Tune is turning my fuel pump off

[Smoky68]

I loaded a new tune on my truck and the truck starts and runs for about 3 minutes and then turn the fuel pump off. If I turn the pump on in the scanner it comes on, but it will not run with the regular tune, until I reload the tune then it runs again for 3 minutes and shuts down again. Please let me know what could be causing this issue.

Thank you,

Brandon

[Eaglegoat]

Not specific enough. Upload both tune files. Have you reloaded the old tune?

[Smoky68]

I reloaded a the old tune and the problem still exists. I will load the tune when I get home...I don't have it on my work computer

[Eaglegoat]

If the old tune does it too it's probably not a tune problem.

[Smoky68]

That's kinda what I thought...I was asking more along the lines of has anyone ever had this problem...

[CRTD]

That's bizarre. I would say it is probably a coincidence with the tune aspect. I would perform routine diagnostics and find out for sure the fuel pump relay is being shut off by the computer before I blamed the tune. There were quite a few GM trucks that had fuel pump connectors made from MP150 terminals which are only rated for up to 15 amps. A new pump will run at 10-12 amps for 60 psi. Slow the pump down a little with a dirty fuel filter and now you have even more amperage. They have since been upped to GT280 terminals which can carry more current (25 amps).

[Smoky68]

I did a complete rewrite with the exact same tune and the problem went away...didn't change anything else. I wondering if my ECU isn't trying to fail on me.

[CRTD]

If you don't test it you'll always be guessing. Set up a low current test light on the PCM control side of the fuel pump relay. If the light goes out before the engine dies then there is a problem related to that ckt. If the light goes out after the engine dies it is not the cause of the engine stalling.