Starting Woes

[neohic]

Did some running around in the Eliminator this morning and it seems to have picked up yet another annoying habit. When turning the key to start, it'll turn over just as usual (several more times than what is desirable... typical Renix) but then it seems like everything cuts out then restarts the whole process. Have a look:

It doesn't do it everything, but I will say that it does it more when I'm running around from place to place shutting it down and starting again. Sometimes it'll do it just once and sometimes the starting lull will occur multiple times when trying to start. At its worst I counted out eight times before starting the engine. Not sure where to start with this. A few years ago when the engine was built, it got a new starter and CPS, the fuel pump relay lost its 12 volt supply (still not sure why... ran another wire) that was repaired, the battery was replaced about a couple years ago, and the starter relay was changed out when I got the truck about seven years ago.

I'll be honest: I'm getting fed up with this truck. From random wiring issues, to the leaking fuel rail fix only to have a valve cover leak start, or the windshield leaking leading to finding a little rust that'll only come back, breaking an a pillar cover, and a roof that's scratched to hell, then the windshield still leaking and making a soggy sponge out of my headliner again, and now this being its latest gift.

Unfortunately, I won't have much for time to look at it this weekend so I'm hoping that someone will read through this and will have had the same thing happen and know what's up. This does get me thinking though... would I be better off leaving well enough alone and keep the Renix or swap the whole harness and HO components from my '91 (the '91 is getting swapped into something whether it be my Eliminator or my '89 that the wiring is all kinds of a rat's nest) when I've got the time and place to really dig into it? Either way... any ideas on the starting issue or opinions on an HO swap are greatly appreciated. Thanks dudes.

[cruiser54]

Acts like a weak battery. How old is it? When is the last time you serviced the battery and cleaned the cables?

 

Ever refresh all your grounds?

[deziped]

I had similar prolbem. Would crank and start but immediately die. However, if I held the key in start position for about 2 seconds (couple revolutions)when

it began to chug it seemed to give it the incentive to keep running and all was well unti it acted up again. I finally think I have found the problem (fingers crossed) at the MAP sensor. Suspecting a vac leak I pulled the elec connection apart & replugged it, I then started the engine & pulled the

vac line off and when I put it back on the engine RPM dropped by about 250 from what it was prevously idling at. I've had no repeat of the annoying false starting since that time.

And at he lower RPM it actally starts a litle quicker and quieter. Weird stuff happens.

[Pete M]

have you tried wiggling things while it's running to encourage a stall? like the ignition key?

[neohic]

Acts like a weak battery. How old is it? When is the last time you serviced the battery and cleaned the cables?

 

Ever refresh all your grounds?

 

The battery is not quite two years old. I've been reading up on beefing up my grounds, but I have not done so yet.

 

have you tried wiggling things while it's running to encourage a stall? like the ignition key?

 

I have not. Again, this just started without proper time to investigate. Thanks for all the suggestions from everyone.

[cruiser54]

At a bare minimum, you need to service the battery connections and refresh your grounds. for under $20 you can add some grounds easily.

 

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

[HOrnbrod]

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

 

:agree: Installed Jon's mains cable upgrade years ago at the same time I upgraded the stock 90A ND alternator to the Mopar 134A alt. Have since added many hi-amp draw upgrades with the appropriate individual circuit harness work, and the battery is still going strong for 5+ years now.