2015 Dodge Ram 1500 Starst but only Runs for Seconds

I have a 2015 Ram 1500 with 107,000km. The truck has never had a problem until now. I took my daughter who is learning to drive for short trip in a field. It was a little bumpy. Without turning the truck off, I then drove home several miles.

The next day, when I started the truck it will only run for two seconds. It then shuts off. Before towing the truck, I looked for any obvious issues with wiring disconnected, etc. I found nothing.

The vehicle was towed to a Dodge dealer. They have spent a total of eight hours attempting to diagnose the issue. They have been unable to do so.

I became concerned with the length of diagnostic time and spent some time visiting with their technician. It is a smaller dealership and appears to have only one technician.

He indicated he had tested every wiring connection point and nearly every wire in every harness running from the front to the back of the vehicle. He told me that he had found the fuel pump module was outputting only 7.6 volts to the fuel pump. While I watched he swapped that module for one from another working truck. It also gave the same 7.6 volts without the pump connected. He asked me if I thought it should be 12 volts or 7.6 volts. I suggested that he check the service manual for the proper voltage. He indicated that he wasn't aware of anywhere to find out what the voltage should be.

I asked what his computer was finding. But, he did not have it connected. He said he didn't see a point in looking at freezeframe data to see what the issue was.

I showed him how to manually power the fuel pump to prove it was indeed running. I also showed him how to short the ASD relay in an effort to see if something was forcing the truck off by ASD. He seemed unaware of either procedure.

I asked that he call the Chrysler helpline given the amount of time he had spent on the vehicle without a solution. He has declined to call support and now wants to change the fuel pump "incase it isn't getting enough power". He refused to connect a pressure meter to the service port to see what psi of fuel is being provided. Even if the 7.6 volts is an issue, its present without the pump connected so certainly doesn't make me suspect the pump is causing the low voltage. He measured the 7.6 volts by running a line to the battery negative terminal from his multimeter and connecting the positive side to the connector that would attach to the fuel pump and sender unit.

I've declined authorization for the pump and it is my intention to move the vehicle to a different dealership and start over. I don't feel starting to swap parts without first connecting the computer is a great idea.

The most obvious cause to me would be an immobilizer issue. I've tried both keys with the same result. There is no indication on the dash security light of a problem. There is no "check engine" light either.

The truck runs the same amount of time after it starts whether you idle, rev the engine or put it in gear and drive. It then stops the same way each time.

We've tried holding the key in the "start" position incase its a run position issue with the keyfob. However, the truck still stops and then simply restarts when the key is held there.

Has anyone seen a similar issue in such a new model ram 1500? I feel its the PCM shutting the truck down for some reason as opposed to an actual failed fuel pump / relay, etc. Even when I manually power the pump by providing power at the fuse box, the truck runs the same amount of time and stops.

Even if we assume I somehow damaged the fuel pump with a rough ride, the issue should have shown up immediately, not only the next day. In my mind if the pump is weak, the truck should idle fine but stall due to lack of fuel under a load condition. There was no warning of the issue and no symptoms of "getting worse" leading to this failure - it was simply instant.

At the moment we are $800 into the first dealerships failure to diagnose, plus a $500 towing fee to get the next dealership. Plus, the cost to diagnose and repair once there. Any suggestions from anyone who has seem something similar are more than welcome. I suspect its a rare but rather simple issue once you know whats causing it!

i agree with testing the fuel pressure. id check and see if its losing injector pulse. maybe try keeping it running with an alternate fuel source to rule out ignition. if it continues to run with the added fuel then we can focus on the fuel system alone, injector pulse

I also agree to check fuel pressure. When you bypassed the pump and it stalled do you remember if the pump was still running or did it stoo running as well? Theres a check valve that may have failed and maybe its allowing gas to leak back

I agree 100% with Cheryl and Nick
I assume your RAM has a gasoline engine rather than an oil burner.

You want to find out if you are losing fuel or ispark or both, if the engine continues running with propane introduced into the manifold then it points to a fuel system only problem. Putting a spark tester on a spark plug lead should tell you if the spark stops before engine comes to a dead stop.

I suspect the 7.6 volts at the fuel pump is actually 12.6 volts at about 60 % duty cycle using a digital meter with a duty cycle scale should confirm this .
Looking a fuel pressure with an old style gauge is a good move, If these engines have fuel pressure sensor it would be interesting to compare actual gauge pressure with the pressure on the data pid.

to add to the test you can unplug an injector if they are easy to get to. install a noid light and see if you have injection pulse while trying to keep it running on alternative fuel

Like andy said i dont know if this ram have a fuel pressure sensor but ford use this with a 5v reference and they said you have to check data pid with manual gauge to make sure your readings .also the sensor feeds back the computer to know how much pressure is in the system !

Whats the gas gauge show? Could be out of gas. Especially if there ends up being a fuel sender code. 7.6 volt reading is probably duty cycle like someone else mentioned. Would need a scope to be sure, or a data pid / functional test on a scan tool. Command pump at different %, then watch multimeter. I agree with you, I would be looking at immobilizer concerns, or some kind of circuit that's not used until after start up.

Have someone qualified look at it, or at the very least someone who can do a full code scan on vehicle and post the codes.