Jeep Strokers

So I've been lurking here for years now. And now that I'm getting close to running things I've started posting.

Here is what I have:




87 block, bored .030 over With 12 counter weight Crank and 4.0 Rods.
KB944 with Deck milled to not quite zero (I think it's 0.010).
.043" headgasket
Block Girdle with hardened washer for clearance.
Cam is CompCams 68-232-4
7120 heads, milled to correct warping.
3 angle valve job on the old valves and new valve guides.
CC'd the head for ~61CC volume.
Mopar Springs, locks, and retainers. Stock rockers
99+ intake manifold and 94 Throttle body.
24lb hr injectors.
TPS is adapted but will need to be revisited later.
Oil catch can and a Donoldson 6637 Air filter (Which is over kill but i had one so..)
Refreshed all the grounds and positive Voltage distribution.
New Distributor cap, button, and plug wires.
I broke the old CPS removing the Engine so that is also new.
the gas sat for six months and evaporated so I have ran new gas to a catch can to avoid running trash in to my new lines.
Gas is 93 Octane 100% gas.
Map Adjuster running at 5.4V because I have no Idea what it should be, and don't have a Wideband o2 to measure.
This is all running on the Famed Renix system
I've been going through several forum's renix tips and have things pretty well understood.

I say all of this because when I FINALLY got fluids in it and the nerve to turn the key I get the classic Crank, no start. I haven't verified that there is no spark or fuel yet. But it doesn't even try to stumble. It just cranks.
All the Symptoms point to the CPS. When I measure the CPS (on Pins D1, an C1 at the ECM) I get (consistently) .62VAC. I don't think the CPS is the problem.
I've found one more thing where I can measure the spark dwell at the ICM to see if the ECM is doing it's job. I find it hard to believe but I suspect the ECM may be faulty.
I've got family obligations and school, the will keep me from finding out in the near term but I'll post it up when I find out.

Get the 3 or 4 ground wires hooked up at the engine dipstick tube stud? Clean and shiny?

Thanks Cruizer I'll double check the Grounds at the dipstick again when time allows.

I was able to sneak into the garage and check things I had 4.8 VAC last night (likely because I've started to drain the battery). But just to completely rule out the CPS in my mind I drilled the mounting holes larger. Now I'm see 1.1 VAC on the CPS. I almost wonder if it's close enough to contact the flexplate. I went through Cruzier's Renix Tips and checked for a 5V square wave at the ICM. NOTHING. I actually have a spare ECM from an 88, that a swapped in. No change. Now I'm back on the original ECM. So It's has to be electrical. Sounds like the best advice is to check grounds.

Something strange worth noting. Sometime the Parking Brake warning light will be on at key on, some times it's off. Sometime it turns on when Cranking. It's probably worth mentioning that the parking brake set, and I'm not changing anything there. So that's another symptom I'm going to chase down. But it'll probably be next week before I can check anything else.

Got back to it yesterday. I checked the grounds on the block. The paint is ground down to bare metal where the terminals contact.




So now I'm lost. Hopefully some of you can offer some assistance.

Here's a list of things I've checked:

TPS engine side 4.9 Reference, .87 signal. that comes out at 17.7%
Grounds at block are good
I added the instrument panel ground yesterday.
tested MAP with Vacuum gauge, 4.7V at 0" hg, .253V at 23.5" hg
CLT and AIT are both reading expected resistances
1.7 VAC on CPS while cranking (seems high, any thoughts?)
NO Square wave at Ignition Control Module Timing IN
+12Vdc on A at ICM, Ground continuity on B at ICM
Fuel pump primes for 3-5 seconds, then shuts off when keyed on.
Grounds at fuel injector connector are good.

I tested the ECM harness a bit and found this:

B7 battery +12Vdc
B8 Ignition +12Vdc when keyed on
B10 Zero volts (ECM disconnected to test... so that makes sense)
B11, B12 0.2 Ohms resistance to Engine block ground, battery terminal, and Instrument panel.
C3 Start Signal ~10VDC while Cranking
D1 is not common to D3 on the harness side ( is that normal?)
D10 Injector Feed ~7V while Cranking
C11 I forgot to measure.

Questions:
Are D1, D3, and C16 normally open with respect to one another?
Is the CPS too high reading 1.7VAC?
Is D10 reading 7V normal? Is that due to the starter draining the battery, or is that an issue?

The beast ran in July when I pulled the engine. I don't expect any issue with the ECM, but what does the Jeep Strokers community think? I'm loosing sleep over this literally. Any help is appreciated.

Can't have too high of a CPS signal IMHO.

Coil/ICMs can act funny at times. Ever swapped it for a known good one?

I haven't tried swapping coils yet. I am not getting the trigger in from the ECM. Is there anything else the ECM needs to see before it will send the trigger signal to the ICM?

Pretty sure it's just CPS signal.

Refresh me. Did you check CPS signal at the ECM?

Here's why I ask.

Some of these Jeeps got a cPS bypass done at the dealer.

A new plug for the CPS was wired via it's own harness to the ECU. Part of the procedure was to clip off and tape back the original CPS plug. If that wasn't done, you may have 2 plugs on your Jeep and you're plugged into the useless one. Just a thought.

Here's the best link I could find for the TSB.

http://www.justanswer.com/jeep/1gq93-19 ... l-not.html

Thanks Cruiser. That link is interesting. I may put a shielded drain cable on the CPS if I still have trouble out of it.

I just confirmed the the CPS at the end connector.


I'll figure out how to post a video and post up the oscope.

But it looks like the CPS is working. I'm now digging into wiring and relays.

Any suggestions are welcome.

Still not starting. The amount of time I spent researching this at work is probably a terminal offense. BUT I learned new things about the RENIX wiring, most of which is likely wasted on this forum. Here goes anyway.

I found that the ECM Primes the Fuel pump with the normally open contacts of the O2 sensor heater relay. That is the 3-5 second you hear at key on. Of the three drawings I found on the web, two of them do not show this connection. Honestly most of them don't show the ballast resistor either. Also worth noting, the Starter relay supplies +12VDC to the Fuel pump directly with the Key in start. I was so sure that I had power to the Fuel pump relay , and now I'm starting to suspect it's wiring.

I found increasing resistance between the ign switch,the two harness splices, and the Injector feeds to the ECM. The first one is labeled "yellow" and is three ohms from one side to the other. The second is "Orange" and adds another 13 ohms. Once I address this that will bring my voltage back to 12V on the Injector feed pins of the ECM.

The last thing; I need to find a way to test the latch relay, Fuel pump relay (87 to ECM injector supply), both with Key on and again while cranking WITH the ECM connected.

Okay so during the start sequence with key on the fuel pump primes. With key in start the fuel pump runs. Does the ECM latch the fuel pump and latch relays next? Or does it do that after it sees the 300 rpm?

I'm just waiting for someone to chime in and tell me I should just get an HO with OBDII...

So the fuel pump quits running when the key goes to On?

I have to verify. I thought it was running cause I heard it priming. But all I can hear is the starter otherwise. Hopefully I'll have time this weekend to look at it.

Started digging today.. Found five more of those stupid factory duct tape splices. I'm going to hope that my problem lies there. Once I get enough time to fix those we can revisit the other issues.

On a side note the person responsible for duct tape wire splice insulation at AMC in 1988 (when mine was built)... Should be shot.

Mexicans. Doing what they were told by AMC.

and bTW, great idea.

I've reworked all of the Meixcan's Handy work. It does what It's told I won't shoot the messenger.. I've still got to put the battery tray and battery back in. But right now I've got to go get my littler helper to sleep...

So quick update. Put the battery back in. With the Harness splices repaired the Fuel pump now sounds much more authoritative when it prime, at key on. STILL CRANK, NO START! I didn't have much time. But i did measure 5 VDC (checked in AC and it showed 0V) at the small yellow wire at the ICM. That should have been a 5 V square ware right? Another Quick observation... I now smell fuel. Definitely. The tail pipe smells like fuel. So that's good news.

So my plan:
Check the ICM timing in.
Is this a "true" square wave or does it just drop low for a millisecond to trigger spark? Do i need to hook up to a scope to see it?
Double check Plugs, wires, distributors.
The firing order is 15 36 24 (same as Cummings "Too young, too old, just right") so I know I've got the wires in the corrects places.
Maybe pull a plug and check for spark against the block.
I followed the instructions to the Tee on stabbing the distributor, but Maybe verify I'm not 180 degree out

Anything Else?