Check post #16 and post the results, they will tell what to check next. If the dash gage goes past full, there's a short in the tank. If it remains on empty, then we'll need some resistance and voltage measurements.

 

unhooked the plug with 4 wires going to it. Can't tell the colors as they are in the loom but when I started the truck it wouldn't run as the fuel pump wasn't running. I assume that's the correct plug.

And...the fuel gauge didn't wiggle at all when I turned it to run, but didn't crank it.

 

I think this is one of our guys, might help with your meter.

 

Disconnect the fuel pump module connector. Set the range selector on DC volts, (just like the image in post #21). Connect the black probe to a good, clean chassis ground, (no paint, or rust). Turn the ignition switch to the run position, (engine off). Touch the red probe to the purple wire terminal in the harness connector for the module. Should be ~5 volts. Post your results.

 

I'll try to get to that tonight. I'll need someone to turn the truck to run while I'm holding things below so maybe the wife will do that, but she has a cold so maybe not.

Another thought: When the same thing happened on her van it turned out to be the connector halfway from the pump to the engine. Is there another connection somewhere on the blazer between the pump and the fuze box that I should be checking too?

 

No body ever likes my ideas. Try a garden pump sprayer filled with cheap green anti-freeze. Wait two hours then take it to a car wash with an under-body spray.


Work's out here when our boat motors get all salt crusted up

 

The purple wire runs from the fuel pump module connector to the PCM on the right inner fender, there are no other connectors. Keep in mind, you're looking for a short to ground, not an open circuit. Might be worth checking both terminals on all fuses with a voltmeter.

 

Is there a particular fuse that I'd be looking for?

 

There is no single fuse for the fuel gage. The PCM, (Powertrain Control Module) supplies the purple wire with reference voltage, (just under 5 VDC). The fuel level sender applies ground to the purple wire depending on how much fuel is in the tank, (more fuel = less ground applied). The fuel level data is used by the PCM for several different monitors. The data is also shared with the BCM, (Body Control Module) through a netwrok. The BCM supplies the IPC, (Instrument Panel Cluster) with fuel level data, and a logic module in the IPC sends the data to the gage.

If you're going to check fuses, check both terminals of all fuses in both fuse panels. Use a volt meter and make sure the ignition is in the run position. Do not remove the fuses to check them. Probe the terminals on the top of the fuses. At this point, it's easier to check the purple wire for the presence of reference voltage, (post #25).

This information applies only to 1998 and newer.