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88 xj stumbles when warm

timthecleric

NAXJA Forum User
Location
canton
I have an 88 cherokee that just recently came out of a long hibernation (5 years). I have finally got it running. It starts ok and seems to run smooth until it has been running 15-20 minutes. Once that happens, it seems to develop a stumble right around 45-50 miles that lasts a second, runs fine 2-3 seconds and repeats. It is almost as if the power just absolutely goes away for a second then reappears, even though there doesn't seem to be any roughness in the engine.

I've been running it just on little short 3-5 mile trips until I am certain everything works and encountered this issue on a longer set of errands. I've had it up to freeway speeds. But, this stumble when warm worries me a bit.
 
So, tell me about the fuel, and the varnish in the fuel system?

How did you clean it out?
 
the cherokee was put away empty on gas. i had run 5 gallons through it from a freshly filled gas can just to get it moving for a couple days and then to a gas station. i've also run some fuel injector cleaner through it. hadn't really considered fuel an issue as there are no abnormal smells, nor is there any smoke from the exhaust. that, and it takes so long running before it has the power loss issues.

i had been driving the short runs for probably 2-3 weeks before the first longer run opened up the stumbling/hesitation problem when warm.
 
Well, with the new ethanol fuel mix all of the crud that accumulated in your fuel system from the day it left the factory is probably coming loose.

Try changing the filter, see if that helps.
 
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