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02-15-2018, 01:04 PM
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#1 |
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Registered User
Join Date: Dec 2011
Location: Boise, Idaho
Posts: 594
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fuel pump relays
Hello,
1989 v2500 5.7. Can someone walk me though trouble shooting my fuel relays. I have wire diagrams but just can not figure out an easy way to test. My truck runs fine but every first start of the day it has to crank. I believe the "start relay" is not working and I am not getting fuel pressure until I have oil pressure. What i have read is there is a second relay that primes for a few seconds but stops and then the oil pressure/fuel takes over. I think the prime relay is not working. My pump is so quiet i can not hear it run. If someone can simplify this circuit at the firewall it would be a great help. Chris |
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02-15-2018, 02:29 PM
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#2 |
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Senior Member
  Join Date: Oct 2014
Location: Eagle, ID
Posts: 3,068
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Re: fuel pump relays
Here's a link on how to test a relay, if that's what you are asking. http://www.learningaboutelectronics....o-test-a-relay
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02-15-2018, 04:40 PM
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#3 |
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Registered User
Join Date: Aug 2012
Location: Oklahoma City, OK
Posts: 2,620
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Re: fuel pump relays
Quick test is have a helper turn the key to run but not start, while you have an ear next to the relays. You should be able to hear the prime relay click. No click could be bad relay or bad magic timing gizmo that makes it run for x number of seconds when ignition is turned on. If you hear a click but no fuel pressure, probably a bad set of relay contacts.
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