Fuel Pump Diagnostics |
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Fuel Pump Diagnostics |
solex |
Mar 21 2010, 12:40 PM
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#1
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Senior Member Group: Members Posts: 789 Joined: 12-January 05 From: Long Island, NY Member No.: 3,439 Region Association: North East States |
Hi All,
Need a little help to diagnose a fuel pump problem in a 75, I do not hear the pump when I turn the key to the run position. The car was running, I had a few occasions where it would not start, let it sit for a few days and it was start right up. The grounds: under the relay board, battery and transmission have all been cleaned. All fuses are good. The relay is working as I can hear it click into position. When the key is in the run position relay terminals 30 and 85 shows 12 volts. Terminal 86 show 0.03 volts and terminal 87 show zero volts. There is no voltage at either of the fuel pump terminals. The readings at the relay is counter to to what Haynes states (86 should read 12 and 85 should be ground). I not sure where to check next, really do not want to pull the tank. Any assistance would be appreciated. Thanks, Dan |
Katmanken |
Mar 21 2010, 08:29 PM
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#2
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You haven't seen me if anybody asks... Group: Members Posts: 4,738 Joined: 14-June 03 From: USA Member No.: 819 Region Association: Upper MidWest |
Most VOM's have a continuity checker that beeps when both VOM leads are shorted together. Turn the VOM to continuity, contact the brown wire going to the pump with one lead, and touch a bare part of the chassis. If it's grounded, it will beep or buzz
Try the same check on the other wire to the pump. If it buzzes too, there is your problem wire. You are going to have to trace the wiring from the pump to the dash. I have 2 1974's and no front pump wiring on the harnesses. But since I swapped harnesses, there is a part of my harness that extends from the fusebox area into the front trunk area. Some of it goes to the right to connect to the sender on the top of the fuel tank, the wipers, and the blower box. I'd look around there for wires to the pump or maybe on the left side of the depression that holds the fuel tank. Note the wire color(s) and size on the pump wires and look for a match. Brown is always ground. Have a circuit diagram for a 1975? It should show where the pump wires attach. |
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