sometimes a little longer…
You need to hook up a fuel pressure gauge to confirm or deny a fuel pressure issue, of course try the gas cap thing 1st, do the easy test 1st… swap fuel pump relay (as stated) with something else that is not require for the engine to run…
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