78SC Firing but can’t Idle

[TargaWoods]

Rebuilding a barn find 78SC.

Replaced gas tank, fuel pump, fuel filter, injectors, spark plugs, new oil in it, sea foam in gas tank and oil tank.

Engine will turn over, but cannot maintain idle unless I press up on the air flow valve. When I press the valve, it idles fine, however when I’m doing that, the engine will die if I press accelerator.

Bosch Fuel pump has a massive whine to it when the car is running.

Fuel pump relay functions fine, right now, WUR, or a clog in the lines before or after the fuel pump are the main suspects.

Advice?

[shoooo32]

A bottle of techron is the dirty cheap answer. It's pretty great at removing varnish in CIS components.

The next step requires gages. Without knowing your fuel pressures, it's all a guess.

[David Inc.]

Well there's either not enough fuel or way too much air. If it's a new fuel pump it shouldn't be making so much noise unless it's fighting a restriction. Could also be a truly massive vacuum leak. Could be a bunch of stuff! In addition to what shoo said I'd check for vacuum leaks.

Easy to pick out the basic problem, but not enough to go on for many suggestions.

[EC900]

I’d wonder about the fuel accumulator if it wasn’t part of your replacement parts list, also if any adjustments were made to idle and the fuel regulator…which the mixture adj could have affect in cold idle air flow. Electronically, aux air regulator, cold start vale, thermo switch and relay…one can be bad or even became disconnected.
You got a barn find running that’s a good thing… old brittle vac lines and mice…oh boy.

W

[356911930]

There is also a screen filter on the top of the wur that could be clogged. Take the wur apart and inspect the screen.

Rahl