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Clayso, Master Automobile Technician
Category: Jeep
Satisfied Customers: 880
Experience:  ASE Master Certified Automobile Technician. 30 Years Experience.
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I have a 99 Jeep Grand Cherokee and it cranks but won't

Customer Question

I have a 99 Jeep Grand Cherokee and it cranks but won't start, when I took the camshaft sensor off it was broke inside. I can bump the engine and the rotor button turns so I know the oil pump drive assembly is not seized up. When I installed the new cam sensor and put new spark plugs in and put the coil pack back on it, it backfired and sounded like a canon going off and turned the ground behind the jeep black. I think the oil pump drive assembly has rotated a 1/4 turn because the plug is against the side of the engine block. There is no hole in the oil pump drive assembly to put a toothpick in to keep it lined up so I am not sure what to do now.
JA: Does the engine turn over? How old is the battery?
Customer: Battery is new, engine will crank but won't starting
JA: What year is your Grand Cherokee?
Customer: 1999 with a 4.0
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I have replaced the crankshaft position sensor, the cam sensor and spark plugs. I am thinking it is out of time but haven't checked that yet. I still think it has something to do with the oil pump drive assembly being rotated because it should plug in parallel to engine and mine plugs in against the block
JA: OK. To minimize me, please click the down arrow at the top right corner of this box. OK. To minimize me, please click the down arrow at the top right corner of this box. Anything else you think the mechanic should know?
Customer: Just that it backfired from the exhaust, I also know the oil pump is working
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Jeep Mechanic about your situation and then connect you two.
Submitted: 4 months ago.
Category: Jeep
Expert:  Clayso replied 4 months ago.

Hi There, I'm Clayso a certified master automobile technician with 30 years of automotive repair and diagnostic experience.

From your description sounds like you have the Camshaft Position (CMP) sensor out of time and sync. The link below is the correct way to install the oil pump drive.

Camshaft Position Sensor Service and Repair
If this service procedure doesn't match you application let me know your VIN.

With the oil pump drive removed the cam has no way to operate the oil pump. With the number 1 cylinder set at top dead center on the compression stroke install the oil pump drive with a toothpick through the shutter ring. Looking down into the engine with the oil pump drive removed you can see the oil pump. You will have to turn the oil pump with a long flat screwdriver to get it to line up with the oil pump drive. A professional level scan tool is required to set the sync for the CMP sensor, but with the CMP connector parallelled with the side of the block it should start and run without backfiring.

I hope this information is helpful. If you have any questions let me know. You can reply back to me through this thread at any time.

Kindly rate my assistance in a positive manner so I may have credit for helping you.
Positive ratings are greatly appreciated.

Expert:  Clayso replied 3 months ago.

Hi There,

I noticed you had viewed my answer, and I hope the information I gave was helpful. Let me know if you have followed through with my recommendations. If you have any questions, please let me know.

Positive ratings are greatly appreciated.
Thanks so much.

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