Fuel pump sycles and stays on????

[Smokin Joes 2500]

I just installed a Hypertech Stage 3 tune via the programmer and a BD-X Power. Now when I turn key on and wait for start light goes out, the fuel pump never kicks off. I hear the pump vibrate and I hear like a hissing or wooshing sound from under the hood. (seems like its coming from filter area, but might be my imagination cause its fuel related) Any ideas, maybe the Hypertech???

 

[AMassaro]

Why is it that the fuel pump cycles off? Just asking because the way I have mine setup, it's on as long as the key is on???

 

[rbattelle]

Through 2004. 5 the lift pump would only cycle for 2 seconds (same as the WIF light bulb test), then shut off until the engine was started. This is how my truck works.

But in 2005 they changed the ECM programming to keep the lift pump running for 30 seconds when the key is turned to RUN. I personally believe this was done because it ensures against even the briefest interruption of fuel flow to the CP-3 during the start cycle (which should help ensure proper startup).

My guess is that the Hypertech program you fed it included this new programming logic.

I believe the latest code for the CM-845 controller (2003-2005) includes this programming change, so if you went to the dealer and asked for the latest ECM flash program you'd have the same result.

Ryan

 

[AMassaro]

Thanks for the info Ryan. Is there any problem, in your opinion, with the way mine is wired? Key on, pump on???

And why would they cycle the pump on then off... I don't understand the reasoning for this?

 

[Smokin Joes 2500]

Through 2004. 5 the lift pump would only cycle for 2 seconds (same as the WIF light bulb test), then shut off until the engine was started. This is how my truck works.



But in 2005 they changed the ECM programming to keep the lift pump running for 30 seconds when the key is turned to RUN. I personally believe this was done because it ensures against even the briefest interruption of fuel flow to the CP-3 during the start cycle (which should help ensure proper startup).



My guess is that the Hypertech program you fed it included this new programming logic.



I believe the latest code for the CM-845 controller (2003-2005) includes this programming change, so if you went to the dealer and asked for the latest ECM flash program you'd have the same result.



Ryan

Kinda what I thought... . I figured if the fuel pump was staying on, it doesnt matter cause, the fuel pump stays on while the truck is running. Just wondered about it cause my 05' I didnt notice it on that truck. It sure runs strong though with the 2 boxes WOW Dont think Ill ever be able to drive a stock one again. RBattelle we'll have to get together sometime and roll some coal, your only a couple a hours from me.

 

[rbattelle]

Thanks for the info Ryan. Is there any problem, in your opinion, with the way mine is wired? Key on, pump on???

And why would they cycle the pump on then off... I don't understand the reasoning for this?

Shouldn't be a problem at all - key on = pump on. The pump cycles off after 30 seconds probably in case the owner has the truck in "RUN" for a long period of time without starting the engine. Leaving the pump on could drain the batteries.



Why would anyone leave the truck in "RUN" for a long time? I don't know, but I do know people do a lot of strange things.



[I do believe, however, that if you leave the key on RUN without starting the engine for more than 2 minutes a check-engine-light will come on... I've never tried it. ]



Ryan

 

[jakprince]

One problem with the pump running whenever the key is on is if you wreck and break a fuel line it could keep feeding a fire.