I have a 1997 GMC Jimmy and have swapped a GM Reman engine in the place of a bearing damaged engine. When I attempted to start the vehicle, it will crank but will not fire and run. I have searched the forum and found helpful tips on getting the distributor timed correctly. I had borrowed a Tech2 from work to help with setting the camshaft position, once running and used it to check the trouble codes while cranking the engine. I received 2 codes, P0336 and P0338, indicating that the crank sensor has issues, but I replaced it and the problem still exists. Does anyone have any thoughts on what to check or how to get this thing to fire up?

-Hiney

 

Have you checked the wiring between the PCM & the CKP sensor? It is possible that you damaged the wiring during the removal of the old engine or installation of the new.

Also, one thing that has come up in the past is that the aftermarket front covers do not allow for the proper air gap of the CKP sensor to the crankshaft reluctor ring. Often, they set the CKP sensor too far out away from the reluctor causing erratic readings or possibly no readings at all.

 

I have checked the power and ground at the sensor end along with manually turning the engine over while checking that the sensor is functioning properly by checking the voltage at the sensor. It went from 5V to 0V and back to 5V while performing this test. As far as the line going to the PCM, I didn't check that. Is there a location that shows the wiring of the sensor to the PCM? I was struggling yesterday as my Haynes Manual doesn't show this wiring.

The second thing you mentioned has me wondering. I do have an aftermarket timing cover on the engine. How would one determine if this was in case an issue? And is there any other fix other than putting a new cover on?

 

Swartlkk,

I have what is probably a stupid question, but this is the first time that I have done an engine swap so I am learning as I go. I stuck my finger in the crank sensor hole last night to feel around to find the reluctor ring to determine the amount of space between the sensor and ring. Problem is that I can't seem to find anything that feels like a ring in there. How many lobes would this ring have? 3 possibly? I bought a GM Remanufactured engine and I am wondering if I was supposed to re-use the old reluctor ring from the old engine. I know I didn't do this because I don't remember seeing it on the old engine and just assumed that the new engine would have what I need. So is the stupid question that I have, was I to re-use the reluctor ring from the old engine?

Thanks,

Hiney

 

I would assume that would depend on the engine. If you pull the CKP out you should be able to shine a light up there and see the ring. It is a gold ring that should sit almost in the middle of the hole for the sensor.

 

Thanks for the feedback myprixxx. I looked at it last night and there is no ring in there. The funny thing is that I don't remember seeing this on the old engine, but then again I wasn't looking for it either. That solves the mystery of why I am not getting a crank signal. It will just take a lot of time to get the ring back in there. Chalk one up to experience. I am sure I will never forget this one!

 

Just an update for everyone. I have installed the reluctor ring and then engine is all back in the vehicle. Cranked her over and she started within 10 seconds or so. Has been running well since. Looks like when you have what the sensor is looking for, the engine will run!