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 |
swl |
May 20 2010, 05:44 AM
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#2
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
ah yes the aux air regulator! It runs off the same fuse as the fuel pump and would be drawing current even when the car is not running. (as would the heater fan and the rear window defogger). Clay is right - it could be on the delivery side of the relay.
In all of this have you replaced the fuse on the relay board? This may well be completely unrelated to the first problem of a bad relay. Just before my car went down for the big sleep I had a problem identical to this - fuel pump cutting out after a while and then coming back to life. It turned out to be the fuse. It had not blown - that would be too easy to spot. But internally the connector was loose and when hot would separate from the end piece. when it cooled down it would make contact again. |
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