fuel pump issues

Got back last night after 2 weeks and the car won't start. Trouble shooting found the following conditions:

Battery is good

New Relay

Fuse good

Fuel pump makes a "taser" (fast click,click, click) sound instead of "whirring"

Voltage at the tank connection does not go above 4v on the multi-meter during pump priming.

Ground inside rear quarter is good.


What am I missing?

You should have battery voltage at the pump. Did you check it when it was unplugged? You may have a bad connection at some point in the wiring. I suggest that you check for resistance at all connectors, and wire to pin connections. If you have a rusty chassis, the ground may not be as good as a rust free one. I believe the initial path uses the oil pressure switch to hold the circuit, then switches to the relay.

the 4 volts MAY have been a bad connection with the multi-meter. picking up alligator clips today so I have a better connection.

Also ordered the spectra SP127B1H assembly last night. The 128 is for the sedan and the 127 has a longer connection wire for the wagon.

OK, was draining the tank and thought to myself "why not try again.."

She started. Pressure gauge read 0psi until I turned the key. Jumped to 20psi and started.. she wasn't happy, but ran. Blip the go pedal and psi drops to 5psi. Let her warm up and psi tops out at 24psi.
Run the RPMs up slowly and psi remains at 24, do it fast and it drops by 12-15psi.


I have always thought that the pump is either on or off. Is this a correct assumption?

Is this a filter or regulator issue? Filter is cheap but the regulator is not @ $70

Filter would not explain the 0psi, not sure about the regulator.

Sounds like the pump to me. I had the same behaviour on my old 92 before the pump finally died.

Krzdimond wrote:

OK, was draining the tank and thought to myself "why not try again.."

She started. Pressure gauge read 0psi until I turned the key. Jumped to 20psi and started.. she wasn't happy, but ran. Blip the go pedal and psi drops to 5psi. Let her warm up and psi tops out at 24psi.
Run the RPMs up slowly and psi remains at 24, do it fast and it drops by 12-15psi.


I have always thought that the pump is either on or off. Is this a correct assumption?

Is this a filter or regulator issue? Filter is cheap but the regulator is not @ $70

Filter would not explain the 0psi, not sure about the regulator.

I'm not familiar with the LT1, but does the Optispark system use an ignition control module? Thats what caused my car to have bad fuel pressure until I replaced it a few weeks ago. Also, check the sending unit for damaged/corroded lines. Mine had a pinhole leak which I think was the root of my issues last winter.

Also, an LT1 fuel pressure regulator is $40 from Rockauto. Delphi part number FP10004

Rock auto is not an option. I can get it tonight from autozone and be on the road tomorrow...

I already told you what I think earlier today. Throw the spare used pump in there and see what's up.

You have a young able bodied son to help you, just use my method to drop the tank with the jack and the fact it's full isn't as big of a deal....it's not a bad job to drop it.

I agree with sprocket, swap the pump. The running pressure is low. Yes, it is either on or off, so if the pressure is not up to spec, and you have a pump, you should try swapping to get off on the cheap. If it has the same symptoms after swapping the pump, then is is probably the regulator.

I dropped the tank on mine by removing the fuel lines, rear bolts, loosening the front bolts, and sliding it down the straps, and out to the rear. Remove the filler neck at the bottom, and put a pan/bucket under the hose to catch any gas. You may be able to syphon the gas from the output tube from the pump. You could even use the pump to remove the gas. It does run.

new pump. 24psi is too weak,.

nick

so what happened?

Looked for a new van today. Take delivery tomorrow night. Wagon on back burner until NEW pump arrives on Thursday. No sense in doing it twice.... not even sure the used pump is any good after bouncing around in the cubby hole for 6 years I will update after the R&R.

New filter installed today with limited improvement.