Fuel Pump - Need Help, trying to fire up my barn find for first time...no fuel |
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Fuel Pump - Need Help, trying to fire up my barn find for first time...no fuel |
willimac |
Sep 14 2014, 07:48 PM
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#1
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Newbie Group: Members Posts: 14 Joined: 14-September 14 From: minnesota Member No.: 17,901 Region Association: None |
I'll try to keep the story short. I have a '74 1.8 L-jetronic 914 that I rescued from a barn in central Wisconsin almost 3 years ago. It had sat for over 20 years and become a palace for generations of barn mice, who built nests in every available cavity. Since then I've been sporadically cleaning it up, vacuuming mice and their nesting material, dropping the engine, dismantling and rebuilding it, cleaning up rust, shopping new parts (alternator, starter, stainless fuel lines, seals and gaskets) re-boring the cylinders, splicing chewed-through wiring, etc... finally got it put back together this week and am having trouble with the fuel delivery. The fuel pump does not turn on.
There is power to the double relay switch - terminal 86a checks out with the ignition switch on start, zeros out in "on" position , and AFM resistance checks out. The terminals at the fuel pump plug read zero volts unless the ignition is turned to "start" and the AFM is propped open - in which case it reads 7 - 8 volts. Don't know what to do---is there a way to test the pump to see if I need to replace it? Why would only 8 volts be making it to the terminals for the pump? Is this possibly a problem with the double relay switch? Any help would be greatly appreciated...I feel very close to bringing this one back from the dead. |
Dave_Darling |
Sep 16 2014, 12:28 PM
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#2
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914 Idiot Group: Members Posts: 14,991 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
Connect that jumper wire and measure voltage across the fuel pump wires. If it's +12V, that means the pump is getting power at that point and it not running is a defect in the pump. Probably gummed up with lacquer, as you said. You can clean them to some extent--the end cover is held on with four screws. Mark the end cover and the intermediate piece as well as the pump body so you can put it back together the same way it came apart, then you can remove the screws and clean up the rollers and rotor.
The rollers are little metal pucks, make sure not to lose them when you take the thing apart. If you can get them out (they're loose in there) and clean them and the rotor, then spin the rotor by hand, you'll at least have the mechanical parts of the pump freed up. I don't think the O-rings are available, but you can supposedly find fuel-compatible ones that fit. But it's best not to damage them if you can manage it. --DD |
willimac |
Sep 16 2014, 01:40 PM
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#3
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Newbie Group: Members Posts: 14 Joined: 14-September 14 From: minnesota Member No.: 17,901 Region Association: None |
Connect that jumper wire and measure voltage across the fuel pump wires. If it's +12V, that means the pump is getting power at that point and it not running is a defect in the pump. --DD Thanks for chiming in, Dave. Voltage at the pump is about 8 volts, decreasing the longer the engine cranks. I'm hoping that a full 12 volts (which it will hopefully get with the new double relay) will kick it into action. |
Dave_Darling |
Sep 16 2014, 06:25 PM
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#4
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914 Idiot Group: Members Posts: 14,991 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
Voltage at the pump is about 8 volts, decreasing the longer the engine cranks. I'm hoping that a full 12 volts (which it will hopefully get with the new double relay) will kick it into action. 8V should be more than enough to run the pump. I think yours is dead. --DD |
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