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-   -   1989 Cherokee 4.0 Barely runs (http://www.jeepforum.com/forum/f11/1989-cherokee-4-0-barely-runs-1498583/)

Trooka 03-24-2013 09:10 PM

1989 Cherokee 4.0 Barely runs
 
Ok, so I have searched the forums for days now. I have found similar problems but not exact as mine. my problem is my Jeep is barely running, it pops, backfires, spits, sputters, backfires through intake, well yeah thats about it. I purchased it 4 days ago, so far I have tried 2 different ignition control modules, cleaned intake, cleaned throttle pos sensor, cleaned IAC, replaced spark plugs, all have had absolutely no positive changes in the idle, or rev. I know the timing is non adjustable, but I didnt know that before and attempted to twist the distributor to adjust the timing. call me crazy but it did change it. it made is so the thing would idle but still any throttle at all it would fall flat on its face, and pop backfire and sputter. since then if I start it again it will not idle correctly again. tomorrow I am going to check fuel pressure, I also checked the resistance of the Crank Position Sensor it was within operating range. also the previous owner said it happened 1 month after the local mechanic shop replaced the clutch. when you try to start it now I believe they screwed something up in the clutch because it will make some nasty metal on metal noises out of the tranny/flywheel/starter. any help would be much appreciated!

bigbadduck 03-24-2013 10:50 PM

Sounds like your fuel pressure is too, check pressure at rail you should have 39 psi at idle. If pressure is low check fuel filter and pump.

sbaird95 03-25-2013 06:16 AM

Quote:

Originally Posted by bigbadduck (Post 15188725)
Sounds like your fuel pressure is too, check pressure at rail you should have 39 psi at idle. If pressure is low check fuel filter and pump.

x2... also check the strainer in the fuel pump, sounds like the problems i had when my strainer was clogged.

ComancheKid45 03-25-2013 07:28 AM

Check your map sensor and the vaccum line associated with it.

tjwalker 03-25-2013 06:25 PM

Actually the fuel pressure spec for an 89 is 31 psi at idle. Then disconnect the vacuum line leading to the fuel pressure regulator and the pressure should then jump to approximately 39 psi.

Be sure that the vacuum line is pulling good vacuum line and is not wet with fuel. If it is wet with fuel, you have a ruptured fuel pressure regulator.

If all that checks out, I agree with testing your MAP sensor.

Trooka 04-04-2013 07:49 PM

diagnosed...
 
so you guys are probly gonna poop chickens on this one. after EVERTHING checked out I decided to drop the tranny and possibly part it out. whomever replaced the clutch forgot to tighten and/or threadlock the flywheel bolts. at low RPM's the flywheen was off balance giving the crank pos sensor enough of a reading to run but not much else. so tighten and lock the bolts, put back together and tadah... 400$ jeep fixed. thanks a bunch for your help everyone. and im sure I will be needing your help again. hopefully not but lets be real.... its a jeep after all....

Simmbad 04-24-2013 10:30 PM

nice glad you fixed it


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