Car Running Rich/Too Much Fuel Pressure

[Laffs]

This seemed to start around the time I installed my new non leaking corrugated fuel line but can't say it was a 1:1 cause/effect.

Stock 2v fuel system aside from a 340LPH pump in the factory basket. No BAP/modified FPDM. Car is Vortech supercharged, 39lbs injectors and lightning MAF. No changes made to tune before problem occurred.

My STFT are basically pegged at 1.25 under idle and cruising and fuel rail pressure is reported at 58psi. Under wide open throttle it levels out to a STFT of .8-.9 and rail pressure of 44psi until I max the duty cycle of the pump and pressure fails (separate issue I believe).

[ZR]

- you've confirmed it's a return less pump?

- I don't recall for sure on the '04 n older, '05 up same scenario if ground wire from fpdm is pinched between it and the pump, commands full output from the pump.

- If answer to above is yes fpdm controls ground side, check to be sure there is not a second source of ground inside the hat / module itself. We've now had two mis made '05 up drop in modules with an internal ground that should not have been there.

- disconnect MAF n see if fuel pressure drops. Odd part, some will run with it disconnected and some won't, have seen one with a MAF issue experience high fuel pressure.

[Laffs]

- you've confirmed it's a return less pump?

Yes, at least it was sold to me as such originally in 2012

- I don't recall for sure on the '04 n older, '05 up same scenario if ground wire from fpdm is pinched between it and the pump, commands full output from the pump.

This is something I should check, I think I had a wire caught in the hat before

- If answer to above is yes fpdm controls ground side, check to be sure there is not a second source of ground inside the hat / module itself. We've now had two mis made '05 up drop in modules with an internal ground that should not have been there.

Its the factory wiring spliced in I beleive, same as its been since 2012, don't think any wiring has changed.

- disconnect MAF n see if fuel pressure drops. Odd part, some will run with it disconnected and some won't, have seen one with a MAF issue experience high fuel pressure.

Will do sir, thanks




Replied above, thank you for the insights.

[ZR]

Replied above, thank you for the insights.

If it comes down to pulling the tank down, pull numbers off the pump n double check.

Factory wire spliced in, explain?

[Laffs]

Pump came with two wire harness, that was spliced in to the power/ground supply left from the factory pump.

[ZR]

Roger that.

[Laffs]

I'm going to try and get the tank down to a 1/4 at some point and drop/inspect. If the wire is pinched would it still make sense the pressure does drop eventually once wide open throttle occurs?

[ZR]

We've seen more than one '05 with a pinched ground triggering full pump output where pressure did get much closer to normal but only at times. Ones that pissed me off to no end, new unit with an internal ground causing us to go nutz for more hours vs I'd like to admit.

[ZR]

If you drop the tank, also a good idea to confirm neg wire is not chaffed / grounded where it comes through the hat itself.

[Laffs]

Sounds like a good plan of attack.

[Monera3v]

To confirm you have a runaway fuel pump.
Key on, Do not start.
If you hear the pump keep priming and running. More likely it shorted! Internally or externally via harness!
@_@ yes I ripped my hair out figuring out why My fuel pump pegged my fuel pressure sensor for 3 weeks, only to found out my return and ground had rubbed against the tank.

[Laffs]

Key on with gauge on reg it builds 40psi and stops, doesnt keep building, if that matters.

[Laffs]

Still doing this shit, calgone take me away.

[Ponyryd]

Does this year have a fuel rail pressure sensor, is it bypassed in the tune?

[ZR]

^ If unplugged, what happens to fuel pressure?
Is sensor hooked to a proper vac source (low vac = higher pressure)?

[ZR]

What are results of questions pg 1?

[ZR]

If all the above are ok / pump confirmed etc, you have access to a test FPDM?

[Armen]

Still doing this shit, calgone take me away.

Bill Aitken can take away all your problems.

[Laffs]

MAF doesnt make a change. Confirmed no pinched wires.