07 nbs 4.8 - sputtered on throttle for a week, now dead

[LAYNLOW]

This is my first post and I'm new here. I have a '07 ext cab Silverado, 4.8, 96,000 miles, non-flex fuel, LT, 2WD, 3.23 rear, in Tennessee.

The problem started one day when I left a traffic light. I took off and when it reached around 10 mph, it dumped out and then picked back up as if it was out of gas, which I thought it was. It was very low on fuel. I stopped and got some gas but the problem persisted and got worse. I thought I had let the fuel level get low enough to pick up some trash from the bottom of the tank. I've done this before and it clogged up the fuel filter. But, alas, there is no serviceable fuel filter on this truck.

I continued driving it with the sputtering/dumping/hesitation/whatever you call it. It feels like you hit the throttle and then once it starts going you've turned the key off. But it picks back up. I finally got a "check engine" light so I pulled the 3 DTC's, which were all fuel pump related, one being the fuel pump relay, which I changed. Cleared the codes, they came back with a vengeance, so I exposed the fuel tank from the top. Back in the day, I could pull the bed off a Silverado with one other person and set it on the ground. This truck has a heavy bed, plus I had no immediate help, so I devised a slick way to slide the bed back three feet by using a couple of 4 ft 4x4 posts and two pieces of 6 ft. conduit, but that's for another post, I guess. Anyway, I pulled the pump, set the pick up in a can of gasoline and wired it straight to the battery. It made way more noise than I thought it would make, plus it barely trickled gasoline out the supply. So I disassembled the rack and cleaned everything to where it all looked like new and tried the straight wire thing again. Same result, so I ordered a new Delphi fuel pump assembly and waited three days for it to show. Hey, $256 vs. $526 at my local dealer is worth a three day wait to me. In the meantime I dropped the spare tire and pulled the plug and cleaned all the terminals of the harness junction and verified a good ground.

Got the new pump and installed it. The truck cranked right up and throttled up just as it should, so I put the whole thing back together and went for a test drive. It did the dump out thing almost immediately but not nearly as bad. Also, it doesn't just buck once. It felt like you were trying to break a horse, as if someone was driving and going from no throttle to wide open throttle and back again. If you barely used any throttle at all, it would almost act normally so I knew the problem was in the fuel delivery. However, within ten minutes the engine had sputtered to the point that I barely got it back in to my driveway. Now it will not crank. Fuse, relay and fuel pump have been changed. Ground and wiring are good, but I'm about to put it on jack stands and recheck the ground because I have a funny feeling about it.

Any help would be greatly appreciated. I rebuild muscle cars from frame off and everything in between so I'm the guy that has never taken a car to a dealer or a repair shop for anything. My day job is as a Network Engineer so I was one of the few that welcomed the auto computer age so that doesn't scare me either. I will say, though, that this truck requires some searching if you're looking for something like a relay.

Thanks in advance for any help.

[michigan2500hd]

Wondering if it has to do with the drive by wire throttle?..just a guess really but I had one go bad on my 05 1500

[LAYNLOW]

I started to discount the throttle control but I can't think of a reason to rule it out. I'll check first thing in the morning. Thanks.

I'm finding some odd behavior between the fuel supply module and the pump. There's power to the module at all times and

that ground is good. I checked the wires leading from the module to the pump and the positive (gray) had continuity to ground,

as well as the ground wire (pink), yet when I turned the key on the positive lost the ground continuity but didn't show power

to it. In my experience this is usually a poor ground but I haven't been able to locate a bad ground. I straight wired power to the

pink and gray but the pump never turned on, which led me to believe there was a break or short in the run from the module to

the pump so I pulled the plug at the pump but I had good continuity on both pink and gray. I must be too tired to think. Possibly,

there's a problem at the plug on the pump end. I still have the old pump, which works but is weak. Tomorrow I will straight wire power

and ground to the pink and gray at the module with it unplugged from the module and connect the old pump to make sure that wire

run is good and that the plug is good. Hopefully I'll get some answers from that. The fact that I wasn't able to see any power being

fed from the fuel control module leads me to believe the module is bad but I'm having trouble believing that. Those things just don't

go bad very often, but if the module to pump wire run and it's plug check out, I have to believe the module is bad. Does anyone know

how to troubleshoot the fuel control module besides a lack of power on the output? Normally I would say that alone indicates module

failure but in this case with all the other questionable issues, I'd like to have a second module test to be definitive before I go spend

another $100. I was never one to troubleshoot by replacing parts, very much unlike most dealerships seem to be from what I've been

told.

Thanks for the responses.

[CapitalTruck]

Any luck with this?

[LAYNLOW]

No luck. Throttle by wire can't be the issue because the thing won't run at all. I checked the fuel control module, above the spare tire, and found that it wasn't sending power to the pump so I replaced it. Still nothing. I tested the wires on the module but I don't really know what I'm looking for. The new module is not sending power to the pump either. But when I turn the key on, one of the leads going in the module is carrying 12 volts, with the rest at either 0 or 1.02 volts. Still no power on the large gray going to the pump. On the plug for the module there is a full time 12 volt pos and neg going in. At the opposite end of the plug are the gray and pink, pos and neg going to the pump. I checked ohms on those wires and they are good. I can even jumper across the plug and make the pump run, which I've only done for a couple of seconds at a time. When I do this the engine will crank and run for a couple of seconds until it burns what little fuel I sent it. I've been lying under the truck checking the fuel supply module plug all morning.

I'm completely stumped on this. If one of the small leads wasn't sending 12 volts to the supply module when I turned on the key, I'd think the problem was up front, but it appears the signal is being sent to turn the module on. I'm wondering about security. I'm going to my wife's workplace to grab her key to my truck and try that. I'm lost at the moment. When I bought the fuel supply module at the dealership I asked if it required programming and the parts guy consulted with a mechanic and came back with "no, it shouldn't need programming" to which I replied "what the hell do you mean by "shouldn't"" and he said "no, it does not need programming" but he didn't say it with a lot of conviction. I've seen another post where someone claimed that the module had to be programmed but I disassembled the old one and I can't see that it has any write over chips on the board.

HELP!!

[LAYNLOW]

Not a security issue, either. I'm stumped.

[AirForceAngler]

Possibly a problem with the fuel pressure regulator? Just guessing here now.

[LAYNLOW]

There is no fuel pressure regulator. There is a fuel pressure sensor on the fuel pump rack that feeds information back to the fuel supply module.

I can't even think about testing that until the pressure is up after the pump has been running. The neutral state is open, which allows the supply

module to feed power to the pump. That sensor is new, which came in the new fuel pump rack.

[CapitalTruck]

alldatadiy.com has wiring diagrams. Isn't there a fuel pump relay under the hood? I know you're getting 12 volts back, does that in your mind eliminate the relays as being a possibility? I can see how it would (it kind of does for me). Having said that maybe one of the other prongs should be sending power back there and it isn't? See if you can find a relay test procedure and check those out under the hood. Just a possibility.

[LAYNLOW]

Okay, will do. Yeah, I eliminated the fuse and relay because the wires run directly from the supply module to the pump. The relay and fuse are both before the

supply module. If there's a pressure regulator, that's news to me and I certainly apologize for the presumption.

I'll troubleshoot more and post my results.

Thanks to all that are chiming in on this.

[AirForceAngler]

What other codes are you getting from the computer? In addition to the fuel pressure regulator, I'd also take a look at the throttle position sensor. Maybe if the TPS is bad or going bad, it is sending bad signals to the computer that is then causing the injectors to pulse. Get the codes and do a Google search for them and your model truck. Seems to me that you're wearing out your multimeter needlessly. Generally, researching the codes can get you in the ballpark pretty quickly. Good luck!

[LAYNLOW]

Did the code research and all three led to the fuel pump. I did find a skinned wire that was shorting today on the left front near the suspension. After I repaired that, I now can crank it and it will run for two seconds and quit. Then it will try to crank as if it's out of gas but never run. If I turn the key off for a minute or so it will do the two second run thing again. I'm interested in the throttle position sensor. That sounds like a possibility. I'll update once I check that.

[CapitalTruck]

is there a shraeder valve on these engines that would allow you to confirm/disconfirm fuel delivery? I know most of the fords had them.

[brainpause]

Did the code research and all three led to the fuel pump. I did find a skinned wire that was shorting today on the left front near the suspension. After I repaired that, I now can crank it and it will run for two seconds and quit. Then it will try to crank as if it's out of gas but never run. If I turn the key off for a minute or so it will do the two second run thing again. I'm interested in the throttle position sensor. That sounds like a possibility. I'll update once I check that.

 

 

Did you try turning the key to ON (but not START), allowing the fuel pump to build pressure, before starting? Don't have to do this routinely, but after changing many of the fuel system items, maybe they've bled down and just need to be filled/pressurized with fuel.

 

Larry

[LAYNLOW]

DTC codes are:

 

P0230

P069E

U0109

 

If anyone has further insight in relation to the DTCs, it would be very much appreciated. Again, I've replaced the fuel pump rack as well as the

fuel supply module. I can't shake the feeling that I have a ground issue going on here even though I've checked all the grounds in the vicinity.

Thanks for all the suggestions and help.