Chrysler Repair: Fuel pump bad?, jeep grand cherokee, jeep vehicles

Question
I'm not sure if my fuel pump is bad. It cranks and after it gets hot it just stalls. Someone told me it might be the fuel pump regulator. Do you know anything about this? Or where it is located on a 1994 Jeep Grand CHerokee limited?

Thanks so much

Answer
Hi Anita,
I don't claim specific knowledge of Jeep vehicles as you probably noticed. But if they take after the Chrysler passenger line of cars then I would believe that the fuel pump or regulator is not a likely reason for stalling. The pump is in the fuel tank and you can listen for it to hum for about 1 second when you turn the ignition switch to the "run" position. It's voltage is cut off until you try the starter position, and once the engine is running you will have a hard time to determine whether it is running or not without getting your ear close to the tank, or by measuring the pressure in the fuel line which is controlled by the pump running and the pressure regulator in the fuel line near or on the engine.
A stall of an engine that has been running as it warms to operating temperature is more likely a temperature sensor that controls the mixture, or an electronic component that is failing due to its getting warmed up. The easiest way to find out what might be the cause is the ask the engine controller whether it has any fault codes stored in its memory. This can be done with a diagnostic readout box (and the autoparts stores such as Autozone will often do a readout for you for free). If that is not convenient you might try using the ignition key: in the Chrysler you turn it:"on-off-on-off-on and leave on" doing that in an elapsed time of 5 seconds or less. Then watch the check engine light which remains "on" to begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat to be sure the count is accurate. Then group the numbers in pairs in the order they appeared to form two digit numbers which are the fault codes. You can get the translation of these numbers at www.allpar.com/fix/codes.html
or write me back with the results. Once you have the codes and their meaning I should be able to tell you what to do.
But remember I am not really familiar with the specifics of the Jeep.
Roland