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 |
solex |
May 16 2010, 08:42 PM
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#2
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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 |
Quick update. I connected a DVM to the pump and turned the key to the start position. As expected the voltage went to 12V and the pump circulated for 1.5 seconds and then stopped and the voltage also went to zero. I did this several times with the same result.
I mistakenly left the key in the on position for a good 5 minutes. After which I turn the car off and turned the key back to the run position: No re-circulation No voltage This is the exact condition that I have every time I was stranded. The car will not start, but if I leave it I bet it will start tomorrow or later tonight. BTW I can hear the relay click (I know this is not indicative). You guys think it is still the pump? |
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