Replacement Fuel Pump failed in 3 seconds

Gotta love that wiring . . .
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nick2110
Posts: 3
Joined: Tue Nov 22, 2022 7:53 pm
Your car is a: 1981 Spider Turbo

Replacement Fuel Pump failed in 3 seconds

Post by nick2110 »

I replaced the fuel pump in my 1981 spider and I tested it using the AFM flap and it buzzed for about 3 seconds then quit. I would love any suggestions to diagnosing the problem.

Backstory: The car has been driving great all summer, until the fuel line started to leak at the point just after the fuel filter. I barley made it home before the tank was empty and the car ran out of fuel. I replaced the fuel line, added 2 gal of gas and it wont start. I then cycled the AFM flap and the old fuel pump wouldn't buzz, so today I replaced the pump. While I had the old fuel pump disconnected, only about 1/2 cup of fuel came out of the tank line before flow stopped. Once installed, I moved the flap and the pump buzzed for about 3 seconds before going silent. I checked the fuses in the box as well as 2 inline fuses, which all seem fine. Neither of these matched the description of white wire/ red holder I've seen elsewhere.
Now I'm stumped on how this new pump failed almost instantly.

A few things I am considering might have happened:
-There is a blockage of fuel in the tank/line and no fuel can reach the pump. Would this have burnt up the new pump?
-Sediment was sucked into the fuel lines when the fuel level reached empty, killing the old fuel pump and new one.
-The fuel filter is full of junk and therefore the pump wont activate
-Something electrical (fuses, relays) that I wasn't able to check

I saw recommendations to put a fuel filter before the pump but I replaced the tank about a year ago so I didn't think it would need an extra filter.
spider2081
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Joined: Fri Jan 27, 2006 11:45 pm
Your car is a: 1981 Spider 2000
Location: Wallingford,CT

Re: Replacement Fuel Pump failed in 3 seconds

Post by spider2081 »

Have you measured voltage at the fuel pump connections? With the AFM vane opened the fuel pump should have battery voltage across the pumps terminals. I also like to measure the voltage on the green/black wire to ground in care the ground is bad. The ground is made in the trunk on one of the driver side tail mounting studs.
nick2110
Posts: 3
Joined: Tue Nov 22, 2022 7:53 pm
Your car is a: 1981 Spider Turbo

Re: Replacement Fuel Pump failed in 3 seconds

Post by nick2110 »

Yes the fuel pump is getting power, I checked that positive and negative are on the correct terminals. That battery is sitting at 12.6v and the pump is receiving 10.6v when the air flap is open and ignition on. I also tried giving the pump a few wacks to get it moving with no success.
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Replacement Fuel Pump failed in 3 seconds

Post by 18Fiatsandcounting »

If the fuel pump is getting power, then I think we're back to your first thoughts about gunk in the tank/lines/filter, and this possibly jammed the pump. One trick is to put the inlet hose of the fuel pump directly into a small container of clean gas, and see if it will pump that. Bypass the tank, filter, etc.

10.6V at the pump should turn it on, but I don't know electric fuel pumps all that well. Perhaps connect the power lead directly to the 12.6V battery with a jumper wire and see if the pump comes on. If there is nothing, then it appears the pump is dead but I would check the ground for the pump as well

-Bryan
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ORFORD2004
Posts: 1120
Joined: Wed Mar 17, 2010 9:48 pm
Your car is a: 1983 PININFARINA
Location: Sherbrooke, Qc, Canada

Re: Replacement Fuel Pump failed in 3 seconds

Post by ORFORD2004 »

Did you run the pump dry?
spider2081
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Posts: 3015
Joined: Fri Jan 27, 2006 11:45 pm
Your car is a: 1981 Spider 2000
Location: Wallingford,CT

Re: Replacement Fuel Pump failed in 3 seconds

Post by spider2081 »

Yes the fuel pump is getting power,
Just curious did you have the meters black lead on ground or on the pumps negative terminal when you tested for power.
Also 10.6 volts is low, I would expect something closer to 12 volts. The fuel pump ground is usually made at the driver side tail light. One of the tail lights mounting studs has the white black fuel pump ground wire and the tail light ground wire being made on the stud. Usually the ground is iffy as the paint was not removed during installation.
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