Good morning fellas

So I have a 1987 efi lariat cut 302 engine.

The fuel gauge for the rear pump stays on full all the time. And I thought okay sending unit going out but I'm not so sure now. The reason being is because the other fuel gauge works and I'll switch the fuel to the rear tank and switch it back after 10 miles and the fuel gauge on the front tank is lower. So in short I got a oh phantom rear tank showing fuel but even switch on the rear the front tank gas is lowering. What's going on?

 

Sounds like the check valve and sensor are hit in the rear tank, that is if it's actually filling from the front and not just reading full.

If you are going to replace the pump do it with a motorcraft pump otherwise you may be doing it again in just a few years.

 

It's reading full on the rear tank. The front tank is reading fuel good. Doesn't matter which tank I switch to, the front tank gets rid of fuel not the rear.

 

Could be a bad switch, maybe.

 

Switch it to rear and have someone stand or lay beneath that tank, turn the key to run, is the rear pump priming with the rear tank selected?

 

what did you figure out on your fuel tanks. I have the same problem but my rear tank is always on empty.