1996 Chevy Blazer Fuel gauge

MARC123

MEMBER
1996 CHEVROLET BLAZER
6 CYL
4WD
AUTOMATIC
170,000 MILES

Help Please, having problem with fuel gauge,

1 month ago.
I changed Fuel Tank, and entire Fuel Pump Assembly
that came complete with pump and sending unit and moduals on it, everything was fine till now the fuel gauge started to go crazy. At half tank it will go to full then back to half over and over, now it rotates in complete circles and hits the voltage gauge below it,

Could it be possibly a bad Ground? Or I heard of a Voltage regulator for gauges?

The new fuel pump ass. Is a Delfi? Is that a good one or cheap manufacture,

It took hours to put this in and hate to drop the tank if its something else.

Thank you

1 Reply

MATHIASO

MECHANIC
1,209 POSTS

A short in the sending unit or wiring on a GM system would cause the fuel gauge to read empty, therefore, while an open in the sending unit circuit would make the gauge read full.
If only the fuel gauge is acting up, you can rule out the voltage regulator as a possible cause. The problem is either in the gauge itself, the sending unit or the wiring in between.
Check the gauge's internal resistance with an ohmmeter. You should generally find somewhere between 10 to 15 ohms resistance. No resistance would indicate a short in the gauge while very high resistance would indicate an open.
You can fabricate some resistor jumper wires by buying a 5 ohm and 80 ohm resistor at a local radio parts store. Connect each resistor to a fused jumper wire and use them to simulate high and low sending unit readings. The jumper wires (or test box) can be used either at the gauge or sending unit.

Another way is to remove the sending unit from the tank, reconnect it, turn the key on and move the float arm up and down while watching for a change in the gauge reading.