Like 5-10 MPG literally :(

[Hard AttacK]

My car is BPU with the stock fuel pump hotwired. (3 inch turbo back no mufflers/cats, intake, MBC, FULL vac reduction)

After hot wiring my fuel pump and deleting the fuel pump relay and the fuel pump resistor (http://www.stealth316.com/2-fuelpumprelaybypass.htm) because my car was running lean I seriously have the worst MPG ever. It's really hurting my wallet BAD. What could be the issue? Running too rich?

I have the chance to buy an AFC for a good price if that would help at all. I am going to log my car tonight in hopes that someone can tell me what's wrong.

A bad rear turbo wouldn't do this would it? Mine burns oil and is dying.

Any ideas? Thanks <3

[vr3.9]

sounds like your over running the stock fuel pressure regulator. Fuel trims are probably pegged rich and still not enough to compensate. Your still on stock turbos. I would just keep the wiring stock and maybe upgrade to a walbro. Or get a better FPR

[DocWalt]

Log it and post your logs. Sounds like either a bad O2 causing it to run super rich, or the FPR over-running. The FPRs are like any other part of the car and can cause issues.

[Hard AttacK]

Thanks!

Would lowering boost help?

[SpdDmnVR4]

unlikely... your not using the fuel your injectors are providing anyway, so lowering the boost would theoretically make it worse

[MADMarc]

Check that fpr. If that's the case, it shouldn't be an expensive fix and is a simple swap

[Hard AttacK]

how can i check it?

[DocWalt]

plumb in a fuel pressure gauge. I'd worry more about what your trims and O2s are doing to see if it's a dead O2 sensor, or if there's another underlying issue.

[GTOJOE]

A faulty AFM could also cause this couldn't it?

[x2xtreme360]

Do you have a logger? That would point to the issue real quick.

I don't see how it would be possible to be running lean, then hotwire the pump and see 5-10mpg due to overrunning the FPR. I hotwired my pump and saw a pressure increase, but I barely saw a change in my MPG. Something else is going on here.