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1990 fuel pump problems

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Old Oct 17, 2025 | 06:53 PM
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1990 fuel pump problems

I bought a 1990 bronco that someone else took apart and I’m trying to get it back together. I bought a new fuel tank and pump and installed it and can’t get the pump to work, I dropped the tank and disconnected the lines, While I’m under the truck my wife walked by and I asked her to turn the key on, She turned the key too far to the start position and the pump turned on and shut off as soon as she stopped trying to start it. It doesn’t operate in the on position. What could cause this? Bad ignition switch?
 
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Old Oct 17, 2025 | 07:56 PM
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From: Cedar Rapids, IA
Did that previous owner muck with the wiring? Another thought is you might have failed electrolytic capacitors in the ECM, but that typically results in the fuel pump priming and not shutting off versus not priming unless the key is on.

-Rod
 
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Old Oct 19, 2025 | 07:19 AM
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Originally Posted by Jkenosh
I bought a 1990 bronco that someone else took apart and I’m trying to get it back together. I bought a new fuel tank and pump and installed it and can’t get the pump to work, I dropped the tank and disconnected the lines, While I’m under the truck my wife walked by and I asked her to turn the key on, She turned the key too far to the start position and the pump turned on and shut off as soon as she stopped trying to start it. It doesn’t operate in the on position. What could cause this? Bad ignition switch?
It sounds like the engine didn’t start so there was no signal from the distributor to keep the pump on.
 
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Old Oct 19, 2025 | 12:08 PM
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It does start with starting fluid. As soon as it stops raining I will see what happens once it starts
 
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Old Oct 19, 2025 | 03:02 PM
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Does the pump stay running in the the RUN position if you jumper the terminals in the EEC self test connector?
 
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