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 23 2010, 08:19 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 |
Today I decided to check the fuses based on Matt response and realized after checking the manual I should have 8 AMP and 25 AMP (fuel pump) fuses. The PO had been running 16 AMPS in both slots so never thought to check.
I was able to start it today and run it for a while but after I would shut it down it would not start. I checked the power at the pump and it was getting close to 11 Volts, put a charger on start mode and it was getting close to 12 (not certain if the voltage should have been close to 12 and want to be sure). The 1.5 second voltage recirculation was happening but no pump action. I also jumped 30 and the 87 pin and had constant voltage at the pump. I even tried removing AAR out of the loop and still could not get the pump to recirculate even though there was voltage, so I'm certain now that the pump is the problem. I will order a new one and will report back |
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