So I understand the fuel pump on my 88 S10 blazer has two sources of power. One from the fuel relay and the second from the oil pressure sensor. Is this correct? In trying to run down a issue I have disconnected both the relays by the driver's side fire wall and the oil sensor adjacent the distributor. The truck is still running the same. The fuel pump is still getting power.

Why is this? What am I missing?

The issue I was running down was the truck would start to lose power like it wasn't getting enough fuel then if you shut it off it wouldn't restart. It will start again after sitting a long time.

I thought maybe I had a bad relay and a bad oil sending sensor both out or working intermittent or one one out and one working intermittent.

I can't really fix my issue till I can recreate it to see what's causing it. Any ideas?

 

2.5, 2.8 or 4.3L engine?

George

 

it's a 4.3

 

Depending on your configuration there are up to three sources of power to run the fuel pump:

The oil pressure switch
The fuel pump relay
The redundant fuel pump relay
Fuel pump priming tab (if energized or hacked)

All three/four output power on Gy (or Tn/Wht) wires which have a splice/junction on the way to the fuel pump motor.

See attached.

George

 

Thanks, I will figure out if the priming tab has been jumped. That's all that's left unless I'm mistaken about the location of the redundant relay.

It's not really an issue, I just want to know.

the issue that got me on this has been resolved. It was a bad ground wire into the fuel pump. I went ahead and replaced the pump and sending unit.