93 YJ Running Horrible

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RI93YJ

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Joined
Aug 24, 2022
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7
Location
Rhode Island
Hey All! New guy here but long time reader. Been doing a bit of work on the jeep lately and I can’t figure this one out. Any help is greatly appreciated! :)

Saw a small fuel leak by fuel filter and was running rough with a very low idle. Replaced fuel filter. No dice.

The gas tank skid plate was rotted so I figured I’d get a new one, do a new fuel pump, run all new fuel lines…and this would fix.

Finally got that bear of a project done. Issue persists. I never looked for a CEL as the fuel leak was a physical clue. I should have though. That was bush on my part.

Today I checked and it was throwing a Code 14: MAP sensor circuit open or shorted; voltage too low.

I checked for the 5VDC at the MAP plug and it was there. So I replaced the MAP sensor with one from NAPA.

Now the jeep wont start at all. :/ I ohmed out all fuel injectors and the are all good. About 14.6.

Any one have any insight? Maybe vacuum leak?
 
Lil more info…brain fog today.

1993 YJ 4.0 with about 170k miles

Ive owned it a few years and been going through it. Dont drive it much.

New plugs, wires, distributor, cap/rotor, starter, TPS.

One weird thing that happened right around the time it started running rough…when ever I start it, the windshield wipers go on n off a few times when the switch is off.
 
RI93YJ said:
Lil more info…brain fog today.

1993 YJ 4.0 with about 170k miles

Ive owned it a few years and been going through it. Dont drive it much.

New plugs, wires, distributor, cap/rotor, starter, TPS.

One weird thing that happened right around the time it started running rough…when ever I start it, the windshield wipers go on n off a few times when the switch is off.
Click to expand...
Are you getting pressure on the fuel rail? I’m assuming you changed the filter same time as all the lines. My next thought would be fuel pressure regulator. Is this the 6 or 4 cylinder, I’ve got a 93 with I6 and 127,xxx miles
 
Thanks for your reply!

I need to rent the fuel pressure test gauge again. Last I checked, it went to 40psi but then dropped. Losing pressure somewhere. Its gotta be a bad FPR or a clogged injector that failed open. New injectors on the way. Ill throw a FPR in too while im at it.

Its the 4.0 6 cyl. And yes I changed the fuel filter out during the new fuel line project. Once I get this fixed I will report back with what the problem was. Driving me nuts haha

Any other thoughts are welcome and appreciated. Thank you :)
 
RI93YJ said:
Thanks for your reply!

I need to rent the fuel pressure test gauge again. Last I checked, it went to 40psi but then dropped. Losing pressure somewhere. Its gotta be a bad FPR or a clogged injector that failed open. New injectors on the way. Ill throw a FPR in too while im at it.

Its the 4.0 6 cyl. And yes I changed the fuel filter out during the new fuel line project. Once I get this fixed I will report back with what the problem was. Driving me nuts haha

Any other thoughts are welcome and appreciated. Thank you :)
Click to expand...
I’m not a 100% but you could remove all the injectors from their ports, unplug the coil wire, have a buddy bump the key over and look for a inconsistent injector. Poor man’s pressure test. The FPR isn’t cheap but could easily be the culprit.
 
Ah yes that is a good trick! I found a set of 6 brand new OEM fuel injectors on ebay for $185. I couldnt say no. Im sure they are old and its worth throwing new ones in.

I do see FPRs vary widely in price. Cheapos for $15 all the way up to 90-100 for what seems like respectable quality.
 
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