Fuel Pump Direct Power Feed

[OMY31T]

hey guys, im doing this mod atm, and ive been wondering whether this would work or not.

im running a dual stage boost controller off a switch in my dash. im wondering if i run the battery 12v feed to my relay, and then run a positive feed from my dual stage switch to make the relay switch on and off, and then tap the battery 12v feed from the relay into the std pump positive feed would this cause any issues?

doing it that way, i can still run the reduced voltage when im just cruising around the streets on low boost, and if i want to give it a boot full and switch over to high boost(low boost is only 10 psi so the pump will suffice without the extra volts) it will pump the extra voltage from the direct feed into my fuel pump to get the max out of it. this in theory should work, but what im worried about is the extra voltage running back up the line on the stock wiring to the stock relay and causing a problem. it would have been good to beable to shut off the stock pump wiring altogether to switch between the 2 power feeds, but the issue there is when the lines switch there will be a momontary lapse in power to the pump.

is it worth a try or should i just run it at max all the time, your thoughts?

cheers.

Edited July 19, 2012 by OMY31T

[The Dan]

Why?

Why?

Why?

[OMY31T]

because i sit in alot of traffic, and i wanted to avoid heating up the fuel on hot days in summer....

[The Dan]

because i sit in alot of traffic, and i wanted to avoid heating up the fuel on hot days in summer....

You don't need to worry about fuel heating up in traffic. You can't rip massive skids when you're in traffic anyway. If the fuel temp is a problem, you can always fit an inline fuel cooler. Cheap and effective

[Kenna802]

Yeah i really dont think it would make that much of a difference between voltage drop and you running longer cables to your switch. There is a dropping resistor in the fuel pump circuit which kicks in only when the fuel pump primes. Just remember the less volts you run the more current you draw which in turn makes things more inefficient on the Electrical system.

[scotty nm35]

If the fuel temp is a problem, you can always fit an inline fuel cooler. Cheap and effective

What products would you recommend for that? I was planning to run a fuel cooler but wasn't sure how to go about it. The return line would have bugger all pressure so can you use a simple trans cooler?

[OMY31T]

scotty i have seen somthing posted elsewhere with regards to cooling on the return line. ill find it for you, somthing sydney kid posted from memory.

EDIT: have a look at this

http://www.skylinesa...ost__p__1664761

i found some on ebay

http://www.ebay.com.au/itm/Moroso-Fuel-Cooler-Aluminum-Heat-Sink-Polyethylene-Shell-Mounting-Hardware-/390441461633?pt=Motors_Car_Truck_Parts_Accessories&hash=item5ae81fe781

or these might be worth the money...

http://www.ebay.com....=item20c78de26f

and i also found these fuel coolers ROFL

http://www.ebay.com....=item4ab9e29bea

hahaha

i think ill just wire it straight in, its tried, tested and works. if i have fuel temp issues ill deal with it when it happens.

Edited July 19, 2012 by OMY31T

[scotty nm35]

The Sard one looks good but $350 for what is essentially a small trans cooler seems a bit steep.

[The Dan]

Yep, a trans cooler is all that is needed. Mount it in front or under the car. They are flat so they don't take up much room and work well

[abr33]

Hi guys, in my 33 gtst i have a walbro 400L pump, running fine on stock wiring at 338kw (so far) with 22 psi boost is it worth me doing the wire upgrade? like the full thing or just earth wire?

Its worrying me a little and will do it if it needs doing...

[Hanaldo]

Hi guys, in my 33 gtst i have a walbro 400L pump, running fine on stock wiring at 338kw (so far) with 22 psi boost is it worth me doing the wire upgrade? like the full thing or just earth wire?

Its worrying me a little and will do it if it needs doing...

Definitely do it mate, read the latest posts in the Hypergear thread to find out why...

[t_revz]

People soldering in at the terminals at both sides of tank lid with larger guage cable or are the terminals readily available to fully replace?

[OMY31T]

you shouldnt need bigger wiring in the tank... the only reason for the 8 guage from the battery is so that you dont lose voltage over a long run of wire.. as far as im aware, the stock wiring is easily capable of 13.8v from the relay to the pump.

cheers.

[abr33]

Thanks, ill get onto it

[abr33]

And can anyone tell me if normal wire and heat shrink will be fine in the tank?? Thanks

[t_revz]

Heatshrink and fuel don't get on well although there might be a fuel resistant type. Stagger solder joints regardless.

[Hanaldo]

you shouldnt need bigger wiring in the tank... the only reason for the 8 guage from the battery is so that you dont lose voltage over a long run of wire.. as far as im aware, the stock wiring is easily capable of 13.8v from the relay to the pump.

cheers.

Voltage isn't the problem, you can get 14v down any wire you like. The problem is current. You need a wire that is capable of carrying the correct number of amps (the exact number escapes me now, been too long since I did it) to the pump. Otherwise that wire becomes your fuse.

[DVS JEZ]

. Otherwise that wire becomes your fuse.

or a fire hazard

[OMY31T]

ok thanks for that info. i went and checked it out, came across this for anyone else interested

apparently according to the graph, the wire needs to carry min 15 amps to run at full capacity(outside effective range) but less than 25 amps. so in the effective range running 13.5v @ 255l/h its around 45-50psi and between 12.5 to 13 amps, so i guess going to supercheap and buying a roll of 25 amp wire for a whole $12 to run from the relay to the pump is definatly worth doing and should be even slightly overkill.

Edited July 21, 2012 by OMY31T

[abr33]

Did this mod, takes a long long time to do it right. I ran 50 amp wiring and a 70 amp relay (incase i go e85 twin pumps) to my 400L walbro, all works. (it doesnt work if its hooked up backwards and the pump sounds funny.) but hooked up correct polarity and presto.

Question, which fuse? im running a 25A atm, is this right??

And will I need a fuel cooler?