using OEM fuel pump relays ???

wayne petty · January 26, 2009, 08:42:00 PM

i have been thinking about putting the electric fuel pump on for a while.. but . i really don't like putting a switch on it.. or having it powered only by the key.. i was thinking of going to a buick 3 prong oil pressure switch.. as the outer contacts are connected.. the top one grounds when the oil pressure drops...

but i like to make life confusing.. i had a flash of brilliance.. why not use a volkswagen rabbit fuel pump relay... it turns on with the key.. triggered by the hot side of the coil for 2 seconds.. then it takes the minus side of the coils signal to keep it closed...

my thoughts about using it for the fuel pump are one thing... but... why not use the 10 amp max to switch on other circuits.. and control other relays.. like cooling fans.. daytime running lights... ect...

i am almost sure that the 31b connector goes to the negative side of the coil... (tach signal)

the newer cabriolets relays have larger terminals.. on 30 and 87..

so has anybody else done this?

Leon · January 26, 2009, 09:36:01 PM

I've always used an oil pressure switch, and on the Torino I also used that line to feed the electric choke so it wouldn't burn up if I left the ignition on for the radio by mistake.

The Paisano · January 26, 2009, 10:38:56 PM

Quote from: "wayne petty"i have been thinking about putting the electric fuel pump on for a while.. but . i really don't like putting a switch on it.. or having it powered only by the key.. i was thinking of going to a buick 3 prong oil pressure switch.. as the outer contacts are connected.. the top one grounds when the oil pressure drops...

but i like to make life confusing.. i had a flash of brilliance.. why not use a volkswagen rabbit fuel pump relay... it turns on with the key.. triggered by the hot side of the coil for 2 seconds.. then it takes the minus side of the coils signal to keep it closed...

my thoughts about using it for the fuel pump are one thing... but... why not use the 10 amp max to switch on other circuits.. and control other relays.. like cooling fans.. daytime running lights... ect...

i am almost sure that the 31b connector goes to the negative side of the coil... (tach signal)

the newer cabriolets relays have larger terminals.. on 30 and 87..

so has anybody else done this?

The Paisano · January 26, 2009, 10:54:04 PM

Quote from: "wayne petty"i have been thinking about putting the electric fuel pump on for a while.. but . i really don't like putting a switch on it.. or having it powered only by the key.. i was thinking of going to a buick 3 prong oil pressure switch.. as the outer contacts are connected.. the top one grounds when the oil pressure drops...

but i like to make life confusing.. i had a flash of brilliance.. why not use a volkswagen rabbit fuel pump relay... it turns on with the key.. triggered by the hot side of the coil for 2 seconds.. then it takes the minus side of the coils signal to keep it closed...

my thoughts about using it for the fuel pump are one thing... but... why not use the 10 amp max to switch on other circuits.. and control other relays.. like cooling fans.. daytime running lights... ect...

i am almost sure that the 31b connector goes to the negative side of the coil... (tach signal)

the newer cabriolets relays have larger terminals.. on 30 and 87..

so has anybody else done this?

chimp koose · January 26, 2009, 11:21:25 PM

Wayne am I seeing this right?Is this a fuel pump relay with a built in fuse for the pump side?All I want to do on my car is to feed power to a relay that will turn off with the ignition switch as per NHRA requirement . I also will put a switch in line with the power from ignition to the relay so I have the option of shutting off the pump with the engine running. I like the idea of putting a fuse in the high current side of the relay.Once again I thank you for posting such helpful information.

papastoyss · January 27, 2009, 12:53:50 PM

Quote from: "wayne petty"i have been thinking about putting the electric fuel pump on for a while.. but . i really don't like putting a switch on it.. or having it powered only by the key.. i was thinking of going to a buick 3 prong oil pressure switch.. as the outer contacts are connected.. the top one grounds when the oil pressure drops...

but i like to make life confusing.. i had a flash of brilliance.. why not use a volkswagen rabbit fuel pump relay... it turns on with the key.. triggered by the hot side of the coil for 2 seconds.. then it takes the minus side of the coils signal to keep it closed...

my thoughts about using it for the fuel pump are one thing... but... why not use the 10 amp max to switch on other circuits.. and control other relays.. like cooling fans.. daytime running lights... ect...The Rabbit relay with the fuse gave lots of trouble. It would overheat & melt connections. The 85 & up Golf & Jetta relay w/larger terminals is much more reliable.

i am almost sure that the 31b connector goes to the negative side of the coil... (tach signal)

the newer cabriolets relays have larger terminals.. on 30 and 87..

so has anybody else done this?

papastoyss · January 27, 2009, 12:58:02 PM

The Rabbit relay w/fuse gave lots of trouble. It would overheat & melt connections. The 85& up Golf /Jetta relay w/ 2 larger terminals is much more reliable.

38HAULR · January 28, 2009, 03:34:16 AM

We use a,similar device here,mandated for LPG powered vehicles,detects ignition activity and is used for controlling the gas lock offsTurn ign "on",and unless you actually crank or start,she shuts off around 5 secs. I used one,via relay to feed my electric fuel pump on a 46 Merc. One thing you do not want is .to be involved in a collision,engine stops,and you are pumping fuel all over the joint ,especially if you a unconcious or in a daze.........Frank.