[FIXED] 1997 Chevrolet C2500 5.7 vortec fuel pump amperage

Hi Scanner Danner,
I just watched your '99 suburban video. (GM Fuel Pump Relay Testing) Great video! I learned a lot, thank you. I have a 1997 C2500 5.7, (bought new, cared for, now has 229,000 miles and looks a drives like new) and I'm curious about amperage. I'm drawing between 9 and 10 amps. I used my Fluke 337 clampon amp meter on the wire to pin 30. The reason for all of this is the 30 pin got so hot it cooked the surrounding plastic. I repaired everything and now for the first time, I'm checking for heat and finding some after a 10 minute drive. 30 and 87 are hot to the touch. Is this normal, or could this be a sign my pump is going out? I'm on my third pump. First one died of low pressure. Second one didn't work after a six hour drive. I appreciate your help.

Hey sir! Welcome to the forums!

I'm OK with the 9-10 amps you measured, pretty typical for this system. The pins being hot to the touch is somewhat worrying, but it's not unusual for underhood relays to get hot during normal operation. Even lower current circuits like A/C compressor clutches can get their relays pretty warm just driving down the road.

What kind of repairs did you do on the relay box? I ask because burnt pins like that are usually the result of poor connection, instead of an overcurrent from a failing pump/motor. If possible, you could voltage drop the connections to verify no losses, and therefore no excessive resistance.

Yes, I understand and agree 100%.

For the repairs, I opened up the distribution box, released the pins one by one and moved them to a new, clean location. I moved my horn relay over one (to where the AIR pump relay would be) and moved my fuel pump relay down one, to where the horn relay used to be. Then, I got some new crimp on terminals (from the gm dealer) and after removing and replacing a few inches of baked wire, crimped the new terminal on. I parallel crimped the replacement wire to the existing wire. Before shrink wrapping everything, I soldered the new crimps. The other four terminals were in great shape. I finished up with a little dielectric grease.

mrredbailey wrote: For the repairs, I opened up the distribution box, released the pins one by one and moved them to a new, clean location. I moved my horn relay over one (to where the AIR pump relay would be) and moved my fuel pump relay down one, to where the horn relay used to be. Then, I got some new crimp on terminals (from the gm dealer) and after removing and replacing a few inches of baked wire, crimped the new terminal on. I parallel crimped the replacement wire to the existing wire. Before shrink wrapping everything, I soldered the new crimps. The other four terminals were in great shape. I finished up with a little dielectric grease.

Sounds good to me. Nice thinking by moving the relay pins around, too. Anyone else that goes into that relay box is gonna be super confused, but it works! :lol:

Tyler wrote: Sounds good to me. Nice thinking by moving the relay pins around, too. Anyone else that goes into that relay box is gonna be super confused, but it works! :lol:

Thanks. I thought about the confusion and I have two thoughts... One, I can update the picture in the lid. Two, I have zero intention of getting rid of this truck. I ordered it new and put just about every mile on it myself. I love this truck.

A little follow up... after driving the truck a second time and checking the relay again, I felt the a/c relay also and it's just as hot (like Tyler mentioned) as the fuel pump relay. So, I guess all is well.

Surprising how hot those little suckers get, eh? :lol: Sounds like a fix to me!

Just curious, what brand were the first two pumps? The low pressure and the six hour special.

Yeah, in the machine tool industry, I'm not used to relays getting hot.

I don't recall the brands of the two pumps; I purchased them at one of the auto parts stores. First pump was replaced at about 75,000 miles and the second one was replaced around 170,000 miles. Where the six hour comment came from was I drove from Ashville NC to Cincinnati without shutting it off. Came out the next day and nothing, no sound, nothing. I threw a new pump at it without testing first. I also pulled the relay before starting that job, so I'm starting to wonder if was just a dirty pin.

mrredbailey wrote: I don't recall the brands of the two pumps; I purchased them at one of the auto parts stores. First pump was replaced at about 75,000 miles and the second one was replaced around 170,000 miles. Where the six hour comment came from was I drove from Ashville NC to Cincinnati without shutting it off. Came out the next day and nothing, no sound, nothing. I threw a new pump at it without testing first. I also pulled the relay before starting that job, so I'm starting to wonder if was just a dirty pin.

Ah OK, I misunderstood! Here I was thinking you'd gone through three pumps in a weekend. :lol: