Fuel gauge help

[SSean]

Whats up guys. I need a lil bit of help here.
I have a 98 gmc single cab with a lil 6.0 I swapped in months back. But ive been having a problem with one thing. My gas gauge does not mark at all. Ive tried swapping the stock 350 harness for another one, nothing. and also changed the whole fuel sending unit, nothing as well. If anybody has any info or has had the same problem I would much appreciated some help. A friend of mine told me to ask yall because yall have the most swapped obs's.

[slow600]

mine didnt work at first either. i had cut the ground wire that goes to the factory thermostat housing. worth a shot.

[Lextech]

A stock Gen3 fuel calibration will not work the 98 gauge. Assuming the wiring is correct---It is the tune.

Jeff

[SSean]

A stock Gen3 fuel calibration will not work the 98 gauge. Assuming the wiring is correct---It is the tune.

Jeff

Well im tuned by flaco and itz a speed density tune, I have a 4-barrel throttle body. My harness...well itz actully 2 harnesses. One is the stock 350 vortec and the other is a Nelson Performance stand alone.
How would the tune make it mark the fuel gauge? You lost me. lol

[Lextech]

There are several settings in the PCM for the fuel gauge. Two of those settings definitely need to be changed for the Gen3 calibration to properly run the 98-2000 GMT400 gauge. I have no idea if your wiring is correct. Assuming it is, and your gauge works, then it is in the tune.

Jeff

[1991SSP]

Can the fuel gauge on a 1998 model be functional without being pinned into the new PCM??? I can't get mine to work at all, I have the purple wire for the gauge and the purple with white stripe from the tank spliced together and the gauge reads past full

[kewljay223]

There are several settings in the PCM for the fuel gauge. Two of those settings definitely need to be changed for the Gen3 calibration to properly run the 98-2000 GMT400 gauge. I have no idea if your wiring is correct. Assuming it is, and your gauge works, then it is in the tune.

Jeff

you say 98-2000 but what about the earlier years? i have a 95 that im about to swap a 03 lq9 in. will i be running into this same issue? will the tune need to be adjusted just like this or is it different? im not sure if the gauge gluster is the same.