Still have problems with Fuel lift pump.

[Glenn C.]

I put a switch on the dash that I can turn the lift pump on and off with manually to start the truck.The truck runs fine after I get it started, even on a recent trip of 3000 miles but I know this is not the way the lift pump is supposed to work. I ,today, ran a jumper wire from the pink wire on the solenoid on the injection pump to the "F" wire on the relay, and when I turn the key on, the pump comes on and the truck starts right up. But the pump continues to run after the motor starts and is running.
1. Will this burn the lift pump up?
2. Is there something that I have found that has been causing my problem all along?
Thanks in advance.

[BUZZ]

Hi,
Your lift pump is supposed to run as long as oil pressure is present, engine running, or your are starting the engine. IF your lift pump is not running likely your oil pressure sending unit has failed. This is very common and will continue to fail until you wire in a relay to carry the lift pump load.
If you need more detail let us know.
Happy New Year
Buzz

[rjwest]

What year truck. 96 and later are different, Oil pressure sw is only back up. There is a relay controlled by PCM.