No injector pulse

I've searched and read endless theads for two nights.
89 XJ limited
Drove fine to work in the morning. At lunch it had a slight missfire when I started it, but I drove it thinking it would clear up. About 1/4 mile later it just shut down.
It has good spark and good fuel pressure at the rail but I can't get a pulse from the injector plugs.
I tried testing it with a volt meter, test light, and LED bulb. I tested across the 2 pins and from possotive pin straight to nevative on the battery and I get nothing.
Is there a better way to test it?
What could go bad that would cause this?

Thank you,
Chad

Cam sensor in the distributor. Maybe CPS, but that is mostly responsible for spark.

Just changed the crank sensor recently and it tests fine with the meter and I have good spark. How/where do I test the cam sensor?

Thank you!

Ok, here's how the site says to test it:

"RENIX TEST PROCEDURE
1.Insert + voltmeter lead into BLUE wire at distributor connector.
2.Insert negative - lead into Gray W/trace wire at dist connector.
3.Set voltmeter to 15vac, turn key on & should show approximately 5.0volts.
4.If there is no voltage present - double check the backprobed leads to ensure good contact.
5.If there is STILL no voltage present; the Factory Service Manual says you need to "Perform vehicle test using DRB II tester. I don't have one. You don't either.
6.At this point, If you DO have voltage then remove / disconnect the ECU (computer).
7.Check continuity between the Blue wire and C-16 at the ECU. - If no continuity: repair harness wire.
8.Check continuity between Gray W/trace and pin C-5 at the ECU. - If no continuity: repair harness wire.
9.Check continuity between Black wire and "ground". - If no continuity: repair harness wire.
10.While observing analog voltmeter (That's one with a needle, folks! Your average digital meter won't show this...) crank engine & voltmeter needle should fluctuate back & forth while engine is cranking over. This confirms stator in distributor is 'pulsing' correctly and sending signal out for ECU.
11.If there is no sync pulse you will have to replace the stator by removing and dissassembling the "distributor" following the service manual procedure. * - Helpful Hint: Before pulling your distributor... "bump" the engine until the rotor is pointing straight forward and aligned with the side of the engine. That way you'll know where the rotor needs to end up pointing after reassembly."

In step 10 it says to crank the engine and observe voltmeter needle, but it does not say which wires to probe while doing so????

Well, I've tried testing the Cam position sensor as best I could and with the key on I get a fluctuating 1 t 6 volts (usually around 2.5) Does this mean it's bad?
I can't test while cranking because I don't have an analog meter

I had a similar problem with my 94. Not sure if it's the same wiring setup as yours, but it might be worth a look. You can probe the wire before the splice and see if you have pulses. If so, there is a break between where you probed and the injectors.

Where the wire harness drops down from the firewall to the plastic channel above the injectors, I had a broken the main connection that runs the injectors. There is a big 6>1 crimped and potted connection in there and I guess with time and vibration, it finally broke. Actually happened after a day of wheeling and I was on my way home. Stabbed the gas and I guess the movement of the engine broke the connection and I was stuck. Once I figured out the problem, it was an easy fix.

I think yours is opposite mine. On mine the the injectors share a common ground with separate power wires that are pulsed by the ECU. On yours I believe they share a common power source and are grounded by the ECU to fire them.
I have tested my grounds and they are good, almost zero resistance. Allthough I guess it's possible, I find it hard to believe that all of the power wires would break at the same time.
I'm still thinking it may be the cam position sensor, I just can't verify it through testing and I hate to buy the part just to see if it fixes it.

HELP!!
I just installed a reman distributer with a new cam positions sensor (cheaper than just the sensor itself???) and still won't start.
I'm at total loss here. Any ideas??

I'm thinking maybe I should just sell it as a parts vehicle, if so, what do they normally go for?

chad said:

HELP!!
I just installed a reman distributer with a new cam positions sensor (cheaper than just the sensor itself???) and still won't start.
I'm at total loss here. Any ideas??

I'm thinking maybe I should just sell it as a parts vehicle, if so, what do they normally go for?

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A bad stator in a Renix will not keep it from running. It just makes sure the injectors fire sequentially with the firing order of the engine. In the event of a failure the ECU will "batch-fire" the injectors. Most people never know they've got a bad stator. I only find it with my factory DRB tester when I'm scrolling through looking at what each sensor is doing.

Have someone crank the engine over while you wiggle the wiring harness that supplies the injectors.

Are you getting spark?

yes, I'm getting good spark.
I tried wiggling the wiring harness while cranking for quite a bit and nothing.
Had a friend say that all the capacitors (?) in the ecu that fire the injectors on his supra burnt out all at once one time, is that something I can check?

On my 89 MJ I only injector pulse while cranking, when i would let off the key it would die.

I replaced the starter relay(dealer part only). its the silver box next to the relay center, pass side engine bay.

I still do not know the relationship of the problem and the fix. I took the old relay apart and do not see anything obvious with it.

xjtrailrider said:

I replaced the starter relay(dealer part only).

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future reference: BWD #S4905 at your local Advance (kinda proud of it, though @ $35.00)

Shorty said:

future reference: BWD #S4905 at your local Advance (kinda proud of it, though @ $35.00)

Click to expand...

I haven't been in a AA in a while. Checked Oriellys and they could get it but it would take a while. The dealer had some NOS on the shelf.

The easiest way to check for injector firing is by using a NOID light. If you really have good spark, there isn't much other than a bad TPS or ECU that will cause a loss of injector drive. If the TPS is reading like a WOT, then the computer reads that as you trying to get rid of a flooded condition and shuts down the injectors.

You can also test for lack of injector drive, but everything else working, is to use some carb cleaner or ether down the intake. If it fires off momentarily, you have a fuel delivery problem.

I would use a DVM to test the TPS is working.

I do have good spark, and it will run if I spray starting fluid down the intake.
What's a Noid light and DVM?
How do I test the TPS, I had no idea that could cause it.
Thanks old man!

chad said:

I do have good spark, and it will run if I spray starting fluid down the intake.
What's a Noid light and DVM?
How do I test the TPS, I had no idea that could cause it.
Thanks old man!

Click to expand...

Old Man makes a very good point regarding the TPS possibly being in "flood clear" mode.

PM me your email address and I'll send you simple instructions on how to test/adjust the TPS on either the engine or trans side of it with a simple voltmeter.