Thank you, I really appreciate that information. I replaced the CPS yesterday with a BWD brand sensor as the stealership states the one I need (with rectangular connector) is on national backorder. No joy. I don't have a fuel pressure tester so I am doing the next best thing. There is a local mechanic that I have used for over ten years, referred many people to, have never heard a complaint or problem from or about, that now has the Jeepster to figure out if it is the fuel pump. I also sent the old CPS in the event the new one is bad. At my age, carport for a working area, I really didn't want to crawl under the Jeepster and try the fuel pump replacement. So I will tend to my garden today and drink a beer. Thanks again!

 

OK..this is enough to make a sane person crazy. Had my Jeep flatbeded to the mechanic shop last night. The only material thing I did to it was to change the OEM CPS out with a BWD Brand CPS and it did not start. The mechanic went to it this am and it started right up. Can this be a failing fuel pump? They are checking all the wiring for frayed or burnt, but the vehicle has not blown any fuses ever. Anything I should tell them specifically to check?

 

So the mechanic drove the Jeep today. About a 4 mile test drive. Then it would not start again, just turn over...

 

TEST the CPS.

 

your welcome

 

CPS tested good both in volts and resistance.

 

Right when it failed, or later?

 

Unless the landscape has changed, there is not a voltage check we do for 91-02 Jeep CPS's,* only the 87-90 Renix. Actually I gather, with a $300 Fluke meter, or an oscilloscope, it's doable though.
(*other than a 5V PCM feed maybe)

Bruce, I'm guessing Cruiser was pointing out, a guy might want to do that resistance test right then and there, after it quit. Later cooled off it might work again.

 

!^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^! You can hear it for maybe two seconds, after turning the key on. If not, it's not running right there, that's a real problem. (no start) It will start running again after the CPS sends a signal to the PCM that it's running, then the PCM will ground the fuel pump relay to run it. (Or the ADD OR ADS 0r ARS rO the ASD, or some relay.

Like DJB said, if it's sat a bit and you turn the key to IGN on, you should hear the pump in the tank hum for at least a second.

 

Fuel pump is working and pressure is within spec. Replaced CPS with BWD brand aftermarket. Jeep will run fine, start right up. Drive around, make multiple stops. Engine off for periods of 10 minutes to a couple of hours and overnight. Then it just chooses not to start, just turn over. Later it will start again. We have removed the hood and hooked up a inline spark tester and a fuel pressure gauge in a way we can drive the Jeep around to better figure out what stops working when it won't start. We also replaced the inline fuel filter and filled the gas tank with fresh gas, 17 gallons.
The mechanic also poured in a can of dry gas just to be sure. So we shall see what is causing the ghost in the machine hopefully. It is 40 degrees this am and I have to ride a motorcycle to work. Beats walking though...

 

Been a week now, the new CPS has seemed to identified the starting problem. Thank you all for your input.