Fuel pump questions

[falcon]

Hi guys. I've got a K5 blazer, 1989 with a FI 350. All of the sudden I'm having lots of problems with my fuel pump in the gas tank, it seems to be burning them out as I've gone through 3 pumps and its sitting again as I type.
I've installed a new ground wire and cleaned the contacts, clean gas, new filter,etc. But as soon as I think my problem is solved the pump is dead again after very few miles.
Did some more checking today, and right at the top of the sending unit where the wires come into the pump I have 8 volts coming to there. Along the frame before the wires come to the pump there is a harness where I also have 8 volts. But at the bottom of the sending unit where the wires from the top connect to the pump there is only 6 volts. As soon as I install a new pump it runs right away and seems fine, but doesn't last long.
So I'm hoping somebody can tell me where to start finding a solution to this problem. Why do I only have 8 volts to the top of the sending unit and 6 at the bottom? Do I need a new sending unit? Not sure which way to go as I don't know if 8 volts is my problem or not. If it should be 12 volts where do i start looking? TIA.

 

[bigblock72]

After that many pumps I'd be willing to bet your sender is cooked at the connector. Usually they'll overheat the terminal for the gray wire (fuel pump power). Inspect the connector terminals real close on all of the connectors if they look like they're even a little discolored from heat or corrosion it's time to replace. That includes the truck harness connector, the sender connector truck side, the sender connector inside the tank, and the connector at the fuel pump. The connector pigtails are all available new so don't worry about scrounging around for used stuff.

Did you replace the filter after the last pump replacement? A restricted filter will overheat the pump and all of the connectors in a short time so keep the filter replaced often.

 

[dyeager535]

Check your fuel pump power wires...relay and oil pressure switch. Fuel pump relay wires tend to get ugly right at the connector.