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TJ Runs bad under load

993 views 14 replies 6 participants last post by  superboop 
#1 ·
I have a 1997 TJ with a 2.5L which throws codes for both 02 sensors so I disconnected them both and I can tell it runs a little bit rich but other then that no difference. It runs perfect at idle and WOT but backfires, pops, and has no power between 1500 and 4000 rpm while cruising or backing of the throttle. I replaced all the plugs, checked the distributor and it looked good. Would a bad fuel pump or clogged filter cause this? Thanks
 
#14 ·
I also bought it running like crap so I don't know how it ran before the 02 sensors went bad and yes it was worth buying with it running bad, its a '97 TJ with a 5" lift that I paid just a hair over 2k. The frame and body are perfect which is pretty rare for us northern Jeep owners.
 
#13 ·
Alright I tested fuel pressure and got a reading of less then 10psi. I don't know of any MPI system that can run with that low of pressure and my manual says anything below 30 is defective. So I dropped my tank and pulled the pump. When I had it out on the bench I got the pump seperated from the rest of the system and it pumped good like +40psi but when I went from the top of the regulator it again pumped to only about 12 psi so Im pretty sure my main problem is a bad fuel pump regulator. So I ordered a new module. Thanks for all the info, I'll update how it runs as soon as i get it in.
 
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