Firestorm500

Every once and a while, my '87 4.0 Renix will not crank for no apparent reason.

My daughter, who lives 225 miles from me, drives this Jeep most of the time. She says the clock, radio, lights and buzzer will all work, but no cranking or clicking at all sometimes.

She says it does this about every 3 weeks to a month. Weather or temperature does not seem to be a factor. If she waits 3-5 minutes, it will crank and start easily.

It has been to the Jeep dealership at least 4 times for this. It is there now. Parts replaced so far include reman starter and solenoid, all new heavy duty battery cables, and several batteries as tests. There is a brand new one in it now. They can't seem to find a cause for this. Naturally, it starts every time for them.

I'm getting tired of paying for expensive rental cars for her. My next item to replace will be ignition switch. Anybody got any thoughts on this?

plotski999

Sounds like a crank position sensor to me, pretty common to go on these.

cruiser54

It's not cranking, not cranking with a no-start.

Here's what I would do if it were mine before spending another nickel on it:



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

DFlintstone

??? I'm a little confused. Firestorm, with 1,100 + posts...you did check the NSS? (they get gummy). Maybe I missed something.

If she holds the key over on start, and jiggles the shifter in park or neutral and it starts, that's the (common) problem.

http://bc4x4.com/tech/2010/jeep-neut...ty-switch-nss/

Good luck!

Firestorm500

If a crank position sensor goes out, the engine will crank forever without firing. My problem is no crank at all. Occasionally.

Thanks for the suggestion.

Firestorm500

Thanks for the suggestion. She has tried holding the key in start and moving the gear selector over it's full range. It didn't change anything.

Firestorm500

Cruiser54: Thanks for the great article. I am going to fax or e-mail it to the Jeep dealer tomorrow morning first thing.

I'm not trying to insult them, but even their Master Tech hasn't found the solution yet.

DFlintstone

You could try swapping the first and third relay. In intermittent AC problem would be better this time of year!

http://autorepair.about.com/library/images/bl347lib.htm

Firestorm500

Yeah, I spent over $1000 on that A/C in the summer of 2010.

And a little top-off in 2011.

That sucker had better work. It has been record-breaking summers here for '10 and '11. 114 degrees for an all-time record high here August '11. Heat index was 128.

DFlintstone

Ha! Hope she appreciates that. Mine was non-op for years. Finally got a kit of something from Napa and it mostly worked! ($45). Was mostly for that old dog there<<.

tjwalker

That is a good technique, but it doesn't completely rule out an NSS issue.

What would though is "bypassing" the NSS with a jumper wire. That would tell the story conclusively.

And yes, GROUNDS!

DFlintstone

X2 ^^ Re-reading I see "moved the shifter through the range". Not quite the same as jiggling it on the spot. If it's sticking in gummy grease it might need a little more persuasion. If that worked just once you would know. Then you could send another fax to those guys who specialize in adding an extra "zero" on your bill!

Also I believe there is an adjustment for the switch on the column. The rod from the cylinder goes down, and the switch below can be moved up and down.
Could be barely out of adjustment. I believe Cruiser said moving it down would help it make the connection. I might have that backwards.

If you have voltage and no click, the battery and starter are not even in the picture.

darknezz

def not ckp, when mine would randomly start doing that it was the started, it would occasionally not crank with no sounds, voltage fine, if i sat for awhile it might start. I started tapping on the started and got it to work when it did its thing. started was like 50 bucks new from AZ

just another thing to check

DFlintstone

Whoops! Too much caffeine? Swapping the fuel pump relay won't help with a "no crank". Hope I didn't cause any hassle.