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93 GMC sierra pu wont start

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New User

Oct 6, 2005, 4:51 PM

Post #1 of 2 (3181 views)
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I have spark, plugs were dry, so now I'm looking toward the fuel system. It will occasionally start, I noticed that when it does start I can hear the fuel pump and when it won’t start, I don’t hear the fuel pump just prior to turning the key fully forward. My repair manual instructs me to perform testing, first with the fuel pump relay. Problem is, It’s not on the firewall within the engine compartment as indicated in the manual, Where is it? Also tried applying 12V to the fuel pump test connector pin however, no sound from the pump. Will the pump always run when 12V is applied to the test connector or once max pressure is reached the pump will not run any longer? Looking at the schematic of the fuel pump wiring diagram it appears applying 12v to the grey wire will make the pump run, will it?


Tom Greenleaf
Ultimate Carjunky / Moderator
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Oct 6, 2005, 6:59 PM

Post #2 of 2 (3174 views)
Re: 93 GMC sierra pu wont start Sign In

The owner's manuel should say where. If Not! buy the dang relay at GM and look at their screen for where. I'd start with the relay and then it's possible that you need a fuel pump. Good luck- T

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