ra.stewart

Been searching on this, but have a question. My 2001 started stalling the other day, exhibiting the same symptoms as my old 96 Cherokee and old S-10 did that turned out to be a bad fuel pump. I understand that a failing CPS will shut the fuel pump down, but when it does, does it also shut down anything else? I get no CEL or indication on the dash that anything is up as it dies. It just stalls at a light or looses power in motion, the tach doesn't react like the ignition is off. At 122K miles I suspect the fuel pump on any vehicle and it seems this is more of a problem if the tank is low(of course since the first time this happened I have been putting in $5 worth so I don't have to drain 15 gallons of gas!). Any input on this? Should I just buy a pump and a CPS and move on? Thanks in advance!

CCKen

Check the fuel pressure at the fuel rail. You should get 49.2 psi +/- .5 psi.


Rent a fuel pressure test set at your local auto parts store and attach it to the test port on the fuel rail. First, turn the ignition switch to ON/RUN (without cranking the engine) and see what the gauge reads. Next, start the engine and check the gauge.


If the pressure is too low you may want to replace the fuel pump module (Bosch or Carter). If it's okay then suspect another sensor.


A failing CPS will shut down the fuel pump and the ASD relay.

Deltatech

I know this an old thread but is this condition specific to the 96 or would the same be true for all years? I'm tracking a no spark condition and trying to rule out either the CPS or The Stator/distributor pickup on a 4.0 92 and didn't want to start a new thread.

BloNdeChiNeEz

I changed out my fuel pump on my 93 zj and it still stalled out. Then after asking around, I was told to change the crankshaft position sensor. No more stalling! Make sure to check if your ckps is either bolted in by a 1 bolt or 2 bolt. Mine was a 2 bolt. I don't know what years the different bolts are used though, but check yours before buying a new one.

BlueRidgeMark

97grand4.0

A two bolt crank sensor on a Grand Cherokee?? I don beleve it

BloNdeChiNeEz

if we are talking about cpks, believe it. My 93 zj crankshaft position sensor is bolted on by TWO 2 bolts. If I had saved the old one, I'd post a pic.

97grand4.0

Ah, ok Bonde. Well maybe you have a different transmission from my 42RE. ?

Dave51

Rob Foster

OK. Need help. Working on 96 4.0 and replaced ignition switch and cylinder. The unit wouldn't start before I replaced but had to unrig some bad repairs from prior mechanic. I have power to all relays in compartment but no power to coil and possibly fuel pump (not confirmed with volt meter). All fuses are good and I seem to not have power to DK GRN/ORG to coil and DK GRN/WHT fuel pump. The vehicle was running just prior to this. Got talked into helping a family member.... (never again) Is the CPS the next logical step? I haven't jumped out the relays as of yet to see if I can bypass whatever is not making contact. It really has to be something easy that I just haven't found. Any advise would be appreciated.