The fuel demand when free-revving is negligible; it wouldn't be enough for the car to even move, so maybe engine vibrations are triggering resonance in an electrical connection or some defective part in the regulator. You should check the voltage at the pump with the engine running, then if OK, do a flow test into a container. (Check the pressure at the same time.)
EFI Fuel Pressure Drop ~5psi
Moderator: Team
Re: EFI Fuel Pressure Drop ~5psi
Felix, qui potuit rerum cognscere causas.
Happy is he who can discover the cause of things.
Happy is he who can discover the cause of things.
Re: EFI Fuel Pressure Drop ~5psi
Yes, at or near the fuel rail, but on the return to tank. The regulator should be referenced to the intake manifold vacuum/boost if port injected but not certain about a TBI type installation and would consult their installation instructions.NewbVetteGuy wrote: ↑Tue May 04, 2021 11:09 pmSure but within a few inches to a couple of feet of the fuel rails, not like 14 feet, right? (Real question).
Adam
-
- Expert
- Posts: 858
- Joined: Sun Nov 04, 2007 8:47 pm
- Location: Corona, CA
- Contact:
Re: EFI Fuel Pressure Drop ~5psi
Are you running a dead-headed line to the front from the rear regulator? That will cause the pressure drop, especially if you also have a fuel filter that is getting clogged.
If you're running pump -> filter -> injection -> regulator -> return to tank, then you wouldn't have this problem unless the pump or filter is bad.
I'm guessing you're running Pump -> regulator + return to tank -> dead-head line with filter to the front. This will dip as the filter slowly clogs or with lots of bends or with just high flowrates on a smallish fuel line.
If you're running vacuum reference to the regulator, the pressure will dip with vacuum, but should be near the set pressure during full throttle (unless your filter is getting clogged).
If you're running pump -> filter -> injection -> regulator -> return to tank, then you wouldn't have this problem unless the pump or filter is bad.
I'm guessing you're running Pump -> regulator + return to tank -> dead-head line with filter to the front. This will dip as the filter slowly clogs or with lots of bends or with just high flowrates on a smallish fuel line.
If you're running vacuum reference to the regulator, the pressure will dip with vacuum, but should be near the set pressure during full throttle (unless your filter is getting clogged).
Re: EFI Fuel Pressure Drop ~5psi
The only fittings are straight fittings at the tbi and 90 at the fuel cell. The lines are 6an Teflon. Didn’t measure lines but it’s something like 14-15 for each
The system goes
Pump > filter > injectors > regulator > return
I can retest the pump with it running.
Thinking about taking out the element and testing as well. Not sure if the injectors could get clogged from that in a short period though
The system goes
Pump > filter > injectors > regulator > return
I can retest the pump with it running.
Thinking about taking out the element and testing as well. Not sure if the injectors could get clogged from that in a short period though
k1ob.com
Re: EFI Fuel Pressure Drop ~5psi
Well I think I figured it out. I bumped the regualator up to 60 psi and it seems like it doesn't pump fuel anymore.
I can hear the pump kick on and the holely dash says 0psi and I don't hear any fuel moving
I'm assuming the tube from the pump to fill plate has come apart
I can hear the pump kick on and the holely dash says 0psi and I don't hear any fuel moving
I'm assuming the tube from the pump to fill plate has come apart
k1ob.com
Re: EFI Fuel Pressure Drop ~5psi
Realized when I wired in my volt meter I accidentally reversed it, so the pump wasn't pumping.ctk30 wrote: ↑Fri May 07, 2021 7:04 pm Well I think I figured it out. I bumped the regualator up to 60 psi and it seems like it doesn't pump fuel anymore.
I can hear the pump kick on and the holely dash says 0psi and I don't hear any fuel moving
I'm assuming the tube from the pump to fill plate has come apart
Voltage seemed good at the pump while running. The test wires did get pretty warm and the connectors. When it was removed though the wires didn't seem to get warm.
I think next up is a new fuel filter and moving the regulator to the front. Might just try to fuel filter first since its easiest.
k1ob.com