1996 S10 Blazer New Fuel Pump Fuel Guage Not Working

[fazd]

I put a new fuel pump in my 1996 s10 blazer and the truck does run fine now. The problem is the fuel guage is stuck on empty. It is not a GM fuel pump, it is one of the ones you have to change the wiring harness. My Battery was disconnected for few days.

[old_master]

If the fuel guage worked before you replaced the fuel pump module, it could be one of several things: The float arm got bent and is stuck down, the fuel level signal wire was connected incorrectly when you replaced the harness connector, or the fuel level signal wire got shorted to ground during reassembly.

[Emmitt101]

I just repaced the pumpin my 96 and instead of reading empty it read full. I needed to replace the vent valve because it broke during removal of the tank anyway and when I lowered the tank sure enough the purple wire on the harness had become unconnected. Instead of using the butt connectors this time I used the Male/Female spade connectors aand used shrink tubing and solved problem. Hope this helps.

[fazd]

Thanks for the responses. I am not sure what you mean here:

"or the fuel level signal wire got shorted to ground during reassembly. Or it could be a shorted, (to ground) fuel level sender"


I can easily see the wires that connect to the pump. Do you think if I use a test light I can test each wire after the reconnect to see if there is power? With the key turned on? Emmitt101 mentioned the purple wire. I am not sure if this is the wire for the fuel guage. My fuel tank is brand new also.


Another note. I put one fuel pump in and it was defective. It was brand new and worked for 2 days. So this is the second fuel pump in a week. This fuel guage went right to full and was stuck there for one day then started working correctly the next day. I drove now on the new fuel pump for 80 miles.

[old_master]

Thanks for the post Emmitt. If the purple wire has an open circuit, the guage will indicate full. If it's shorted to ground, it will indicate empty.

[old_master]

The purple wire at the fuel pump module connector is the fuel level signal wire. It runs up to the back of the instrument cluster and connects, through a printed circuit, to the fuel guage. There is a spur circuit spliced into the purple wire that runs to the ECM which is used for the EVAP monitor.

With the connector at the fuel pump module disconnected and the ignition switch in the RUN position, the purple wire should show battery voltage. There are 2 black wires in the module connector, both should have less than 5 ohms resistance to ground.

[fazd]

Good info. I will be testing this in the morning and post my results.

[fazd]

Final Update: I did test the wires with a regular test light and there was power to the purple wire. It was real faint. So I took tank and pump out again. Once I removed the pump I could tell the arm for the float was not swinging real freely. When I looked closer at it I could tell the little metal bar the float is on was not popped into socket all the way causing it to rub some plastic on the outside of the arm. The aftermarket one has some plastic on the outside of the arm as the gm one doesnt. Once I popped it back into place it was amajor difference in how free it swings. I did plug in in with it not in the tank to be sure the guage moved and it did. I am pretty sure the arm was like this when I put it in so it was basically my fault for not knowing better.

Thanks for help.

[old_master]

Not your fault, it should have been ready to install right out of the box. Good job finding the problem, glad you got her fixed.

[Rick Norwood]