Fuel pump wiring

kenewagner

kenewagner

Registered User
I was finishing the fuel system today. Fuel Lines are all ran. I extended the wire that powered the Walbro pump back to the trunk hooked it into the racetronix wiring. With the car's key on I have power to the back. 9.6V. I expected that once wired into the harness it would trip the relay and give me 13V which is what the battery read. When I wired the old power wire into the harness it dropped to .25V and the main wire that should be powering the new pump had zero power. Dissconnect the wire from the harness and the reading is 9.6V. Having a hard time figuring this out.


Ken
 
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I would need to see a wiring diagram to figure out what youre doing ....

Unless your switched power is hooked up backwards on the relay.



- Dan
 
You should see VBAT (Battery Voltage) anytime you see any voltage. If you don't, something isn't right.
With key off, there should only be voltage at the battery connection of the racetronix relay. There should be no voltage anywhere else.

With Key on, the stock fuel pump relay should energize, putting VBAT at the line that normally goes to the fuel pump. I assume you have cut that line and extended it to be the SIGNAL wire for the Racetronix Harness. With VBAT there, the relay in the Racetronix harness should trip, which should allow the power from the fused connection on the racetronix harness to flow through to the fuel pump. it should be at VBAT.

It is important you don't try to make these connections neat and pretty. They need to be functional with good strong positive electrical connections. To trouble shoot I would disconnect battery power from the relay and just check and make sure you are geting VBAT on the signal wire to the relay.
Once you verify you have VBAT there and the relay is properly grounded, you should be able to verify it is switching by using your DVOM on the OHM setting and check the resistance between the big fused power cable (not connected to power) and the racetronix power output. The resistance should be 0. Turn the key off and it should be infinite.
Now connect the main harness but unplug the fuse. Tighten everything down and check for VBAT at the fuse block for the harness. Make sure you have VBAT on one side of the Fuse block and nothing on the other. Stick the fuse in and hook your meter up on the output that should go to the fuel pump. With the key off you should have 0V at the output to the pump. With the Key on you should see VBAT.
 
Mike8675309 said:
You should see VBAT (Battery Voltage) anytime you see any voltage. If you don't, something isn't right.
With key off, there should only be voltage at the battery connection of the racetronix relay. There should be no voltage anywhere else.

With Key on, the stock fuel pump relay should energize, putting VBAT at the line that normally goes to the fuel pump. I assume you have cut that line and extended it to be the SIGNAL wire for the Racetronix Harness. With VBAT there, the relay in the Racetronix harness should trip, which should allow the power from the fused connection on the racetronix harness to flow through to the fuel pump. it should be at VBAT.

It is important you don't try to make these connections neat and pretty. They need to be functional with good strong positive electrical connections. To trouble shoot I would disconnect battery power from the relay and just check and make sure you are geting VBAT on the signal wire to the relay.
Once you verify you have VBAT there and the relay is properly grounded, you should be able to verify it is switching by using your DVOM on the OHM setting and check the resistance between the big fused power cable (not connected to power) and the racetronix power output. The resistance should be 0. Turn the key off and it should be infinite.
Now connect the main harness but unplug the fuse. Tighten everything down and check for VBAT at the fuse block for the harness. Make sure you have VBAT on one side of the Fuse block and nothing on the other. Stick the fuse in and hook your meter up on the output that should go to the fuel pump. With the key off you should have 0V at the output to the pump. With the Key on you should see VBAT.
Click to expand...

I dont have the power wire hooked to the pump yet. Am just looking for power there
. I will check it out as you have outlined. Wiring is not my strong suit

ken
 
Well where you are at, you should see VBAT at the wire that comes off the stock power relay.You could check it at the fuel pump relay, and then again at the wire going to the fuel pump. Should be about the same voltage at both places.

With no power to the racetronix harness, there should be no voltage on the racetronix wire to the fuel pump.
 
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