Wiring for Hobs an Double Pumper ??????'s

[RUQWKNF27]

OK I have a double pumper a relay an a hobbs switch. Now how in the world do I wire all this up. I know I will need some 10 g. wire for the 2nd pump thats a no brainer.. The guy I bought this from tried to explain all this to me but I am too stupid to get it !!!! Right now I have a 340 hot wired with a reactronix relay off the hot stud can I still keep this hot wire kit on the car for the main 1st pump on the hanger?? Just need to know where you got power from for the hobbs an where did you get power from for the realay??

 

[N2HIPSI]

My hobbs switch has two wires coming out of it. I ran one to the back of the alternator and the other to the second pump at the back of the car.

 

[RUQWKNF27]

Hum

This si what I have come up with an its probaly wrong!!! I have a relay with 4 terminals on bottom...
1) Run 12 V. from fuel grey connector by Dr side VC to one side of relay.
2) Then run power form hot stud in one side of relay an when the boosts comes up to whetever set psi it will energize the hobbs in turn closing the circuit in the relay an then sending power from the hot stud out to the other side of the realy to the 2nd pump.
3) Last connector on ground...


But do I need this relay ?? Its as if im using 2 hobbs one actual hobbs an then the relay itself.. Could I not just use the hobbs straight off the hot stud using a vacumn source?? There fore only needing one 12 v supply??

 

[RUQWKNF27]

####

I mena whats the use in the relay when the power is already gonna be activated by boost psi... If the boost makes up the power then why do you need a relay to make it up too?? Does that make sense??

 

[pacecarta]

the hobbs provides a turnon point based on boost, so lets say you set it to 10PSI , when the boost hits 10PSI the hobbs switch closes , then you run that feed to a relay to take the load of the pump off the hobbs switch because the relay is connected with a larger wire to the alternator .
this allows you to drive around town and not have both pumps on and also makes it easier to keep the car from being excessively rich at the bottom.
my 86 was wired straight through the hobbs when i got it and i have since wired a relay after the hobbs . i also have a wire tapped off the output to a light in the dash (behind the power injection on the right side) so when the pump is activated i can clearly see it is on during a run

 

[VadersV6]

I used a hobbs switch and a KB boost a pump on my blown cobra. Its a nice piece, and Im surprised I dont see it used more often on turbo regals. It gets switched on by a pressure switch at a given psi, and then overdrives the voltage to the pump, from 12 to 18 volts, if you turn the knob on the BAP all the way up. But it somehow modulates the voltage so that the pump doesnt get overworked. If you increase the fuel pressure, volume of fuel drops. The BAP is set up to stop this problem. 03 cobras have a dual pump from the factory, and there is a way to wire it up for a dual pump application. You dont have to worry about relays or anything. You just splice the BAP into the pump power wire, ground the BAP, and you're good to go. Takes like half an hour to install. I was making 500hp at the wheels with a single 255 pump and a BAP set to only 10% overdrive. There was plenty of fuel left. You really dont need a dual pump with this kind of setup, cause you can get the volume you need by just upping the voltage. But its not overdriving the pump all the time. Only when you're above the set pressure of the pressure switch (hobbs).

 

[dentmasters01]

the hobbs provides a turnon point based on boost, so lets say you set it to 10PSI , when the boost hits 10PSI the hobbs switch closes , then you run that feed to a relay to take the load of the pump off the hobbs switch because the relay is connected with a larger wire to the alternator .
this allows you to drive around town and not have both pumps on and also makes it easier to keep the car from being excessively rich at the bottom.
my 86 was wired straight through the hobbs when i got it and i have since wired a relay after the hobbs . i also have a wire tapped off the output to a light in the dash (behind the power injection on the right side) so when the pump is activated i can clearly see it is on during a run

BECAREFUL ! all you know by the light is that the hobbs switch is working properly. That doesn't mean your pump is running. If the wire came loose from your pump, your light would still come on.

 

[pacecarta]

the light is tapped off the feed to the pump and while i suppose its possible for the wire to to come off the pump it does let me know when the pump is supposed to kick on and that the hobbs is functional and the relay is indeed passing the current to the pump.
i would suppose the capers led knock in the dash would let me know soon enough if the pump wasnt working.

 

[dentmasters01]

the light is tapped off the feed to the pump and while i suppose its possible for the wire to to come off the pump it does let me know when the pump is supposed to kick on and that the hobbs is functional and the relay is indeed passing the current to the pump.
i would suppose the capers led knock in the dash would let me know soon enough if the pump wasnt working.

By the time the knock indicator lets you know it could be too late. Especially at a high boost level. I talked to red armstrong about his double pumper (which I have on my car) and he used to include a light just like your talking about, but a couple of customers pumps failed and never knew it because the light was on.

 

[pacecarta]

yep your right , dont know what im thinking , the second pump for that matter doesnt get near as much use as the primary so for for that matter the primary pump could go and that pump has to rely on the ecm connection the factory relay and a hotwire relay ,
, even if i went to a stand alone like an aeromotive that could fail or the wiring could have issues and same thing

so your point is what???? guess i should just park it and look at it then HUH

 

[dentmasters01]

No, don't park it. Just sell it to me! :biggrin: I was just saying you shouldn't rely on the light to tell you everything is ok. All that tells ya is that the bulb isn't burnt out. It's probably good to pressure test the hobbs everyonce n a while to hear the 2nd pump come on and its working ok.