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-   -   90 XJ wont start (http://www.jeepforum.com/forum/f11/90-xj-wont-start-1300344/)

T-BirdJeeper420 12-12-2011 05:10 AM

90 XJ wont start
 
greeting again jeep forum members! here is the problem

i use this jeep for work so it runs everyday, it also has a rebuilt motor in it with less than 20k on it, inspected etc, i keep her running nice

yesterday i noticed that when it went to start it did that low batt slow roll over for just a second and then started up normally (i just put in a new batt last month, the headlights are strong etc etc etc)

this morning when i went to start it i got nothing, it will not turn over at all.
now to the best of my knowledge when u turn the key to the prestart position u should be able to hear your fuel pump prime for a second and then shut off. this is not happening, instead u can hear the fuel pump continuously prime, except ONLY while the key is being held in the START position not the prestart position

i rolled under it and tried to jump the starter with a screw driver and arrived at the same thing, the fuel pump will just continuously prime with no attempt to roll the engine over

i am a great fixer lol and not so good at diagnostics so any help on locating the issue would be awesome, if you need anymore info dont hesitate to either post it here or PM me, im sure if we put our heads together we can figure this out ;]

DeepDirtJeep 12-12-2011 07:43 AM

Seems like a short time for the battery to die. Have you tried to jump it or charge it? Kinda sounds like some kind of parasitic loss. What was your voltmeter reading the day before it died?

T-BirdJeeper420 12-12-2011 09:31 AM

i didnt test it yesterday. im going to try and jump it when my girl gets home with her jeep.

the only strange thing i saw was when u turn the key to the prestart position and the gauges come online that the batt gauge reads inbetween 9 (far left) and 14 (middle of gauge) but only just a hair past the red margin of 9 instead of 14+ like it should with everything being normal

i can crank my sub, my high beams are strong, etc

T-BirdJeeper420 12-12-2011 03:45 PM

Figured it out. Bad batt, thx for the advice. It must have been defective or something

cruiser54 12-12-2011 05:38 PM

Do this when you get a chance:

Renix Ground Refreshing

The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.

The components grounding at the dipstick tube stud are:

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.

The factory was aware of the issues with this ground point and addressed it by suggesting the following:

Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.

Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.

While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.

Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.

First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4” socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.

A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18” long with a 3/8” lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.

A further improvement to the grounding system can be made using a #4 cable, about 10” long with 3/8” terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.



If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.


Revised 11-28-2011


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