HELP!!! Fuel Pump Relay resets stalled engine...

[SURFSUP]

Short backstory. 2020 Jeep Gladiator RLE 65k miles. Have had a great dealer experience with multiple recalls, TSB's etc all being taken care of no questions asked. So my Jeep has been running great since September 2019 when I drove it off the lot with 15 miles on it. 50 by the time I was done test driving it.

Here is my issue. a couple months ago, the Jeep stalled running 50mph down a highway. Pulled over and wouldn't start. Would crank just fine but definitely not getting any fuel. Through some troubleshooting and engine codes, reading Fuel system short circuit, fuel system electrical issues. I unplugged the wire out of the back of the fuel pump and plugged it back in and it fired right up. Thinking maybe a dirty connector and that was it we carried on.

A month later it left me stranded for 30 minutes at a car wash. Did the same trick and it wouldn't run, same issues, same engine DTC codes. After sitting there for about 30 minutes it started and ran fine.

A week later in front of my wifes Salon, it did the same thing. I didn't have time to deal with it so the wife gave me a ride home so I could grab my other vehicle and carry on about my day. Came back a few hours later fingers crossed it would start and sure enough fired right up and drove it home.

Last weekend while on a road trip to a volleyball tournament for our middle daughter, it died at the gas station after I just filled it up. Left us stranded for 4 hours until and this is where it gets fun, I swapped the Fuel Relay in the fuse box with the relay for AUX switch #4, went to drivers side, pushed the brake with my left hand and pushed the start/run button, fired right up. Ok so I am thinking faulty relay. Didn't have time to deal with this as it was midnight with 2.5 hours more driving to get to location of the tourney. Pulled in at 2:30am, slept four hours and went to leave to the tourney location from hotel. Took dog out for potty while wife was finishing getting ready and thought, lets make sure it starts. Fired right up. Thinking definitely bad relay. Wife comes out and we start the jeep to no running, just the starter turning the motor just as before. Perplexed I hop out, pull the relay, double check it plug it back in and it turns over just fine. Now I am super confused.

We are now at the point a week later where I can almost guarantee after a couple of starts it will fail. I hop out, pull the relay, reseat it or sometimes swap with AUX#4 relay, and the jeep starts.

After all this, the soonest I can get in the dealer mind you I booked this two weeks ago after the fourth time it did this I was in for an oil change, is May 22.

My best guess is its the fuel pump that gets reset after I pull the relay and it looses all power and then fires up fine for a few starts? Any other thoughts or suggestions before I drop this off at the dealership? Obviously out of warranty so before I drop $500 on a new fuel pump and the labor to install as I feel thats what the dealership will do as well. Is it worth trying a new relay first?

Btw in the last week this has stalled out 10+ times now each time pulling the relay or swapping with the aux#4 relay it fires right up. I don't believe it to be a relay as I can move the relay from AUX#4 to fuel pump location and back and fourth and both will work fine, the aux 4 is wired up to some lights I have and they never fail.

Open to suggestions and dialogue. Please help??

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[Mr._Bill]

A new relay is something you should have already done. I don't think that is the problem, but you won't know until you try it. Check the wiring harness to the fuel pump for any damage.

 

[SURFSUP]

A new relay is something you should have already done. I don't think that is the problem, but you won't know until you try it. Check the wiring harness to the fuel pump for any damage.

Thanks Mr. Bill. I don’t think it’s relay either and I have inspected the wiring harness at the fuel pump as well. Mother I can see is damaged or crimped. Bone dry up there as well so I don’t believe it to be water damage.

 

[Darkamek]

Relays go bad with arcing across the contacts. The only way to check that would be to put 12v across the coil and ohm out the contacts.

The other option would be to put an oscilloscope on the fuel pump motor to see how it is acting.

Other than that you would need to verify voltage at the harness to the fuel pump. Making sure that no critters or anything damaged the wiring.

 

[SURFSUP]

Relays go bad with arcing across the contacts. The only way to check that would be to put 12v across the coil and ohm out the contacts.

The other option would be to put an oscilloscope on the fuel pump motor to see how it is acting.

Other than that you would need to verify voltage at the harness to the fuel pump. Making sure that no critters or anything damaged the wiring.

THank you for the tips. As I mentioned before, I have swapped the AUX#4 relay to the same outcome of stalling and that relay runs my Rigid Ditch lights at the bottom of the A-Pillars at the windshield and cowl. No issues there as well as when swapping the fuel pump relay to the aux#4 location the lights continued to work for hours while driving last weekend late at night.

Critters are definitely a possibility. I am not well versed in the voltages and testing procedures for a fuel pump so I may rely on my other two tools in my tool box, a pen and a checkbook. Don't get me wrong I am a Software Engineer and DBA and love to figure things out on my own but sometimes my time is more valuable to me and maybe this will be one of those times. If I can take a voltmeter to the wiring harness to the fuel pump and with a proper pin read out for testing what I should see I could feel confident in doing so. I just don't know enough about it.

My logic says that the pump is bad by pulling the relay and disallowing any voltage to the pump it will and this is my terminology "relax" or unprime the pump. Maybe it has something it keeps trying to suck up in the tank and this lets it fall down and out of the pump.

Am I correct in the fuel filter is inside of the pump? My thinking is the fuel pump primes and then gets clogged and there is no pressure to the fuel rail and it just turns over without starting?

 

[Varooom]

Mine never stalled, but 2 out of 5 times it won't start. It cranks but just spins. I stop it and try again, it always starts the second time.
Took it to the dealer, said the fuel pump is "bleeding down" and has to be replaced. Now I wait for a new pump, about 2 weeks. You could have a bad pump.
Varooom

 

[SURFSUP]

Well, I think we have found the culprit and it would make sense as to why unplugging and plugging in the relay especially the fuel pump relay would cause a fix to the issue not 100% of the time but most of the time.

A few months back, I pulled the aux battery as it had failed and was draining my main battery and subsequently killed my main battery. So I purchased a High end Main battery and opted to do the aux battery delete. For anyone who is familiar with this you know you have to either go in through the wheel well or from above through the power distribution box. What I have learned is in my putting it all back together the four posts that screw the power distribution and relay connections to the cables below was not torqued down properly, and subsequently the power plugs from below. The distribution block had become slightly disconnected. So as I would push the relay down, it would then receipt the distribution block into those large cable connections.

So far, we are on a full day of multiple at least a dozen plus starts and not one issue. Fingers crossed that this is my fix.

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