93 JGC fuel issues

[Doug06512]

I have a 93 jgc w/ a 4.o
replaced the fuel pump about 6 mnths ago.
latley I have had a hard time strating the jeep.
what happens is when I turn the ignition key the engine just turns over w/out starting.then after a number of cranks it starts.
what I did notice is when the check engine light goes on it starts and I can hear the fuel pump.when the check engine light is off it wont start.
I have not been able to see if I am getting power to the pump yet.
I am thinking I might have a short somewhere?
thanks

[dksob81]

CPS!

Your CrankShaft Position sensor is bad, this is the most common cause of this.

it could also be the PCM but most likely and most common is the CPS.

Remeber to disconnect the battery before removing/replacing any electrical component.......

[Doug06512]

I don't' know I will try it.
The reason I dont think its the cps is once it is running it runs fine.
wouldn't it run rough or stall if it's the cps?
thanks

[dksob81]

rough running and stalling is soem other symptoms of a bad CPS, but the NO CHECK ENGINE light is another cause. I am sure if you search it you will see.

[Doug06512]

well I replaced the CPS and still no luck.
now I can't even get the codes to flash w/ the key switch.

[dksob81]

so you are not getting a CHECK ENGINE light at all, now?

did you disconnect the battery before replacing the CPS? You must disconnect the battery before replacing any electrical component replacement.

Also, what brand was the CPS? BORG WARNER brand are known to be bad 'OUT OF THE BOX'.

[Doug06512]

I am "NOT" getting a check engine light at all.
yes the battery was taken out to charge
Wells was the brand and I tried (2) thinking the first was bad.

I have not been able to check for spark yet,I had spark before so I am
assuming I still have spark.I am also thinking it might be the computer box located on the fender well.
thanks
Doug

[dksob81]

Well if you replaced the CPS twice and remembered to disconnect the battery and you still have no CHECK ENGINE light, then the only other thing would be the ocmputer located on the passengerside Firewall behind the coolant reserve bottle.

[Doug06512]

Thanks for all your help
I fixed the jeep w/ a new computer.

My take is that if you do NOT have a check engine light
it is most likley the computer.

[ZJenvy242]

That should be made into a law. "If you trun the key and you hear clicking noises anywhere between 30 seconds to 30 minutes and its the fuel pump. Then you must repalce you PCM(computer). I went through 2 months or diagnostics and replacong sensors and the fuel pump before the idea clicked in my head of changing the Jeep's brain, It's been running solid for well over a year with a $200 used computer and 10 minutes of wrench (screwdriver actually) time.