2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Fuel pump electrical problem

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Old Sep 6, 2019 | 06:45 PM
  #1  
docbong85's Avatar
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Joined: Aug 2019
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From: Cranbrook, BC
Fuel pump electrical problem

need some help diagnosing a problem before i buy a new pump.
engine doesnt start, and was flooding.
so i did a compression check, spark check, and then was about to do a fuel pressure check.
i plugged in the yellow test connector jumper to run pump, reinstalled egi comp fuse, and made sure pump cutoff switch was back to ON position after depressurizing to install gauge. Turned key to ON position, and pump isnt coming on.
i checked that the yellow test connector is reading 12v, so its not that circuit. Then i checked pins on pump connector in the trunk.
This is where it gets weird.
on the blue wire im getting steady 1.15v, red im getting a bouncing reading that cycles like this: 12v-8v-3v-4v-6v-7v......., and the last pin reads zilch. The weird part is, i get these readings regardless if the yellow jumper is connected or not. (Hence why i ended up testing the jumper to make sure it was actually getting power, and didnt have a bad wire or something)
To clarify a little, i just put this engine back together after being partially apart for quite a while, and 4 days ago was able to pressurize system using the jumper. (Hence how i got the point of trying to start it)
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Old Sep 16, 2019 | 07:34 AM
  #2  
fc nut's Avatar
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Joined: Oct 2008
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From: ohio
Originally Posted by docbong85
need some help diagnosing a problem before i buy a new pump.
engine doesnt start, and was flooding.
so i did a compression check, spark check, and then was about to do a fuel pressure check.
i plugged in the yellow test connector jumper to run pump, reinstalled egi comp fuse, and made sure pump cutoff switch was back to ON position after depressurizing to install gauge. Turned key to ON position, and pump isnt coming on.
i checked that the yellow test connector is reading 12v, so its not that circuit. Then i checked pins on pump connector in the trunk.
This is where it gets weird.
on the blue wire im getting steady 1.15v, red im getting a bouncing reading that cycles like this: 12v-8v-3v-4v-6v-7v......., and the last pin reads zilch. The weird part is, i get these readings regardless if the yellow jumper is connected or not. (Hence why i ended up testing the jumper to make sure it was actually getting power, and didnt have a bad wire or something)
To clarify a little, i just put this engine back together after being partially apart for quite a while, and 4 days ago was able to pressurize system using the jumper. (Hence how i got the point of trying to start it)

The red and blue wires go to the fuel gauge and the warning light. The black/white stripe wire is power, the other black wire is ground.
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