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Aaron

Aaron 11/26/2017

1991 Jeep Cherokee Laredo 6 Cyl 4.00L

Engine

cranks but wont start

I have replaced the Crank position sensor i have good spark i have good compresion i have good fuel pressure not sure what the issue is

5 Answers


Nick blignaut

Nick blignaut 11/27/2017

Have you scanned for any fault codes? If so and no codes present make sure you have 12vlots present at the sensor and battery voltage at least 12.40volts. Also get maf sensor cleaner and spray sensor and wait about 5min to dry before starting the car. Also did you do fuel pressure after the fuel filter if so have fuel filter replaced as it is a service item any way and won't do any harm by replacing it. Please keep me posted. Good luck!

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Aaron

Aaron 11/27/2017

I have fuel pressure at the rail i swapped the map sensor ans still no go and i think its an OBD 1 so i dont have the reader i goin to try ro borrow one. 12 volts at what sensor

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Nick blignaut

Nick blignaut 11/27/2017

I meant 12volts going to crank sensor but then you say you have good spark. Get the codes read and see from there. That MAF sensor you should clean it fits on air inlet pipe or air filter housing.

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Nick blignaut

Aaron 11/27/2017

I asked one of the mech. At work and he said the flexplate on these jeeps i how they get there timing for the ignition. So the outside lip has hole cut in it for the CPS. So the one i got from Autozone has the right bolt pattern but has a slot every 1/4 inch or so and the old one only has 6 holes in it so i need to replace the flexplate again

jdl

jdl 11/27/2017

Just curious, did you try using the mil on the dash to check trouble codes? You cycle the key on--off, on--off, on--off, on, then the mil on the dash starts flashing, you count the flashes to get the codes. Your looking for two digit codes.
Some older vehicles the mil no longer works, if it doesn't, that's a pain. On those vehicles, I use a scanner that shows live engine data, hopefully, I can find something that doesn't look right?

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Aaron

Aaron 11/27/2017

Well my problem all stemed from my flex plate, it started to crack so i ordered one from rockauto it was wrong didnt find that out till i had the tranny on the ground (crank bolt pattern was wrong) so i called Autozone they had one that matched the old flexplates bolt pattern but it had a whole bunch of hole cut and drilled in it didnt think anything of it at the time thought it was for balancing but turns out the 4.0L run its ignition timing off the flexplate so yeah timing is off and wont start new flexplate again yay lol fml

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