I've searched around and haven't found anything similar to the problem I'm having so I'm starting yet another no start thread.

1989 XJ, blew out exhaust gasket on number one cylinder, replaced gasket.

Reassembled engine, started it up and it ran/ idled fine. Revved up a couple times and it simply died and now will not restart.

Battery voltage while cranking around 11.5 V.

CPS tested good using voltage method

TPS tested good

Tested for vacuum leaks and found none

Around 31 psi to the fuel rail while cranking

Good spark while cranking.

It will crank and crank without trying to start and I'm at my wits end now. Do any of you Renix guys have any other suggestions for me to try?

Anyone? I'm out of things to test. Have eliminated most systems. Could the PCM have taken a dive on me? Is there anyway to test the PCM without installing a "test" unit?

hhhmmmmm, no spits pops or anything?

Pops every now and again. Checked all grounds and they are good too. What should the voltage be coming out of map sensor?

3.5 to 5 volts i think.

Okay, thank you, I am receiving 5 volts from it so it should be good. All of my trouble shooting has lead me to believe that the pcm may have taken a dive on me.

AC volts.....

Pete, he was asking about output from the MAP.

Bender, I'd recheck the AC output from the CPS and it's wires. Granted it's sparking, but I would do that anyway. Maybe .35 could be considered minimum. I did see one that would run for a couple blocks with only .1. (I have .4)

Being flooded is one reason an engine with all "the right stuff", might not start. Maybe check some plugs for being wet. Also:

There is a brittle little tube. It comes out of a rubber plug, low on the engine side of the throttle body. It runs back to the firewall, then up to your MAP sensor sort of high up there near center on the firewall. CRUCIAL!! The MAP will tell the ECU to dump fuel with less/no vacuum. Any crack or blockage and it will be pig-rich. (black smoke, fouled black plugs). You can pull the line off the MAP and feel for vacuum with your finger. If it runs!

This here has some stuff on the MAP. http://www.lunghd.com/Tech_Articles/...iagnostics.htm Also there is a test where you use an analog meter, (with a needle), and a vacuum pump to watch for a smooth sweep of voltage. Usually trouble there is that tube though.


Check the info in Cruisers sig. These things can drive you nuts with bad grounds. That dipstick stud grounds all sorts of crucial stuff, including your injectors.

Okay, I've back probed my #1 injector to make sure they are firing and I don't get hardly any voltage to it 2.something volts was the highest I saw. The map line is plugged in and unobstructed. I can remove it, blow into it, and feel/ hear the blown air coming out of the throttle body. The plugs are clean, dry, and correctly gaped. I've triple tested the CPS using the AC Volts method and I get correct voltages while cranking. Double checked the MAP and the 5v supply is working correctly. While cranking, I'm getting 4.00 volts on the return wire (pin B on the connector). Triple checked the TPS following the procedure described in above link, it checks out just fine. Checked all grounds last night before I quit for the night and all ground circuits are 0.3 ohms or less indicating no problems with the ground circuit.

What else should I check.

I've got to run. Google "noid light" . Also I have a short thing on U-tube using a bulb from a mag light. (these check the power to the injectors).


Clean that gang of wires on the dip-stick stud, check Cruisers stuff, including sensor circuit resistance.

Did this harness get pinched/burned because it was routed improperly?

No, I looked at that again tonight. I've got it routed just as you have shown it in the picture.

Injector harness at the back of the head/intake manifold good?

Yes sir. Split the loom and checked it all over tonight and checked the crimps on the sensor ground circuit as well. This has really got me stumped.

I'll see if I can find a noid light and actually test the injectors correctly tomorrow.

Good plan. Get a good night's sleep.