Hello all!

Ok, got some questions...

I have a 1993 Chevy Silverado, K3500 6.5 TD dually, Lift pump seems not to be working.

1. Where is the Lift Pump "relay" located, my Helms books are in CO, I am in NM...

2. Where is the "inline fuse" Located?


Got a new Lift pump anyways since I run allot of SVO.
It's a FASS lift pump. I figure I have washed out the seals in the Delphi lift pump.. Got under and double checked, for VDC, no volts...

Last q,

3. 1 to 4 PSI for for the lift pump? This fass pump is a monster pump, i swear the vendor was telling me like 15 to 30 PSI...
What is the safe upper PSI limit?


Found the OPS, I will change it., But I am thinking this is a relay..

Thanks all.

There is no lift pump relay, from the factory the LP is run solely by the OPS, when the OPS sees more than 5 psi of oil pressure it sends power to the LP. however the OPS is a weak spot, and many guys add a relay to take the load off of the LP.

Th factory pumps usually run between 10-15 psi and 30-50 gph, the max pressure you want to run is about 20 psi, anything higher can damage the pump. An inline fuel gauge is a good idea for tuning in the new pump.

Hope you like the FASS system, it is a sweet setup!

There is no lift pump relay, from the factory the LP is run solely by the OPS, when the OPS sees more than 5 psi of oil pressure it sends power to the LP. however the OPS is a weak spot, and many guys add a relay to take the load off of the LP.

Th factory pumps usually run between 10-15 psi and 30-50 gph, the max pressure you want to run is about 20 psi, anything higher can damage the pump. An inline fuel gauge is a good idea for tuning in the new pump.

Hope you like the FASS system, it is a sweet setup!
Thanks very much!!!

You can put a relay system to override the OPS and give more reliable curent to your new FASS. I am not sure if FASS comes with one? Otherwise, just search the FAQ.