Fuel pump Relay

Hello,

The fuel pump relay and / or automatic shutdown (ASD) relay are in the fuse box under the hood. (DIAGRAM BELOW)

It is real common for General Motors pumps to quit and leave you sitting on the side of the road in a puddle of tears. Chrysler pumps almost never fail like that. They fail to start up when you try to start the engine but once they've started running, they don't quit while driving. If yours did, it's a much better bet there is an electrical problem with the wire going to it.

There is no manual reset switch. That was a very troublesome Ford item. Chrysler never used that silly design. The place to start is by bypassing the fuel pump relay to see if the pump runs. You don't even need the ignition switch to be turned on. As I recall, it is going to be the smaller relay on the right of my drawing. If you don't have a separate fuel pump relay, bypass the automatic shutdown relay, terminals 30 and 87.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

If it doesn't run on starting fluid, that proves there's more wrong than the fuel pump.

The fuel pump does have its own relay. It is turned on by the Engine Computer during engine rotation, (cranking or running). The computer turns the automatic shutdown (ASD) relay on at the same time. The ASD relay sends current to the injectors, coil pack, alternator field, and oxygen sensor heaters.

If you do have spark, we know the ASD relay is working. The only way the injectors could not have voltage on the dark green / orange feed wires is if there is a corroded splice or a cut wire. Can you double-check that voltage while a helper cranks the engine?

I know you don't have the 2.0L engine because that is a single cam engine. The 2.4L is not an interference engine so the valves won't be damaged if the timing belt jumps a few teeth or breaks, but the valves can hit each other if you turn the camshafts independently. If you do that and you feel binding or sudden excessive resistance, don't force them. The 2.5L has a single cam on each head. That is an interference engine. If the timing belt jumps three teeth or breaks, open valves will be hit by the pistons as they coast to a stop. You'll hear that by the way it cranks too fast and very smoothly.

If the timing belt jumps one tooth, the Check Engine light will be turned on and the fault code "cam and crank sync" will be set. If it jumps two teeth, the computer will stop the engine by turning off the ASD relay to protect the valves. On older models, signals had to be received by both the crankshaft position sensor and the camshaft position sensor for the computer to turn the ASD relay on. Beginning in the early 2000s on some models, the engine could still run if one sensor failed. Some would run on one failed sensor if you bypassed the ASD relay.

The next bit of confusion involves that fuel pressure you think you have. Besides the computer turning on the ASD and fuel pump relays during cranking, it also turns them on for one second when you turn on the ignition switch. That proves the pump, relay, and fuse are okay if you can hear the hum of the pump over the chime. That one-second burst is to insure fuel pressure is up high enough for engine starting in case it bled down over days or weeks. If the injectors are not firing, that fuel pressure should remain there. THAT is the pressure you could be measuring. That won't tell you if the pump is running during cranking. If you bypass the fuel pump relay, then hear the pump running or you hear the hiss coming from the fuel pressure regulator on the injector rail, we will know everything in that circuit is working.

If there are no fault codes, you'll need a scanner that displays live data to see what the Engine Computer sees. During cranking, the cam and crank sensors will be listed as "no" or "present" to indicate whether their signals are showing up at the computer. If both are listed as "no", the 5.0 volt feed wire or the ground wire, both common to both sensors, is open or grounded, or one of the sensors is shorted. If the wire or either sensor is shorted, the computer shuts the power supply down to protect it. Unplug the two sensors, turn the ignition switch off, then back on to reset the 5.0 volt power supply, then verify 5.0 volts is present in both connectors. Plug one sensor back in, then the second one. If the 5.0 volts goes away again when one sensor is plugged in, that one is shorted and must be replaced.

When the computer receives a sensor signal during cranking, it knows it should be getting a signal from the other one too, and when it doesn't, it sets the appropriate fault code. When both signals are missing, it assumes the engine isn't cranking properly and no code is likely to be set. That's where the scanner becomes necessary to see if one or both signals are missing.

The scanner will also show fuel as "off" or "allowed". If it is off, that can be the result of the anti-theft system. I won't go into detail there because I haven't had to work on many of them on Chrysler products, and that system would not cause the engine to stall while you were driving.

https://www.2carpros.com/articles/how-to-check-wiring

I have seen the harness for the cam sensor by the valve cover short together about 8-10 inches behind the connector. Check that as well.

Please let us know what happens.

Cheers, Ken

Have you checked for diagnostic fault codes?

How often were they switching? Every few minutes? Every few seconds? Was the engine up to normal temperature or did it start doing that while it was still cold?

First we need to clear up some stuff in my mind. In your first paragraph, nothing really said what the symptom was.

"... The car shut down and she couldn't restart it".

"After reaching her, I tried to start the car, but when I turned the key to the on position, I could not hear the fuel pump... "

"I tried to start the vehicle. Nothing."

"Nothing" is never descriptive. I don't know if nothing worked including dash lights, as though the battery was dead. There was no response from the starter but all the other electrical stuff worked. The starter cranked the engine slowly or normally but the engine didn't start and run. You get the idea.

You tested for voltage to the injectors, ignition coils, and fuel pump, but it sounds like you did that while the engine was running, or at least while the problem wasn't occurring. Of course those circuits will be working then, but now you know you're testing in the right places so you'll be ready when the problem acts up.

The relays are not the problem in this case. I never tested the resistance on one but if they specify 75 ohms, I'd be happy with 50 to 100 ohms. You're only measuring half of the relay, and that's the half that is least likely to fail. If the coil is shorted you'll find close to 0 ohms. That is extremely rare. If it's corroded open, it will read infinite. That's pretty uncommon too because if water gets inside, the contacts will typically corrode first. That's the other half of the relay that's harder to test. If you suspect a relay or just want to eliminate it as a possibility, just swap it with one of the other ones like it. It's not likely you'll have two bad ones at the same time.

As a point of interest, arced or pitted contacts on the relay can cause it to intermittently not switch on, or the contacts could intermittently arc and stick together, and not turn off, but they rarely fail once they are turned on and working. That COULD cause the fuel pump to not run for that first one second when you turn on the ignition switch, but it's very unlikely it would cause the sputtering and stalling while the engine was running.

As another point of interest, GM fuel pumps commonly fail while they're running, leaving you sitting on the side of the road in the middle of nowhere. Chrysler pumps, on the other hand, fail to start up when you start the engine, leaving you sitting in your driveway. They almost never fail once they've started up and you're driving. For that reason, I'm pretty sure the fuel pump is not the cause of the stalling. The one notable exception is if the pickup strainer gets plugged or collapses. The typical symptom is the engine will run fine at highway speed, but stall when the highest volume of fuel is pumped, which is during coasting, but you'll still hear the pump run for one second when you turn on the ignition switch. There could be an intermittent break in the wire going to the pump, but that wouldn't explain the other symptoms, (radiator fan).

Don't assume you're getting spark just because you found 12 volts at the ignition coil pack during cranking. You DO know the circuit responsible for 98 percent of no-starts is working if that voltage is there, but the coil pack could be bad. That's not too common either because there's two individual coils in it, and if one was defective, the engine would still run, but very poorly, on the other two cylinders.

So at this point we don't know if you're losing spark, fuel pressure, or both, and I don't know what "doesn't start" means, but if I had to offer a suggestion, given the erratic behavior of the radiator fan motor coupled with the lack of the fuel pump you heard at one point, I'm leaning toward an alternator problem. Young girls are notoriously inattentive to dash gauges and warning lights, and as long as the car is still moving, they won't notice the voltage dropping or the "battery" warning light is on. Low system voltage will make computers do weird things like cycle relays on and off repeatedly. There are other things that can cause the fuel pump to not run but those things won't affect the radiator fan.

On top of that, it is real common to have intermittent loss of output from the alternator due to worn brushes. I just replaced mine last summer at a cost of nine bucks. The brush assembly can be replaced on a lot of Chrysler models without even removing the alternator from the engine. With a good battery, the engine can still run okay for up to an hour or so, but then, once it stalls, the symptom will be no or slow cranking. Start by measuring the battery voltage with an inexpensive digital voltmeter. It must be 12.6 volts. If it is lower than 12.4 volts, charge it at a slow rate for an hour. If it's 12.2 volts, it's okay but discharged. If you find around 11 volts, it has a shorted cell and must be replaced.

Next, measure the voltage again with the engine running. It must be between 13.75 and 14.75 volts. If it stays the same as when the engine was off, we'll need to take voltage readings on the two smaller terminals on the back of the alternator.