H3T Running out of Fuel with an 1/8th of a Tank Left

[RamRod]

BTW it is throwing no codes at all even when checked with a Tech II at the dealership

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[4speedfunk]

FP Relay? One time I got stranded in my Burb. So I jumped the relay terminals with a paper clip...started and ran great until I got a new relay.

You might also check the wiring for bite marks. Squirrels and chipmunks love GM wire insulation.

 

[RamRod]

Okay I just tried to check the Fuel pump relay.... but it turns out the H3T has a differnt Fuel Oump relay location then the rest of the h3's.....

On H3's its in location 66 on the fuse block.... if you read the sticker in the lide for the fuse panel it says slot 66 on the SUT (I assume this is the name they are using for the H3T) it says that it is a stop relay....

I thought well I don't have an SUT so this must not be for me.

I went to jump the connections to make sure that the relay is not the issue... and well turns out that the electrical engineers called the H3T a SUT and slot 66 is in fact the fuel pump relay.

Now my issue is trying to figure out where they put the damn fuel pump relay in the H3T's!!!!

I can't search for "Wiring Diagram H3T" because all that shows up is stuff for the H3

Anyone have any suggestions on how I can locate the hidden fuel pump relay???

Thanks!!!

 

[RamRod]

Oh and I have started to look for chewed wires, but found nothing suspect yet.

Fuel Pump Drive Module should be showing up tomorrow... so I will test that once I get home

 

[chaos254]

There is no separate fuel pump relay, it only has the fuel pump module. When it doesn't start, is it just cranking? What is the fuel pressure? Have you checked for power at the pump?

 

[RamRod]

Yes it is just cranking, I have to drop the tank to see if it's getting voltage.... but I don't think it is since there is zero pressure at the fuel rails

I won't be able to drop the tank until Tuesday at the soonest, and that's when the fuel pump module is coming...

So I will likely test the new modual out before dropping the tank again (to hook it up is a 30 second job).... but if that doesn't do the trick then I will drop the tank and check for voltage

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[chaos254]

well hopefully the new module fixes it but if not you should be able to check power to the pump at the module. That way you don't have to drop the tank.

 

[RamRod]

well hopefully the new module fixes it but if not you should be able to check power to the pump at the module. That way you don't have to drop the tank.

Right, good idea... i would have dropped the tank I find it strange that the wiring diagrams don't show the module.... yet i know its part of the system..

 

[Can007]

Have you replaced the fuel filter and/or the fuel pressure regulator?

 

[RamRod]

Have you replaced the fuel filter and/or the fuel pressure regulator?

The fuel filter was replaced with the new OEM fuel pump assembly.

Is there a fuel pressure regulator on the H3?

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[RamRod]

I finally got a code!

P069E - fuel pump control module requested mil illumination

Anyone have this one before?

 

[chaos254]

I finally got a code!

P069E - fuel pump control module requested mil illumination

Anyone have this one before?

EDIT: Just added a wiring diagram for the module/fuel pump

DTC P069E


DTC Descriptor
DTC P069E

• Fuel Pump Control Module Requested MIL Illumination

Circuit/System Description

The fuel pump flow control module uses the serial data network to signal the engine control module (ECM) that the fuel pump control module is requesting malfunction indicator lamp (MIL) illumination. This happens when the fuel pump control module has determines that a failure that affects emissions has occurred in fuel pump control system. When the ECM receives the message from the fuel pump control module, DTC P069E will set.

Conditions for Running the DTC

The ignition is ON, or the engine is running.

Conditions for Setting the DTC

The fuel pump control module requests the ECM to illuminate the MIL.

Action Taken When the DTC Sets

• DTC P069E is a Type A DTC.
• DTC P069E will continue to be correct or active as long as the fuel pump control module is requesting MIL illumination.

Conditions for Clearing the DTC

DTC P069E is a Type A DTC.

 

[RamRod]

Tried our the new Fuel Pump control Modual (FPCM) and no change... so I called up the local dealership and apparently the new FPCM does not need to be flashed (according the the dealership I just talked to)

So now I am going to dive into the wiring with a testlight and multimeter to see if I can find anything else....

But first I need to wait until Thursday for a buddy to winch me up my driveway (very steep) so I can dive into it all again

I am just about ready to tow it to a mechanic... one more go until Sunday then I give up

Between now and then any help would be appreciated!

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[Ghostbuster]

Good luck.

 

[Peep]

Yes good luck

 

[RamRod]

okay so I took a small motor bike 12v battery and hooked it up to the old fuel pump that I took out... fired right up seemed strong and confirms my believe that it was not the pump at all, it is some wire somewhere between the battery and the pump.

I went to use the volt meter on the harness tonight, but I am an idiot and left the meter on last time I used it so now I need to go pick up a new CR2032 battery in ther morning and then continue testing to find my issue

 

[RamRod]

EDIT: Just added a wiring diagram for the module/fuel pump

DTC P069E


DTC Descriptor
DTC P069E

• Fuel Pump Control Module Requested MIL Illumination

Circuit/System Description

The fuel pump flow control module uses the serial data network to signal the engine control module (ECM) that the fuel pump control module is requesting malfunction indicator lamp (MIL) illumination. This happens when the fuel pump control module has determines that a failure that affects emissions has occurred in fuel pump control system. When the ECM receives the message from the fuel pump control module, DTC P069E will set.

Conditions for Running the DTC

The ignition is ON, or the engine is running.

Conditions for Setting the DTC

The fuel pump control module requests the ECM to illuminate the MIL.

Action Taken When the DTC Sets

• DTC P069E is a Type A DTC.
• DTC P069E will continue to be correct or active as long as the fuel pump control module is requesting MIL illumination.

Conditions for Clearing the DTC

DTC P069E is a Type A DTC.



View attachment 22010

This is the exact diamgram i was going to look for tonight! thanks!!!

 

[Can007]

I have my fingers crossed!!!

 

[CaseyS]

Could possibly be the fuel pressure sender faulting and sending bad info to the module causing unpredictable pump speed commands. Have you checked the sensor?

 

[amrg]

Good luck

 

[RamRod]

Could possibly be the fuel pressure sender faulting and sending bad info to the module causing unpredictable pump speed commands. Have you checked the sensor?

Well the new assembly came with a new pressure sensor sending unit, but that doesn’t mean that not the issue, and I think it worth checking out, how do you check if its faulty?

I will be doing a full electrical sweep in about 2-3 hours from now, after I get some stuff done this AM

 

[RamRod]

okay the weirdest thing happened.

I walk out to the truck and try to start it. No start.

I think start with the fuses and check to see if they look fine visually but are somehow faulty by checking them the proper way with a multimeter.

I removed fuses #3 - Fuel Pump - its fine
#29 - off the run/crank relay- it's fine
#24 - - which was fine, but was not what i meant to check since i meant to check 54! (oops)
#54 - FSCM - It was fine as well

Then I put the key in the ignition, and I turned it to ON then went to pin #47 to check for a signal - Nothing - Which is what i expected since it took me longer then 2 seconds to get set up and i figured it is only programmed to say on for 2 seconds (read that some where) then stay off until the the vehicle is running.... as I was still there, with the Fuel Pump Control Modual unplugged trying to think of a way to get from the drivers seat to the back and check pin #47 before the 2 seconds were up

I HEARD THE FUEL PUMP KICK ON AND PRESSURIZE THE LINE!!!!!!

I don't know how this happened since I thought I had the wire that turns the fuel pump on unplugged (the whole Pigtail for the FPCM).....

So I plug the FPCM back in, walk up to the drivers side of the truck, crank it, and it starts!!

WFT???

am I reading the wiring diagram wrong?
Does this point towards a short somewhere?
Did touching pin 47 to a ground trigger something?
Did checking the fuses get one of the fuses back sitting as it should have been?

I am at a loss with explaining this, and until I figure it out I don't trust taking my truck out of the driveway because I don't know how long it will be before what ever it is gets triggered again and I am back to square one.

Please let me know your thoughts I am open to all ideas!!

 

[amrg]

**** electrical issues!!!!!

 

[RamRod]

**** electrical issues!!!!!

I agree!

now it wont start after I played around with the fuses some... I wanted to make sure that that wasn't the issue (corrosion)... strange thing is I don't read power to fuse #3 at all so that makes me think there is some issue up stream of the fuse since when I turn the ignition to on it should be sending power to fuse #3... shouldn't it?

 

[RamRod]

K so now that its not running again, I currently have no power at the fuel pump fuse, I do have power and ground to the FPCM but when the ignition is cycled there is a signal coming from the ECM to the FPCM but no signal to the fuel pump to turn on.

I am trying to think of sources that would not give us a signal:
-Faulty fuel pressure sensor (I feel this is unlikely due to the fact that the new fuel pump assembly came with a new sensor)
-problem between the FPCM and the Fuel pump connection (checking this now as it seems most suspect)

I have tried to use the new FPCM under various conditions and I don't believe the issue is stemming from the old one since it seems to make no difference