Confused, I need help on different fuel pump wiring methods.

79Stang351W · 10-07-2004, 05:46 PM

On my carbed 79 Coupe with 351W, I ran a Mallory Comp 140 with 1/2 in. lines and a 1/2 in. return. I used a Radio Shack 30 amp relay. I also picked up a socket that fits onto the relay with wires for splicing into. I mounted the relay inside the trunk on the spare tire well. I drilled a hole in the sparetire well to put the wires through and put a rubber grommet in the hole to protect the wires. I used 10 gauge wire for power supply and ground, and 12 guage for the switch. Anywho, on the specific relay I used, Radio shack 30 amp, connect as follows:

86 - power switch: 12 guage wire to your on/off switch (You can connect into your ingnition switch wires, but I just used a 30 amp double pull on/off switch and ran it to the battery connection on the solenoid. I wanted to be able to shut off the pump and let the engine run to drain the bowls for jet changes.) Note: I also used an inline cylinder type 7.5 amp fuse for this switch.

85 - Ground. 10 guage wire to frame in rear. Two wires, ground wire from the relay and ground from the pump connected to the ten guage wire then to the frame.

87 - Power: 10 guage wire from positive side of battery with heavy duty cylinder type fuse (7.5 amp fuse which came with the pump) to 87 terminal on relay.

30 - Power: Power side directly to pump.

Runs great! I went with the heavier wire so I wouldn't get a voltage drop from the smaller guage wire running all the way back to the pump.
Good luck,
MIKE

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Fuel Pump Problems	blue302	Windsor Power	3	07-08-2005 10:18 PM
Fuel pump will not stop running	MustangGT1990	Windsor Power	7	01-29-2003 10:41 PM
Rebuild Questions?	5.0L_Of_Fury	Windsor Power	5	12-29-2002 11:39 AM
Possible Fuel pump failure	FiveORookie	Windsor Power	1	12-23-2002 01:28 PM
EFI to carb, fuel pump wiring question	Radon	Windsor Power	4	05-02-2002 06:47 AM

10-07-2004, 05:46 PM	#7
79Stang351W Registered Member Join Date: Apr 2000 Location: Sunbury, PA Posts: 6	On my carbed 79 Coupe with 351W, I ran a Mallory Comp 140 with 1/2 in. lines and a 1/2 in. return. I used a Radio Shack 30 amp relay. I also picked up a socket that fits onto the relay with wires for splicing into. I mounted the relay inside the trunk on the spare tire well. I drilled a hole in the sparetire well to put the wires through and put a rubber grommet in the hole to protect the wires. I used 10 gauge wire for power supply and ground, and 12 guage for the switch. Anywho, on the specific relay I used, Radio shack 30 amp, connect as follows: 86 - power switch: 12 guage wire to your on/off switch (You can connect into your ingnition switch wires, but I just used a 30 amp double pull on/off switch and ran it to the battery connection on the solenoid. I wanted to be able to shut off the pump and let the engine run to drain the bowls for jet changes.) Note: I also used an inline cylinder type 7.5 amp fuse for this switch. 85 - Ground. 10 guage wire to frame in rear. Two wires, ground wire from the relay and ground from the pump connected to the ten guage wire then to the frame. 87 - Power: 10 guage wire from positive side of battery with heavy duty cylinder type fuse (7.5 amp fuse which came with the pump) to 87 terminal on relay. 30 - Power: Power side directly to pump. Runs great! I went with the heavier wire so I wouldn't get a voltage drop from the smaller guage wire running all the way back to the pump. Good luck, MIKE