Don Terrill’s Speed-Talk

ctk30 wrote: ↑Mon May 03, 2021 9:22 am...The pressure will drop free revving as well. Goes from 45 psi to 40-41, from the data log it seemed pretty steady at 40 psi under load driving.

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.)

NewbVetteGuy wrote: ↑Tue May 04, 2021 11:09 pm

2seater wrote: ↑Tue May 04, 2021 12:45 pm In many OEM installations the pressure regulation is actually downstream of the injectors

Sure but within a few inches to a couple of feet of the fuel rails, not like 14 feet, right? (Real question).


Adam

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.

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).

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

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

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

Realized when I wired in my volt meter I accidentally reversed it, so the pump wasn't pumping.

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.