$0D 16197427 Fuel Pump run time?

[EagleMark]

On a 16197427 $0D stock truck. Has had MPFI PCM and memcal mod done. WIth key on engine off, What would make fuel pump on time change from 2 seconds to 15+ seconds? Does fuel pump run constant in LHM?

[JeepsAndGuns]

0x4958, max time for fuel pump running with no DRP
BJYL stock is 10 seconds, as with most other $0D V8 bins I have seen. I tested it on mine and I turn the key on, and fuel pump runs for ~10 seconds.
Most $0E bins I looked at were 3 seconds. I think I raised it on my old 0E bin to make the fuel pump prime a little longer as I had a pump that the check valve in it that didnt work that great and would bleed off when it was off.

In my many mistakes and blunders in my tuning, it does seem like I remember that when the 7427 was in LHM the pump would run constantly when the key would turned on. I have forgotten to put my chip back in a few times in the past, and figured it out when the pump wouldnt shut off, and I couldnt get ALDL connection. Only started the engine once when I did this. Found out real quick something was wrong, as the IAC also peggs wide open....lol

[EagleMark]

Cool thanks! That was it, 10 seconds and I am used to 2, so I thought there was an issue.

[JeepsAndGuns]

Wonder why they went from 2 seconds in $42, to 10 seconds in $0D, but then 3 in $0E?
Seems odd.

[dyeager535]

Would it have anything to do with the hot fuel handling? $42 was running the hot fuel module in some setups, not sure about the other two. I've wondered why GM wasted the money on the hot fuel module when I figured the ECM could have handled the same task.

[EagleMark]

This is the fuel pump runtime if you turn key on and don't start engine. The hot fuel thing your talking about on HD trucks lets the fuel pump run 20 seconds after shutdown to cool TBI, avoid vapor lock was theory... it's a little gray box if you ever find one in a harness.