javatrooper

Just swapped in a 4.0 ho from a 92 Larado into a 93 Sport. Both engines ran before the swap. At first, I didn't get spark from plugs but I did get spark from the coil. After two days I go back out and no spark from the coil now. Bench test both coils I have and just a little off spec but I know they are good. Even so...

I bought and installed new cap, rotor, wires, coil, and crank position sensor. Nothing. Swapped back my old distributor for the 2nd time to change the cam position sensor. Nothing. Dist not 180 degrees off, like that matters for producing any spark.

Tomorrow I will try to borrow an analogue volt meter and test the cam position sensor. Will also try and swap computers. After that, I have no idea where to look.

Any ideas?

sandaddik2

stupid thing that i did when i put the motor in mine, theres a ground wire for the motor, and without it grounded you wont get spark, is there a chance that you forgot to bolt it down like i did? iirc its close to the distributor.

javatrooper

Actually, my ground comes off of the back of the head and I had forgotten to tighten the nut thinking I could do it after dropping in the engine. Of course I can't reach it now so I had fabricated another ground coming from the front of the head. I have already checked the validity of this home-made ground and it is fine. Even checked the ohms from sparkplug hole to firewall. It's a good ground.

Thanks for the reply though.

This morning I checked every fuse in the car with my ohm meter. All fuses good.

I need to confirm my cam position sensor is working. I think the center blue wire is ground, but I need to know which wire is the positive. I have a light brownish wire and a red wire. My diagrams are for a grand cherokee and it has different colors.

Also, is there a test I can use to confirm proper voltage is getting to my coil? One terminal has around 11.6 volts and the other is around 3.4 or something like that. This is with the ignition on.

alpine.adrenaline

Make sure your CPS is getting a good signal; check the gap in front of the sensor.

javatrooper

Not sure how I can check the gap but I think I read of a test to check it through the wires.

Also, can anyone tell me the color of the positive and negative wires for the cam position sensor? I have a light brownish or off-white, an light blue in the center (which I think is ground) and a red wire. My diagram is for a grand cherokee and is different colors. I want to confirm it is working.

I also confirmed my home-made block ground was good. It is

And I ohm tested every fuse in the car, all good.


On my coil, I get a reading of 11.06 volts from one side of the connector. the other side had a reading of 2.6--2.7. It would fluctuate as my fuel pump relay clicked on and off. (this is another problem that I thought was unrelated that began after the swap) when I unplugged the relay the reading went to 3.0 volts and held steady. The voltage never goes away. Does this sound right?

I'm trying not to buy a new fuel pump until I at least get a spark.

How can a clicking fuel pump relay and clicking fuel pump prevent spark?

Crunsch

Crank position sensor went out on me the second time I ran my 96 cherokee outta gas. No spark for a few days first time I did it. Put 2.5 gal gas in and it started right up. thought it was gas issue.

Second time left me dumbfounded for a week wondering why there was no spark....pfft

Somewhere the fuel pump is in line with the vehicle getting spark ...cps to me sounds like your issue. I did all the stuff you listed above. When I heard on here about cps being a probability, swapped it and vroom!

It maybe connections to it... ?

JJaycXj

dont feel bad my oil pump drive broke off spun around and smashed my cam sensor

javatrooper

Just got a hot tip from another forum. My coil is getting voltage from both connections. Somehow the clicking in my fuel pump relay is connected the the no spark. The ground to the coil is getting voltage I presume from the fuel pump. Both are connected to the fuel pump relay and the auto shutdown relay. Somewhere there is a pinched wire crossing over. Either that or a bad pcm.

sv41878

[QUOTE=javatrooper;642952]Actually, my ground comes off of the back of the head and I had forgotten to tighten the nut thinking I could do it after dropping in the engine. Of course I can't reach it now so I had fabricated another ground coming from the front of the head. I have already checked the validity of this home-made ground and it is fine. Even checked the ohms from sparkplug hole to firewall. It's a good ground.

There is another ground that connects to one of the stud bolts that hold the coil and is around the same wires as the alternator and starter run on and that must be grounded.
From my experience with car amps, if your ground isn't right, you can get power to the amp but as soon as its worked (bass hits), the ground becomes insufficient and shorts. Could be the same issue your having. Coil ground is good for a test but insufficient under load.