1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Help-1983 S2 No Fuel Pump Power

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Old Aug 13, 2019 | 08:13 AM
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Help-1983 S2 No Fuel Pump Power

Hi, I've been restoring a 1983 for almost a year now and am working on the interior. After a carpet install and a combo switch (turn signals/lights) replacement my fuel pump quit, I don't think I disconnected any wiring accidentally and I did check all visible connectors and from what I can tell the power supply doesn't run through the combo switch. I checked for power at the fuel pump connector under the storage box it had no power, Then I checked the fuse its good but the fuse is not getting power at the box. From what I can tell the S2 doesn't have a fuel pump relay like the S3 does. After looking at the wiring diagram I'm thinking ignition switch. Has anyone had this problem or have any advice? Thank You.

Last edited by Lews83GS; Aug 13, 2019 at 08:14 AM. Reason: misspelling
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Old Aug 13, 2019 | 09:20 AM
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Are you getting 12V to the pump connector when the engine is cranking over? Have you attempted to apply 12V direct to the pump connector to determine if it can be powered with direct power?
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Old Aug 13, 2019 | 01:31 PM
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Originally Posted by mazdaverx713b
Are you getting 12V to the pump connector when the engine is cranking over? Have you attempted to apply 12V direct to the pump connector to determine if it can be powered with direct power?
I've checked the pump connector, no power. I'm thinking I need to try the direct 12v power as you suggest. I've read several post where they just bypassed the original wiring, just trying to decide what it should be connected to.
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Old Aug 13, 2019 | 04:52 PM
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From: KC
Use the schematic to trace the 12v source back till you get it. You might need to be cranking to get the 12v to the pump.
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Old Aug 13, 2019 | 11:23 PM
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Originally Posted by KansasCityREPU
Use the schematic to trace the 12v source back till you get it. You might need to be cranking to get the 12v to the pump.
Thank you for the idea, I used the schematic and figured out the ignition switch was good and had power to the fuse box, but could not find power coming back from the pump. I went ahead and ran a new switched 12v source with 10 amp fuse to the pump and have it working. I'm not sure what happened to the original power supply, that will have to wait until another day.
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Old Aug 14, 2019 | 05:42 AM
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You may find that you have a small break in one of the wires in the harness that feeds power to the fuel pump. It's a short routing honestly. You'll have to remove the driver's seat and pull the carpet up to expose the harness. Will lead you right to the pump under the storage bin frame from the fuse panel. Should be able to see if any wiring was chewed by a rodent or if something was flexing where it shouldn't and ruined through the harness and caused an open in the circuit.
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Old Aug 16, 2019 | 08:45 AM
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Glad to hear you got it sorted! As mazdaverx713b said, could be a small wiring issue that crept up over time (like chafing or wear) that will be difficult to track down. What matters is that for now your car runs!
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Old Aug 16, 2019 | 09:12 AM
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From: KC
Originally Posted by mazdaverx713b
You may find that you have a small break in one of the wires in the harness that feeds power to the fuel pump. It's a short routing honestly. You'll have to remove the driver's seat and pull the carpet up to expose the harness. Will lead you right to the pump under the storage bin frame from the fuse panel. Should be able to see if any wiring was chewed by a rodent or if something was flexing where it shouldn't and ruined through the harness and caused an open in the circuit.
This is a very good point. Running a new 12v source is a good way to verify that everything after that connection is good. The gotcha is that if the original wire is compromised, it could over time create a short and blow fuses. Hunting it down after a new 12v source has been ran makes it harder.
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Old Aug 16, 2019 | 10:19 AM
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Strongly suggest looking for the true root cause, then fix it.

We've all had to deal with issues from prior owners that half-fixed things that make it difficult to know what's going on. One of the big benefits of the FSM and the knowledge on his board is that if it's in factory configuration, someone can tell you how to fix it from a thousand miles away.

Start plugging crap together, bypassing factory wiring, and you're on your own from that point forward. I learned this while troubleshooting my SE short that turned out to be the Bypass Air Control Valve harness shorting against the solenoid body, when I thought it was the Fuel Pump Relay - not even close in proximity.

Put some additional effort to find the root cause and you'll be thanking yourself later, and will retain confidence in the vehicle. Every workaround kills confidence when stuff breaks or stops working...
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