Data Logging Help

[79jeepincj7]

Yeah sorry to many motors.

The amc 360 is in my g/fs cj

The carbed 350 is in my cj.

This is a 95 tbi 350 in my buddies cj. So I'll leave the timing alone

[79jeepincj7]

Hey Bill, so working on my buddies cj. 95 motor with a 90 harness. I cut the TPS and changed the end to make it fit the 95 engine. I have both harnesses.

I went through all the voltage checks and everything checks out, went through all the first step procedures. I have 12 volts to the injectors, 12v to the coil etc.

When the engine is turned over there is no spark to the plugs or a 12v circuit in the injector leads. So for some reason the computer isnt grounding the injectors or telling the motor to spark. Could that be a bad ecu?

Thanks!

[Bill usn-1]

You must have spark before you will have injector fire.
You can unplug the ecu and still have spark.
Spark only needs the distr, ign module and coil.
The ECM only provides timing control after the engine hits about 400 rpm. It has nothing to do with spark.

So fix your ignition then move on.
Do you have 12v during cranking or only when the key is in the on position?

[79jeepincj7]

Ill have to check that, but its the same 12v wire that use to go to the + on the HEI disy from the old motor that was in it. And it worked for that.

Also it sparks for a second when you let off the key from it turning over. I remember reading something about that once but I dont remember what.

But thats what I told Dave, that I thought it might be the ECM/ECU in the distributor. So I guess thats what I gotta try next IF its not just a 12v during crank issue.

Say I DO have 12v during cranking just for diagnostics sakes so I have a whole list for tomorrow what else. Is there any way I can test that module or the coil?

[Bill usn-1]

Best to just take the ICM-ign cont module to the parts store and have them testedabout 3-5 times. f they fail at all then they are bad.

Coil is checkedwith an ohm meter.
It should be less then 1 ohm from + to -
and very high resistance from the + to coil wire.
Your using the GM coil right?

And the ICM is mounted with the thermal paste.
and you can read the pick up coil in the distr with the meter.
IIRC it should be about 500ohms. specs are in the FAQ's

[79jeepincj7]

Yeah it the gm coil with the small cap distributor. The whole tbi motor is still stock and complete. But I will check those things out tomorrow! Thanks!

[79jeepincj7]

So after doing all those checks with everything passing i checked the 12v switched wire while cranking and it drops to zero. Jumped 12v to it from the battery and it fired right up.

So thats the problem. So then I went through his whole fuse panel and not one switched 12v stayed 12v. What is causing this and how do i find one or make it so it does?

[Bill usn-1]

You can't check it at the fuse pnl.
There should be one post on the key sw that originally went to the coil to provide 12v in crank and run.
You need to look there.
The fuse pnl is 12v in run only.

Doesn't the wiring FAQ specify 12v in run and crank??????

Didn't we discuss this earlier?

You must have spark before you will have injector fire.
You can unplug the ecu and still have spark.
Spark only needs the distr, ign module and coil.
The ECM only provides timing control after the engine hits about 400 rpm. It has nothing to do with spark.

So fix your ignition then move on.
Do you have 12v during cranking or only when the key is in the on position?

[79jeepincj7]

I used the wire he had to the to the HEI that worked to start that. So I took his word that it was 12v when starting. But the harness had also been hacked before him. So thats why I checked to see if he really did or didnt have spark during cranking like you asked. So took what we had discussed before to figure this out. My question was where does the constant cranking 12v come from. But you answered that will one of the pins from the column so thanks!!

I will find that pin tomorrow and wire too it. Thats what I did today was search for the wire in the harness that has the 12v when cranking but didnt find it anywhere so i tried the fuse panel too.

I will go right back to the column and start from there.


Thanks!

[Bill usn-1]

You gotta luv PO- previous owner wiring mods!
Good luck.