electric fuel pump

[paintballtommy]

okay guys i got an electric fuel pump for my motor and i am haveing a ball thinking of how im going to wire this thing. instructions say to mount as clsoe to tank as possible and ground is well the the subframe im mounting it on. however the positive side is another story. how should i wire that. would it be okay to wire it into the positive side of the fuel tank sending unit so that way when i turn the key to run it will start pumping and only then? or will that not work and im retarded lol

thanks,
tommy

 

[gp001]

You should, at minimum, wire the positive side to a relay triggered by an ignition "run" hot source. I wired mine using a relay that is triggered by an oil pressure switch and has an inertia switch in the circuit. You do not want the pump to run with the engine off.

 

[HistoricMustang]

Yep, you need some type of "kill" switch in the system in case of accident and you are hurt bad and the pump keeps feeding a possible fire even after the engine has stopped.

HistoricMustang
www.historicmustang.com

 

[68_stanger]

as allready said I would use something along the line as this http://store.summitracing.com/partdetail.asp?part=SUM-G1438
for safety and then run it keyed with the ignition.

 

[gp001]

I would recommend using a GM oil pressure switch. There have been problems with the generic switches available at auto parts stores. I would also recommend a 3 wire over a 2 wire. You can get the GM switch at any GM parts counter using part# 3986857, or from auto parts stores carrying AC Delco using part# G1809 (tell them it's for a 74 Vega).

If you want more info on how to wire it up let me know.

 

[allcarfan]

did you think of picking up a regulator too?

 

[paintballtommy]

already got a regulator but thanks for that. so basically i need soemthing that wills top the pump if the engine is not running. even if the key is at run. okay i gotcha. so that oil preasure safetly switch is the way to go. thanks everyone. gp001 ill probably be pming you later today lol.

thanks again guys,
tommy

 

[allcarfan]

IM confused....

Why cant a toggle switch be used?

 

[gp001]

IM confused....

Why cant a toggle switch be used?

For a number of reasons. First of which is safety in a crash or mechanical failure. If you are unable to switch the toggle off in a crash, or are in the process of regaining control with a mechanical failure, it could be diastrous. Another reason is to prevent damage to your engine. If, for some reason, you were to leave the pump on you risk damaging the carb or worse, filling cylinders with raw fuel. As you know, in liquid does not compress as air/fuel mixture does and major damage would occur if you tried starting it in this "hydraulic" state.

 

[paintballtommy]

theres 2 types of switches do i need the 3 prong one or the 1 prong one?

thanks,
tommy

 

[gp001]

I always use the 3 prong. The 3 prong has a "start" bypass that will allow the pump to run when you start the car. The 1 or 2 prong versions wont turn on the pump until oil pressure builds. If you use the numbers I posted in one of my earlier posts you will get the 3 prong