How do you check the sending unit at the pump to see if its faulty. I know it involves unplugging it but after that I'm not real sure. It's on a 1989 s10 blazer

 

i think you might have to take it out to test it. i havent messed with one in a very long time, but i remember you have to do a ohm test on it. it will read different ohms depending on where the float is at.

 

Well I know there is a way to check it at the connecter harness on the frame but I've forgotten some of the details

 

At the fuel pump there is a 2 wire harness and a ground strap to frame. Tan should be 12v key on (priming or KOER) Pink wire should be the sender. At empty position reading should be 1 ohm,...... at 1/2 full 44 ohms,........ and 88 ohms at full position. If over 90 ohms or less than 1 or open circuit -sender is faulty.

Only way to truly test it is to take out the pump, otherwise guesstimate what's in the tank and check again after filling.

 

I know what's in the tank. But the gauge is stuck at full. My problem is that my dash is digital. So I'm pretty sure it's the sending unit itself but I'm trying to make sure. The gauge started acting up the same time I started having fuel pump issues so I'm guessing they're connected.