07 Fuel pump replacement - pump only not entire basket

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10-12-2010, 08:13 AM

#21

pl4yboy

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Quote:

Originally Posted by Tootall

Swapped the pump with a Walbro, same problem....

Any details on that check ball?.... just replace the entire basket?

Fuel pressure is all over the place. Truck fired up with out the relay on the fuse box and drove it the rest of the way home, very weird

I don't really have details on it. Someone mentioned that there was one in the assembly when I was having issues. I swapped the assembly and it's been 100x better. I do know that it is built into the top of the fuel assembly. I looked for it because I was going to just do a return style system to fix my issue... like drill it out and convert to external regulator and filter. I couldn't find it. But a GM tech told me that this was a pretty common issue on the NNBS. I'm still having fueling issues, but now it's way too much fuel. Driving I'm at 64-70 psi, which is fine with me. I've tuned for the extra pressure.

If pulling the relay fixed your truck, it would lead one to believe that is is an electrical issue. I don't know if you have a variable speed fuel pump like I do, but there is a fuel control module on the back cross member above the spare tire. If you have one, I believe your problem may be more electrical than anything. I know you don't want to replace that part though. You're looking at 750$ through a dealership.

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10-12-2010, 05:14 PM

#22

Tootall

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still not fixed . . . open for suggestions

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10-12-2010, 06:36 PM

#23

charcold-bowtie

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can u log pump voltage? not sure if its even a pid... And see if the motor is swinging a lot, if not, it would have to be a regulation problem.

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10-13-2010, 12:26 PM

#24

Tootall

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Quote:

Originally Posted by charcold-bowtie

can u log pump voltage? not sure if its even a pid... And see if the motor is swinging a lot, if not, it would have to be a regulation problem.

funny that you mention that. . . I pulled the relay from the fuse box under the hood . . . and it still ran for 15 minutes . . . . .

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10-14-2010, 12:56 AM

#25

pl4yboy

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Quote:

Originally Posted by Tootall

funny that you mention that. . . I pulled the relay from the fuse box under the hood . . . and it still ran for 15 minutes . . . . .

The relay only kicks the pump on, not keeps it running.

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10-14-2010, 01:13 AM

#26

charcold-bowtie

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relay will kill my truck instantly

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10-14-2010, 07:59 AM

#27

Tootall

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Quote:

Originally Posted by charcold-bowtie

relay will kill my truck instantly

same here . . . he's replacing the intank regulator this weekend . . . we'll see what happens

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10-15-2010, 12:33 AM

#28

pl4yboy

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Quote:

Originally Posted by Tootall

same here . . . he's replacing the intank regulator this weekend . . . we'll see what happens

That will be interesting, seeing as how I've had the pump out multiple times... you can't simply replace the regulator. If you had the pump out you would realize that the regulator is a check valve built into the top of the fuel pump assembly. Unless he is replacing the whole assembly...

Call any dealership and ask them if you can buy a fuel regulator for the NNBS. You can't.

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