My son is working on a 1988 STX Ranger. We discovered it has two fuel pumps. The one in the tank is described in the Haynes manual for 1985-1988 models as a low pressure pump and the one bolted on the frame is called the high pressure pump.

The "typical" wiring diagram shown for the 2.9 liter does not have any reference to the two fuel pumps. Is the second "high" pressure pump wired in the same fashion as the "low" pressure pump? We finally got the low pressure pump working, but not sure if the second high pressure pump is. The truck runs and idles, but we haven't driven it yet.

 

Why does no one answer these questions?

Is there a better forum where you can actually get information?

 

Apparently no one is familar with the "two pumps."

There are other forums where there may be someone who is.

 

Hey i am a new member but i think i can help u. If it came with two pumps it def needs two pumps. to quickly check if both pumps are working put a high pressure fuel gauge on the fuel rail. unplug high pressure pump and start the truck, if it runs on the low pressure pump, have your son plug in the high pressure pump while u watch the gauge on the fuel rail....it should jump up a bit then stable out... it works then!!!!

 

I can’t imagine it would run very well on just the low pressure pump. If you don’t have a pressure gauge sometimes you can find a capacity spec.
like a like a liter in 30 seconds or whatever it may be, get a container and be careful with raw fuel. Disconnect and power the pumps. If your container
is full to the capacity your pumps are good. They make a little noise usually to. But voltage drop and or fuel pressure are your best tests.