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2007 gmc sierra ltz 5.3 died while driving


gmc70

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hey guys, great site

 

I was driving home tonight with my sons 14-6 & 8 weeks, when all of the sudden I noticed my gas pedal went soft I looked down and there's no rpms so I throw in in neutral and try to start it but it wont start so I pull over and put it in park and try again, but it wont start it just turns over, I sat there and tried a few more times but no luck, so I pop the hood and check everything over and don't see anything out of place so I let it sit for a few and try again but still just turns over, So I called my father in law and we towed it home, it has gas and oil it wasn't hot, I have no Idea what it could be, the truck is a 2007 GMC sierra slt with the 5.3 engine,

 

Any ideas what it could be? fuel pump?

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I would have checked the fuel pump control module. Bud who works for gm dealer says they like to go out at 100k or so. Gives symptoms of bad pump but the module controls the pump. Took mine out and had standing water in it. A lot easier to check that then the pump

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It appears to be. Has to be one of the dumbest ideas ever. I could understand if external filters never plugged up, but we all know they do plug up.

 

Check for fuel flow as close to the tank as possible, if the pump is making noise, you are left with needing to verify fuel flow.

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I could be wrong, but the pump could be getting power from another source and the control module tells the pump how much to send and at what PSI... just a thought.... As a sys admin I tend to eliminate all the silly things before i touch the big items... if replacing a network cable can/would have fixed it why replace the switch?

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Borrowed a tester from AZ and hooked it up turned the truck over and no pressure.

 

So its the fuel pump.

 

Or the relay, or the fuse, or one of the safety relays, or broken wire, or.....

 

A pump may indeed fix it, but you are rolling the dice. Check for power at the pump first, and also check the ground at the pump. Remember that you likely cannot return the pump if it turns out to be a fuse.

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Well since there is power to the pump I figured the control module was good. I checked everything else.

 

 

Now that I have the fuel pump, tonight I had to drop the tank because the damn fuel line wont come off the pump even with a tool I bought at Oreillys the connector wont budge, dropping the tank was a breeze no weight to it at all.

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Or the relay, or the fuse, or one of the safety relays, or broken wire, or.....

 

A pump may indeed fix it, but you are rolling the dice. Check for power at the pump first, and also check the ground at the pump. Remember that you likely cannot return the pump if it turns out to be a fuse.

 

Checked the fuse its good, not sure how to test the relay and neither AZ or O,reillys had the relay I will have to go to GM, I will check the power at the pump tomorrow and the ground, Thanks for the tip.

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Is there any way to "adjust" the length by loosening any of the components and collapsing the assembly? Or is the entire assembly built in such a way that you cannot loosen any parts?

For example, if you have two steel lines that are connected via a rubber hose secured with two hose clamps, you could loosen the clamps and pull the steel lines away from each other to lengthen the assembly, or push them together to shorten the length, and tighten the clamps to secure it again.

 

Does the old unit have those rubber feet you mentioned, or is there any spot on the original pump where they could have been attached? Does the bottom of the new pump have sharp edges that make the rubber feet necessary to prevent the pump cutting the bottom of the tank?

Negative, the Amazon site was wrong, I sent the pump back and ordered the one a local parts store said would fit.

 

I drove fords(F150's) and Jeeps before up until last year, Jeeps rock but I need a truck I live on a farm, I have horses and need to haul a lot of things and I grew tired of fixing fords, the 5.4 was a pain in the A%% and the 4.6 motor didn't fair much better so I figured I would give GMC a try. So far I've fixed a lot more than I think I should have for a 07 truck, now this fuel pump issue or fuel sender issue, I bought this before the big recall owner deaths problem, I like this truck, and It will be with me for awhile, what else tends to fail at the 100k mark that I should think of replacing? I've already replaced the front wheel bearings. what else should I be checking?

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One thing I did notice was that when I turned the key it kind of stayed engaged when I let off of it like it was continuing to turn over even when I let off of the ignition. very strange.

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Don't know what know what "big recall owner deaths problem" was/is. I know that when ethanol started to become more common around here that many had issues with it damaging fuel level senders. The fuel sender on my GTP went screwy, it would read empty, but only take $10 to fill instead of the $50 or $60 it used to. First time it happened I thought something was really wrong since it was full Monday morning, and empty Tuesday night on way home from work. It was the first time I had bought the new high octane fuel (94 at that time) and since the GTP took premium due to supercharger, I tried the new stuff. Really thought I was only getting a quarter of the fuel mileage. GM replaced the sending unit a week later, and about 5 months after that I got a $25 gas card from the gas company that the fuel came from, along with a letter from GM saying they were not saying it was the gas that caused it, but here is a gas card from that company for the inconvenience. I only used that gas company for the lawn mower after the sending unit was replaced.

 

Wheel bearings are a maintenance item, along with brakes, front end parts etc. Fuel pump is the big price item that I do not think should fail as much as they do. Why they have to bury them in the fuel tank (with the filter right next them) seems not very smart to me. They know the pumps will fail, at least put a drain plug in the tank to make it easier, or put a access panel in the bed of the truck to access it.

 

I think the only other "weak" point is the transmission. If it is not treated right, it will give you issues. Generally, try not to abuse it, or overload the truck.

 

Your truck is 7 years old now, it used to be that the vehicle does not owe you anything at this point. 7 years is near 100k miles. I am not saying the truck is dead now, or is wore out, it just does not owe you anything. In other words, and repair that comes up now can be considered normal (short of engine or trans complete failure).

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I could be wrong, but the pump could be getting power from another source and the control module tells the pump how much to send and at what PSI... just a thought.... As a sys admin I tend to eliminate all the silly things before i touch the big items... if replacing a network cable can/would have fixed it why replace the switch?

 

I think the logic he is using is that if there is sufficient fuel in the tank, and if the pump is getting power, and he can hear the pump running, but there is no fuel coming out of it, then there is something wrong between inlet and the outlet of the pump. To me, that appears to be sound logic.

This may not be the actual pump itself, it may be the pickup filter on the pump, it may be the fuel filter built into the pump, it may be a crack in the inlet tube of the pump that is allowing air into the pump, it may even be enough crap in the bottom of the tank that it is blocking the inlet of the pump. All of these possibilities require removal of the pump to check.

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relay is good, trying to remove the bed now as I was told that was the best way to access the pump, I was able to loosen all the bolts but one on the passengers side closest to the cab, it just turns and makes a noise and wont come out, any ideas, or would it be easier to drop the tank?

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