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Fuel guage reads "0" after fuel pump swap- a few questions

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Old 01-11-2018, 06:41 PM   #1
qwiketz
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Default Fuel guage reads "0" after fuel pump swap- a few questions

Hi all,

I pulled my sending unit to swap fuel pumps. While I was at it I also replaced the wiring with new wiring from Racetronix. After reinstalling, the fuel gauge reads completely empty (no lines) even though there is a half tank. Would that indicate that the purple wire is broken/not connected? Or is this some type of ground issue? The gauge worked fine prior to this.

I used a butt connector and it appears to have an okay connection when setup but obviously something isn't right. I have the sending unit out of the car at this point and have inspected but didn't see anything obviously wrong. Thoughts?
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Old 01-11-2018, 10:19 PM   #2
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Hi all,

I pulled my sending unit to swap fuel pumps. While I was at it I also replaced the wiring with new wiring from Racetronix. After reinstalling, the fuel gauge reads completely empty (no lines) even though there is a half tank. Would that indicate that the purple wire is broken/not connected? Or is this some type of ground issue? The gauge worked fine prior to this.

I used a butt connector and it appears to have an okay connection when setup but obviously something isn't right. I have the sending unit out of the car at this point and have inspected but didn't see anything obviously wrong. Thoughts?
and sure enough with it out of the tank it works fine.... Time to try reinstalling it...
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Old 01-11-2018, 10:49 PM   #3
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I cant offer any advise, but I am about to swap my fuel pump and would like to hear what ended up being the cause of the malfunction.

I am also using the racetronix kit.

On a side note, did you swap pumps as an upgrade or was your pump failing?
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Old 01-11-2018, 11:15 PM   #4
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The restaurant escape is great but mine is a custom set up with a walbro 465 pump. Yours should be plug-and-play .

The weird thing with my sending unit is that when it's partially in the tank, the fuel level float works. When it is all the way and it goes completely to zero which is kind of the opposite of what I would expect to happen . If I push it too far I would kind of think that it would read artificially high
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Old 01-12-2018, 12:15 AM   #5
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When the fuel gauge indicates "0", that means the car (CCM) is seeing a low resistance or short to ground. Sounds like two points might be toughing as you move the unit around.

You might try disconnecting the power connector and connect an ohm meter across the fuel sending unit so you can monitor the resistance as you move it around. If all is good, check the power connector and wiring.
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Old 01-12-2018, 01:43 AM   #6
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Thanks! Got it figured out. There was a black wire on the outside of the sending unit that I was grounding causing the gauge to read zero. All is well now
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Old 01-13-2018, 05:27 PM   #7
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update....

so the gas gauge works now that the black wire outside the sending unit is not grounded. However the pump isn't working because now it's not grounded. I must have done something wrong here.

Last edited by qwiketz; 01-13-2018 at 05:29 PM.
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Old 01-14-2018, 10:32 AM   #8
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You may want to consider popping the pump out (you have done it a few times and see how easy it is) and rig up a "bench test" of some sort running wires and using the actual harness.

Yss, the purist freak when you lay the pump on your car, but the only (real way) to check the integrity of the WHOLE system is by testing the WHOLE system together. You simply just must "plug it in" to see if the fuel gauge, mote spins and ground work.

A bunch of alligator clips will be your friend.
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