Fuel pump not working

Unless you are cranking the engine while checking for twelve volts, there had better be zero volts to the fuel pump. What problem are you trying to solve? Have you checked for spark? Do you have access to a a scanner?

If the fuel pump would run with just the ignition switch turned on, that would pose a serious fire hazard if a fuel line got ruptured in a crash. For that reason, no electric fuel pump on any car brand runs all the time. Some pumps on older cars could be turned on by a tap on the oil pressure switch, but most, including all Chrysler pumps, have a fuel pump relay that turns on when the engine computer sees the crankshaft is rotating, (cranking or running). It knows that by the signal pulses it receives from the crankshaft position sensor and the camshaft position sensor.

All Chrysler fuel pumps will run for one second when the ignition switch is turned on in addition to when the crankshaft is rotating. If you can hear the hum of the pump for that one second, that proves the fuel pump, relay, and all its related circuitry are okay, and the computer has control over it.

To back up for a minute, when the ignition switch is turned on, the engine computer turns on the automatic shutdown, (ASD) relay for one second. That relay sends twelve volts to the ignition coil(s), injectors, oxygen sensor heaters, alternator field, and the fuel pump or a separate fuel pump relay. On a few models the fuel pump relay and ASD relay are on separate circuits but the computer still turns them on and off at the same time.

When you have a scanner, you can watch the live data screen to see if the one or two relays switch from "off" to "on" but that can be tricky because that occurs when you turn the ignition switch on. Since it was just off, the scanner will not be active yet. By the time it goes back to displaying the data screen, the relays have turned off again. What you still can do though is watch to see if they turn on during cranking.

When you do not have a scanner, use a test light to see if and when the ASD relay turns on. Look for the wire that is the same color at every injector and at the ignition coil. Most commonly that is a dark green/orange wire. You can also use either smaller terminal on the back of the alternator. Back-probe through the rubber weather-pack seal. Never strip a wire to take a reading. You can use a voltmeter too, but those do not respond fast enough and are harder to see. You should see the test light turn on for one second when you turn on the ignition switch, then it will turn off. What is important is the light should turn on again during cranking. If it does not, the cam and crank sensors are suspect.

On Chrysler vehicles, no spark accounts for about two percent of crank/no-starts. No fuel pressure accounts for perhaps three percent. For those, the individual circuit must be diagnosed. By far it is more common to find no spark and no fuel pressure. That occurs about ninety five percent of the time, and is not related to either circuit. That is caused by what they have in common which is the ASD relay and the two sensors. This is why I asked if you have spark. Way too many people find the first thing that is missing and they get stuck on that without looking for the additional symptoms and clues.

If you do find the ASD relay does not turn back on during cranking, you really do need a scanner to see what the two sensors are doing. I have a Chrysler DRB3 for all of my vehicles that lists each sensor with a "no" or "present" during cranking. A lot of independent shops bought these scanners because with an extra plug-in card, they will do emissions-related stuff on all brands of 1996 and newer vehicles. These became obsolete by 2008 and no longer worked on a few 2004 models. For that reason, you might find one at a local shop that would like to sell it so they can invest in something newer. You can find them on eBay too. There are plenty of other aftermarket scanners but I am not familiar with how they display the state of these sensors.

If the ASD relay does turn on solidly during cranking, the two sensors are okay. You should have spark too. Then we will have to see if the fuel pump is running when a helper cranks the engine. That is the time to check for twelve volts there. We will need to look at the ground wire too.