Fuel Pump replacement questions.

[SuperTramp]

Fuel Pump replacement questions. My ‘98 k2500 5.7 fuel pump doesn’t activate (make a sound) when I turn the key to accessory. I replaced the relay (thinking that might be the problem). The fuse for the fuel pump is still good. Are there any other things I need to check before replacing the pump? I have a full tank of gas (32 gallons) and spent time under the truck today trying to see If I could still reach the strap bolts with a floor jack and a 4’x2’ piece of plywood bolted to the business end of the jack to support the tank so I could lower it safely. I can’t reach the bolts. I can’t figure out how to siphon some of the gas from the tank. Any ideas? Thanks in advance.

 

[Uncle Ben]

You could try loosening the bed bolts on the passenger side and take the bolts off on the drivers side, then lift up the box on that side and prop up the box with a couple boards. Should give you enough room to change the pump and not have to drop the tank.

 

[SuperTramp]

You could try loosening the bed bolts on the passenger side and take the bolts off on the drivers side, then lift up the box on that side and prop up the box with a couple boards. Should give you enough room to change the pump and not have to drop the tank.

Ok. Thanks

 

[Schurkey]

My ‘98 k2500 5.7 fuel pump doesn’t activate (make a sound) when I turn the key to accessory.

Why would the fuel pump run in "Accessory"?

The fuel pump runs in "Crank" and "Run" for a 2-second prime, and runs continuously provided the engine has oil pressure or the computer senses engine RPM, but the pump won't run with the key in "Off" or "Accessory".

GM provides a bypass method to run the fuel pump. On my Luminas, there's a separate wire by the battery that, if connected to B+, will power the pump.

Seems to me that there's a wire in the ALDL connector on these trucks that can be jumped to power the pump.

The answer is in the service manual.

 

[Andrew Reynolds]

There is a fuel pump prime connector on mine. Put 12v to that and it will run the pump. That’s how I drained my tank as well.

 

[PlayingWithTBI]

Terminal G on OBDI not sure about OBDII

You must be registered for see images attach

 

[TerryKing]

Then there's my approach: Carefully figure clearance and use a sabre saw with a metal blade to cut a rectangular hole in the rear floor. File the sharp edges a little. Cut a piece of 1/2" pressure treated plywood 3 inches bigger both ways. Screw/glue the removed metal piece evenly on the plywood.

After replacing and testing the pump and maybe the tank adaptor (Rust Much??) place the metal/plywood patch back so the metal aligns. Hold in place and pilot/screw it into the floor in 6 or 8 places. Then remove it and use the caulk of your choice on the overlap section. Reposition and screw in place. Oh, put the carpet you removed back in place.

I have photos of this somewhere... Hmmm... I'll look

Some Japanese / European cars already have a removeable panel for the fuel pump. NICE guys!

Now YOU have one...

 

[Mark Gilbert]

Why would the fuel pump run in "Accessory"?

The fuel pump runs in "Crank" and "Run" for a 2-second prime, and runs continuously provided the engine has oil pressure or the computer senses engine RPM, but the pump won't run with the key in "Off" or "Accessory".

GM provides a bypass method to run the fuel pump. On my Luminas, there's a separate wire by the battery that, if connected to B+, will power the pump.

Seems to me that there's a wire in the ALDL connector on these trucks that can be jumped to power the pump.

The answer is in the service manual.

The 98 PCM actually completely controls the fuel pump, it doesn't use the oil pressure switch anymore like the TBI motors did. Just for future reference

You could try loosening the bed bolts on the passenger side and take the bolts off on the drivers side, then lift up the box on that side and prop up the box with a couple boards. Should give you enough room to change the pump and not have to drop the tank.

This is exactly how I did mine and it worked great. Although I am fortunate that I live in AZ where rust is less of a concern.

 

[WalkingBlackBear]

I went with the "ghetto" method and cut a flap in my bed. There are YouTube videos that give the cut measurements. Reciprocating saw, metal blade, shallow angle ... my pump also went last month the day after filling it up. Didn't lose any fuel. And if you have a slide-in bed liner, or a tool box ... nobody will see the cuts. Isn't pretty ... but it works if your bolts are rusted beyond repair, which they are after 22 years of Canadian winters here.

 

[Coveman]

my pump got louder over time and when I couldnt hear it prime anymore it was dead (no fuel pressure). I got one more run out of it by whacking the tank with a 2x4 and was able drive it and dropped it at the shop.

it was a full 44 gallon tank on my burb, didnt want to mess with it at home. Went with a delphi replacement