New Fuel Pump and Sending Unit... now gauge won't work

[NousDefions]

Quick background (new member!):

I recently purchased a '97 Tahoe from a friend, and the first week I had it the fuel pump went out. No big deal, although it was a pain to change since it had 3/4 of a tank.

I replaced it with an AC Delco fuel pump (with the new harness), and the pump works great, but now the fuel gauge doesn't work.

When the ignition is off, it shows about 1/8th of a tank. Once the ignition is in the "on" position, it goes to the 3 o'clock position (past full) and then settles firmly at zero.

Did I wire the harness incorrectly or something? I don't know the pinout of the harness, but my first instinct is that one of the four cables isn't connected properly.

Thanks in advance for any help!

 

[SunlitComet]

your sender wire is disconnected causing high reading when power is on. if it drops to empty then gauge wire it is shorted to ground.

 

[SunlitComet]

BTW

 

[NousDefions]

your sender wire is disconnected causing high reading when power is on. if it drops to empty then gauge wire it is shorted to ground.

Thanks!

Of the four wires (purple, gray, black, and black), which is the sender wire and gauge wire?

 

[NousDefions]

Ugh... it is NOT a '97... it's a '98. I just got the title today.

So, since it is a '98 and I didn't know it, I put a '97 fuel pump in it. Apparently the fuel pump is a different model for the '98 models. Could that be the reason that my fuel gauge isn't working? The fact that I put a year older sender unit in the truck?