Fuel pump shut off

FISHDODGE

MEMBER
2000 DODGE TRUCK
5.9L
V8
4WD
AUTOMATIC
218,000 MILES

Truck starts first time every time intermittently the vehicle will shutdown. There is no power to the fuel pump when it has sat and cooled off truck fires back up and runs fine until next shutdown. I have replaced the fuel pump and relay. I believe there is something shutting off power at the ASD, but I don’t know what is coming into the relay. As a side note I have shot gas into the intake during the shutdown period and it will start up. Any ideas? Thanks

Saturday, June 22nd, 2019 AT 8:18 AM

6 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Hi FishDodge,

If the vehicle starts when this happening by just adding a fuel source then it is not the ASD. The ASD not only controls the injectors but it controls the ignition coils as well. Also, if the ASD shuts down the engine, it will set a code so we can confirm this by checking codes.

If this is just low pressure or no fuel, then I will guess you don't have any codes. However, let's go ahead and check for any codes just to be sure.

If there are no codes, then we need to hook up a fuel pressure gauge and find out what the pressure is when this is happening.

When you replaced the fuel pump, did that come with a regulator as well? I am thinking you have an issue with the regulator is it was not part of the pump. It sits on top of the pump and can be serviced separate.

Let me know if there are codes and if you put a new regulator on with the pump. Then get a PSI at the rail when this is happening, and I am sure we can figure this out. Thanks

Images (Click to make bigger)

Was this

answer

helpful?

Yes

Saturday, June 22nd, 2019 AT 9:29 AM

FISHDODGE

MEMBER
4 POSTS

I replaced the pump as a package that came with new regulator. No codes show up and I checked the PSI it is in the fifty’s. I am currently replacing the crank position sensor. I have a neighbor who races cars and does his own work. That this is a long shot but could be the problem. Thanks for the help. I will get the part and install tomorrow.

Was this

answer

helpful?

Yes

Saturday, June 22nd, 2019 AT 4:15 PM

FISHDODGE

MEMBER
4 POSTS

No luck with the crank position-er sensor still starts and runs until it gets warm then shuts down. Any idea where to go next?

Was this

answer

helpful?

Yes

Sunday, June 23rd, 2019 AT 2:27 PM

KASEKENNY

MECHANIC
18,907 POSTS

So next steps need to be to see what you don't have between fuel pressure and spark when this is acting up. So hooking a fuel pressure gauge up and seeing what pressure is when it is cranking. However, I assume it is spark related due to everything you replaced with fuel. So when this is acting up, remove a plug and hook the wire up to it and hold it against the engine block and crank the engine. You should see a strong spark. I suspect you won't then we can start chasing why you have no spark with it gets warm.

FYI - if this is all true, I am thinking PCM is the issue.

Was this

answer

helpful?

Yes

Tuesday, June 25th, 2019 AT 5:35 PM

FISHDODGE

MEMBER
4 POSTS

Okay, the guy that races brought his OBD ll over and hooked it up and discovered that there is no communication between it and the vehicle (I have a very cheap reader that is apparently not working). Also I was incorrect in my analysis that only the fuel pump lost power during a shutdown there is also no spark to the plugs, we used the method you described when the vehicle cools down the spark returns is there any way to analyze the PCM for a fault.

Was this

answer

helpful?

Yes

Tuesday, June 25th, 2019 AT 7:36 PM

KASEKENNY

MECHANIC
18,907 POSTS

Unfortunately, I think the PCM holds the key to figuring out what the issue is because I suspect there is a code or at the very least we can see why the PCM is shutting down the ASD.

There may be an issue in the PDC as well. What I would suggest is to start with measuring voltage from the PDC to the ASD relay. If there is no voltage when this is happening then the PDC is the problem.

As for not communicating with the scan tool, you will need to follow the second wiring diagram and see what connection is open. The only way you don't have communication is if the DLC and PCM are not connected by the 4 wires shown. I suspect you have an issue with the joint connector shown.

Let me know what you find and we can go from there.

Images (Click to make bigger)