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Jdavis51

Fuel system nightmare

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Hey everyone I’m a new member so if this topic is in the wrong area please just let me know. I have a 2007.5 GMC Sierra slt with a 5.3, it’s an extended cab 4wd as well. The issue I’m having is that I have no fuel pressure at the rail, I have disconnected the fuel line at the pump and it is pumping but I haven’t tested the psi. This is the 2nd fuel pump I’ve put in the truck and I also replaced the fuel flow controller that’s on top of the spare tire. I can blow air through the line and air gets to the other side so there is not a full blockage somewhere. The truck was running but would lose pressure and Rpms would drop for less than a second once every few minutes but now the truck will not start at all. The truck has had the issue now for 6-7 months and has been not running for about the last month. Any help at all would be very much appreciated as I have no idea what else to do.

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Double check the fuel pump part numbers to match your truck. The pump should have 60 psi at the rail. If it isn't trying to squirt back to the front of the truck almost you probably aren't getting that 60 psi. I installed a precision pump from O'Reilly's and have had no issues. Also try to siphon or drain the tank and make sure there isn't a bunch of trash in your tank stopping up your fuel filter right as you put it in. Was the issue resolved after the new pumps were installed?

Sent from my Pixel 3 XL using Tapatalk

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5 hours ago, Jstevens7700 said:

Double check the fuel pump part numbers to match your truck. The pump should have 60 psi at the rail. If it isn't trying to squirt back to the front of the truck almost you probably aren't getting that 60 psi. I installed a precision pump from O'Reilly's and have had no issues. Also try to siphon or drain the tank and make sure there isn't a bunch of trash in your tank stopping up your fuel filter right as you put it in. Was the issue resolved after the new pumps were installed?

Sent from my Pixel 3 XL using Tapatalk
 

I put the old (2nd) fuel pump back in and I have pressure now where it will fun but I’m still having an issue while driving. The rpms go down and you can feel the truck slowing down quickly since it’s still in gear but this will only happen for about a second every minute or so it still idles fine. 

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check that fuel pressure is being maintained when you rev up the motor.  When I bought my truck, the fuel pump could maintain 60 psi at idle, but revving the motor, the fuel press would drop to below 30 psi and stay there.

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3 hours ago, davester said:

check that fuel pressure is being maintained when you rev up the motor.  When I bought my truck, the fuel pump could maintain 60 psi at idle, but revving the motor, the fuel press would drop to below 30 psi and stay there.

I’ll check that when I get some time I did check pressure at idle and it was maintaining 60 but I’ll get someone to watch while I rev.

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