jda51

2000 ISB 5 speed. Should the FASS be wired directly to switch power so it runs all the time or to the ECM like the orginal lift pump?

AlpineRAM

I'd strongly suggest that you let the ECM drive a solid state relay that powers your FASS.

A switched power source will still be live when the airbags deploy, so a nice diesel shower to add zest to your burning wreck is quite probable.

And with the ECM controlling the FASS you caqn bump the starter to run it for 30 seconds and also get 50% duty cycle on startup if you use a solid state relay.

jda51

I contacted FASS and here is their reply
Hello David-



We no longer wire the trigger for the pump to the factory lift pump connection. As the 98.5 to 02 Dodge trucks get older, we see more ECM issues that cause the lift pump to not operate correctly. Wiring it to a key on fuse is a more reliable power source.



Thank you,



Gene Brown

Customer Service/Technical Support Supervisor

Diesel Performance Products Inc.

FASS Fuel Systems

16234 State Hwy. O

Marthasville, MO 63357

KATOOM

Wiring it the way FASS states in their email will result in no prime cycle of the fuel pump and any other cycle options.

jda51

I decided to wire the FASS thru a relay triggered by the ECM. This method effectively lowered the starting fuel pressure and seems to have helped the long start problem when hot.

KATOOM

You can also wire in a delay relay which interrupts the fuel pump signal run time when the ignition key is in the START position. This retains all factory fuel pump run cycles but prevents the fuel pump from pumping during engine cranking, which also is what the VP injection pump prefers because it removes stress on the fuel solenoid and timing ring solenoid until the engine starts, which is the reason for the hot hard start issue. If you're interested in seeing how this is done, I can link the diagram on how to wire it up.

jda51

Thanks, I would appreciate that.

KATOOM

KATOOM

Thats just a 5 pin relay you can pick up at NAPA or any other parts store. Just make sure you get one with the pin switching action for 87 and 87a the correct way otherwise it wont work.

jda51

thanks