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Discussion Starter · #1 ·
1991 S10 4.3 auto 4wd, I removed the bed a few months ago and power washed the frame, rear end, fuel tank, pretty much everything that was exposed and treated it with a rust convertor. Now I have crank, no start, but will start if primed and run until the primer fuel runs out. I don't hear the fuel pump turning on when I turn on the ignition. Just checked the ECM B fuse and it is good. Replaced the fuel pump relay on the firewall a few months before this issue started. Any ideas of where I should start checking/testing?
 

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Ground wire?
 

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The pressure from the power wash may have ruined a ground wire or possibly pushed a pin back in the plug. Check all connections with a test light and or a volt meter
 

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Discussion Starter · #4 ·
Thanks for the responses. I did take the ground wire loose from the frame earlier today and cleaned the bolt, frame and ground leads from the fuel pump, no help. I will check the plug and probe it with a test light.
 

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While you're probing, see if you have 12V on the grey or tan/wht wire. If you have that and a good ground it's the pump. If you don't have 12v at the connector with the key on and cranking it's forward of the pump. There is a test connector on the firewall that is a direct line to the pumps power wire. You can hook a jumper from the battery to test the pump. If it's grounded. The test connector looks like a single electrical connector not attached to anything.
 
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Discussion Starter · #7 ·
Tested 2 prong plug at the pump. One prong has 9.0V with key on, drops to 7.9V when cranking. No power to the other prong. Tested wire past plug on the pump side and same voltages. Ran 12v to test plug at firewall and still no pump sound and same 9.0V at plug near pump. Probed in 12.7V to the power wire, past the plug, at the pump with key on and still no pump sound. I figure this proves pump is bad. Should I be concerned about only 9.0V at the plug to the pump?
 

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Tested 2 prong plug at the pump. One prong has 9.0V with key on, drops to 7.9V when cranking. No power to the other prong. Tested wire past plug on the pump side and same voltages. Ran 12v to test plug at firewall and still no pump sound and same 9.0V at plug near pump. Probed in 12.7V to the power wire, past the plug, at the pump with key on and still no pump sound. I figure this proves pump is bad. Should I be concerned about only 9.0V at the plug to the u said that past the plug it tested 9v? did u probe ground too, or just your hot?
 

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Discussion Starter · #10 ·
Test light connected to battery positive and probed into wire through insulation past the plug at the the pump. Test light on when wire probed, so ground is good.
 

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Discussion Starter · #12 ·
I have not tried a different relay. Relay was replaced recently (prior to this issue) but I assume if the pump won't run with power to the test plug or power lead at the pump, and the ground is good, that it wouldn't matter if the relay was good or not?
 
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