Yep-I pulled 1,2 & 3 to see if they looked any different. All looked about the same. I just sprayed with some carb cleaner but swapped #2 and #1. Same dealio. Exhaust has a good bit of smoke in it but oil looks ok-no coolant smell or anything so I'm not thinking head gaskets. I'm thinking about swapping out all the plugs with new just to be sure when I do the distributor cap and rotor. I ordered it thinking it was a spark issue but seems to give good spark.

This is my first Jeep-always had GM stuff. First inline 6 too.

It has a tendency not to start as well. Cranks fine and will try to start but then nothing which is why I ordered the CPS. Today, it started fine every time I needed it to when swapping plugs, injectors etc. Then, I had supper and went out to move it out of the way and it wouldn't run. Crank crank crank, nothing. Left it til tomorrow. Put the poor battery on the charger since it's not run more than 15 minutes in a row today but had 10 start ups or more!

 

I've got a new injector coming this week (off ebay) so I'm going to try that as well but I did swap them to see if there was a difference and still #1 is not #1 in my book today.

 

What did the injector ports on the manifold look like? Did you have a peek down there for signs of obvious blockage? I couldn't believe how disgusting the inside of my manifold was when I had it off last...glad I plugged that egr.

Also, this is just a shot in the dark, but making sure that injector has a good ground path might help.

I've also read of fellas who unbolt the rail with fpr and lines attached, and crank it over to watch all the injectors fire to look for the odd one out....safely of course.

Definitely interested to see how this is solved. Good luck, eh?

 

That's funny Hank. I woke up this morning pondering this problem and had been assuming the OP was testing the power to the #1 injector using the injector connector's ground. Perhaps he hasn't been and the ground in the connector or further down the line is bad?

 

could you post the cliff notes on Renix injector wiring and grounding? I've been chasing a similar problem, had an engine fire between TB and valve cover, got some crispy wires. Confirmed TPS voltage, swapped loads of parts (injectors, cap/wires/rotor/ CPS, IAC, ignition module, fuel filter)...starts and idles great, but still missing and stumbling under acceleration.

 

Hopefully this is what you're asking for. Two write-ups here and both worthwhile performing as they can only help and never hurt.



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
Cruiser’s Renix Sensor Ground Test
Set your meter to measure Ohms. Be sure the key is in the OFF position. Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS . The letters are embossed on the connector itself.
Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too.
You want to see as close to 0 ohms of resistance as possible. And when wiggling the harnesses/connectors the resistance value should stay low. If there is a variance in the values when wiggling the wires, you have a poor crimp/connection in the wiring harness or a poor ground at the engine dipstick tube stud. On 87 and 88 models, you could have a poor connection at the C101 connector as well.
Revised 05/03/2012

 

Thanks for your help (and the others). I was checking the power at the injector by testing it at the two terminals on the harness. I put the test lamp at those connectors as well. Is there a better way?

 

I should have taken the entire rail assembly off the Jeep and looked down the rail but all I did was remove the bolts and the fuel regulator and lifted it enough to remove the first three. I figured if the fuel is getting to the first three (#1-#3) then it's getting down past #6, #5, #4. There was no junk at the regulator (which is at the end) and I put a scribe into the #1 injector port on the rail and nothing was there. I could pull the whole rail again and blow it out or something. I was worried about the fuel quick-connect on the regulator not being usable after I removed it. Are you usually able to disconnect and reconnect at this point? I don't mind taking it apart again if the feeling is there is a blockage.

I did think about somehow having the whole think suspended in the air and running fuel through it but thought I would create some sort of inferno!!!

I appreciate your help with this. I put the battery on charge last night to start fresh. Also worked on light bulbs, the radio etc to have some sense of accomplishment and let the brain rest awhile on the engine issue. Just hoping I didn't buy a Jeep with an expensive engine issue. I'm avoiding taking it to a mechanic at this point as funds don't allow it at this point. Just trying to do most or all the work myself to get it to pass inspection.

Thanks to all. I'll keep you posted but please post any ideas you have as you think of them! This is a great forum.

 

I just wanted to be sure you were using the ground from the connector and not somewhere else. For instance, what if the ground wire in the connector was bad but you didn't know that because you had your test light lead connected to another ground point.

 

I've put the no-fire on the back burner for awhile while I fix a few other things but I'll add one observation as an update. When driving the Jeep, and giving it gas, I could smell some gas in the exhaust and if pushed with hard acceleration, it would backfire when you let up on the gas. I disconnected the #1 injector harness and then drove it the same way and it didn't behave like that (no backfire).


So, to sum up,
-adequate compression (evidenced by compression checks)
-I think it is telling me that it is getting fuel, the injector is firing but there is no combustion in #1.

I worked on the dipstick grounds and fixed those up and that seems to have fixed a random no-start problem I was having as well. I did disconnect the C101 connector and did a quick cleaning on that with brake cleaner and a pick. I may re-do that when I have time.

I was getting frustrated with this rough running so I've moved on to installing a new muffler (got all the bolts of the flange and the clamps!). No catalytic converter is present so hope that isn't causing any issues with back pressure. In Ontario, pre-1987 don't have to pass emissions testing so I'll put it back the way it was when I got it. The Cat seems to be around $100. Also, will be working on brakes and shocks as it seems to nose dive a lot on stopping like front calipers are grabbing but rear isn't but that could be shocks.

This time of year is busy getting all the yard work done, opening and maintaing a swimming pool for kids, baseball practice etc-Hard to fit in a demanding Jeep into the mix!!

 

Try adjusting your rear brakes after inspecting them. That could be your nose-dive problem. The self adjusters don't.........

Did you do all the ground refreshing or just teh dipstick tube stud?

How about the sensor ground test?

 

I've tried backing up and hitting brakes hard but I will take off the rear wheels and see what the adjusters are doing (if anything) or if the shoes/drums are shot. The brake light is on but the master cylinder is full of fluid. I can't see a leak anywhere from the outside (no drips or messy looking lines but once I take the back wheels off, I see if the wheel cylinders are leaking as well.

I just did the dipstick stud. Not sure what the sensor ground test is. Should I search that?

 

He posted it in here already.

 

I think I posted both write-ups in this thread in the same post. Do it all. No shortcuts or skipping steps cuz stuff "looks good".

Brake light on means loss of fluid pressure in teh system.

FWIW, self adjusters suck. You'll need to do a manual brake adjust on teh rear shoes.

 

Sorry-I thought the smaller font was part of your signature!

Cruiser’s Renix Sensor Ground Test
Set your meter to measure Ohms. Be sure the key is in the OFF position. Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS . The letters are embossed on the connector itself.
Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too.
You want to see as close to 0 ohms of resistance as possible. And when wiggling the harnesses/connectors the resistance value should stay low. If there is a variance in the values when wiggling the wires, you have a poor crimp/connection in the wiring harness or a poor ground at the engine dipstick tube stud. On 87 and 88 models, you could have a poor connection at the C101 connector as well.
Revised 05/03/2012

I will try this before the weekend. I have a spare TPS that a buddy gave me from his Jeep collection as well. I have been wiggling the C101 all the time hoping that was the issue.