Bad VAF? Fuel pump not working unless connector jumped

[RXFORYOUR7]

Long story short, fuel pump doesnt work unless the test connector is jumped. Once its jumped, it works great. Bad VAF or relay? I hear the relay clicking when the test connector is jumped so I thought it should be good.

Any specs to testing the VAF? I didnt see anything in the Haynes manual.

[sam.1956]

The test connector jumper just bypasses the VAF "door open" switch, correct? If the fuel pump produces pressure when the VAF door switch is bypassed, then the pump's relay, motor & the remainder of the circuit incl. the inertia switch would be functional.

[RXFORYOUR7]

The test connector jumper just bypasses the VAF "door open" switch, correct? If the fuel pump produces pressure when the VAF door switch is bypassed, then the pump's relay, motor & the remainder of the circuit incl. the inertia switch would be functional.

So what you're saying is if the fuel pump test connector is jumped and fuel comes out of the pump then the fuel pump relay is good?

I was under the impression this fuel pump test connector bypassed the relay?

I found the small section in the haynes manual about testing the VAF signal. Using two different multimeters (old analog and new digital) I recieved NO voltage on the first two pins which should be voltage and ground from left to right. I believe the manual said I should recieve a 12v signal. This was tested with the key switched to on position.

I did recieve 5v and 7v from some of the other pins.

[sam.1956]

Trying to go from memory w/o the benefit of a schematic in front of me!

IF all the test connector jumper does is bypass the VAF door switch, then yes the relay has to be OK else the pump couldn't turn on. If however the jumper bypasses the relay altogether & applies power directly to the pump motor, then the problem still could be the relay and/or the VAF door switch.

[RXFORYOUR7]

Trying to go from memory w/o the benefit of a schematic in front of me!

IF all the test connector jumper does is bypass the VAF door switch, then yes the relay has to be OK else the pump couldn't turn on. If however the jumper bypasses the relay altogether & applies power directly to the pump motor, then the problem still could be the relay and/or the VAF door switch.

Going over some old posts it seems as though the test connector energizes the pump relay if I read it correctly so I think you were right the first time.

Where do I go from here? No 12+ at the VAF connector but the fuel pump turns on when the test connector is jumped.

[SIBladerunner]

Make sure that when you are cranking the engine that there is Bat Voltage at the pump wires leading into the VAF. If there is no voltage the VAF is not telling the fuel pump to turn on. The relay is good cause you can hear it clicking. and the pump is good cause you said you can run the engine just fine. I have a VAF that I can sell you for $30shipped and it came out of a working B3 engine. Let me know if you're interested.

[Damkid]

If you have a spare relay in a different festiva, try swapping it out, it'd be a quick and cheap way to test it

[RXFORYOUR7]

Fuel pump does NOT work when engine is cranked but does work when the test connector is jumped and the key is in the ON position.

So, relay is good and pump is good. I've narrowed it down to the VAF or the damn tank and fuel pump assembly being rusty enough its not grounding out.

I may be looking to buy that working VAF from you SIBladerunner. Anyone have a not to rusty fuel pump assembly?

[RXFORYOUR7]

Forgot to mention, my fuel gauge reads empty even though theres gas in the tank.

[festivaWES]

that just means the rheostate is faulty, doesn't necisarly (sp) mean the pump is bad. Have you tried the roll over swtich under the driver side speaker panel?

[FB71]

ok, the test connect ONLY bypasses the switch in the VAF. If shorting the test connector causes the fuel pump to run, and the car starts and runs, then the fault is in the VAF or VAF wiring ONLY. The fuel pump, inertia switch, FP relay are all good if the pump runs. If the car starts and runs, then the tank/pump are clear, and not clogged with rust or dirt. More than likely, the VAF is the problem.

[FB71]

oh, and the fuel pump DOES NOT use chassis ground in the fuel tank. It has a dedicated ground in it's wiring harness. Rust on the pump assembly will not cause electrical problems. Also, as was said, the sending unit is electrically separate from the pump circuits.

[RXFORYOUR7]

oh, and the fuel pump DOES NOT use chassis ground in the fuel tank. It has a dedicated ground in it's wiring harness. Rust on the pump assembly will not cause electrical problems. Also, as was said, the sending unit is electrically separate from the pump circuits.

Thanks for the excellent info, Jim. The inertia switch is depressed so that shouldnt be the problem. Looks like it should be the VAF then.

Should I try starting the car with the fuel pump test relay jumped? I had the hose disconnected from the rail so I could see if fuel was coming out, I didnt even attempt to connect it and start it.

[SIBladerunner]

Well all I can tell you is that I feel since you can get everything to work that its just the VAF not commanding the pump to go on. Cause if you jump the test connector and get the pump to run, you know that the pump can ground out.

Did you check for bat voltage at the pump wires on the VAF WHILE CRANKING?

[RXFORYOUR7]

Well all I can tell you is that I feel since you can get everything to work that its just the VAF not commanding the pump to go on. Cause if you jump the test connector and get the pump to run, you know that the pump can ground out.

Did you check for bat voltage at the pump wires on the VAF WHILE CRANKING?

Naw I sure didnt SI. I did it while the key was in the ON position and got the reference voltage of 5.9 on the last two pins but my first two pins didnt show a 12v current.