M104-AMG

iTrader: (8)

After reading all the fuel-pump re-wiring threads, I finally decided to make this a priority as the FD "died" at the start line of the local AutoX.

The root cause was too much resistance in the circuit (going through the ignition switch, etc.) esp. with a Supra pump, thus causing the 35-amp circuit-breaker to thermally trip, and then reset in about 2-minutes, even with the Dale Clark fuse-box re-wire.

My criteria for a successful re-wire is NEW 10-gauge for BOTH the positive & negative; a CONTINUOUS duty relay; use the existing circuit to activate the relay; and route the wire in safe manner

West Marine duplex 10-gauge fine-stranded wire in a sheath. Perfect for the run from the battery, but not safe for submersion into gasoline esp. with 10% ethanol. It is, however, gas resistant, just not submersible.

70-amp CONTINUOUS duty Bosch Relay from Texas Industrial: relays continuous duty 12 volt & 24 volt DC power relays,starter relays

Lowes had in stock, oil & gas resistant and submersible 10-gauge wire. This wire has a NYLON insulator, not vinyl or PVC.

West Marine also had NYLON ring crimps that are fuel-submersible safe.

For routing, I was able to use the existing LARGE hole in the fender near the master cylinder.

To get into the cabin, if you pull-back the driver's side fender liner, you'll see a LARGE rubber cap that passes into the cabin just behind and left of the interior fuse-box.

By pulling up carpet, you'll see the plastic channel for existing wiring. Open the channel, and you'll have a safe place for the 10-gauge wire.

From there I used a fish-tape to route a pull-line through the rear plastic to the tank, being mindful of any sharp turns, pinching, and keeping it away from the hatch.

New wire into the tank passed through an ATL bulkhead connector, pn# ATL CFD-504 : http://www.jegs.com/i/ATL/046/CFD-504/10002/-1

Good luck!

:-) neil

M104-AMG

iTrader: (8)

Attached are two pics of the 10ga submersible wire from the following perspectives:

1) wired at the fuel-pump;
2) wires passing through an ATL Electrical Bulkhead connector

:-) neil

RENESISFD

iTrader: (13)

I am interested in your success of that bulkhead connector as many times the fuel will wick up through the wire.

This is a better option for you to use for not much more money. I guess you just need to check amperage to be sure this will work.
Racetronix - Universal Bulkhead Wiring System, 4-Way

Also you can get a much more compact and cheaper relay here RELAY 70 AMP 12V SPST HELLA 87432B - 75360

M104-AMG

iTrader: (8)

It's been a couple of weeks, and no wicking. IMHO, wicking occurs only if the wire's insulation is non fuel-safe submersible, as the metal wiring it's self doesn't wick.

I contemplated the Racetronix, but 14-ga. wire is NOT enough for my current application, nor enough head-room if I ever go duel-pump which will be mounted on the rear sub-frame above the diff, which will make the in-tank pump more of a "lift pump" and will reduce it's stress to also pressurize the system. 10-ga. wire handles a little more than double the current of 14-ga wire. Also, the Racetronix is double the price of the ATL.

I don't like "blade" interfaces for such large current. If you look at the BOSCH relay I chose, it uses RING connectors. Also, it has reverse polarity/back-feed protection for both series and parallel protection.

More info on backfeeding: http://ls1tech.com/forums/stereo-ele...g-problem.html

:-) neil

04G35S

iTrader: (10)

I used a stainless bolt and insulated washers to go through the cover. You have zero wicking then and its an all around cleaner setup.

M104-AMG

iTrader: (8)

Looks great! Where did you source fuel-safe insulated washers / grommets ?

I couldn't determine from my local Ace Hardware if their insulators were fuel-safe, let alone their material composition. I was looking for Nylon or Teflon, and they had none.

BTW: be sure to check your heat-shrink for decomposition due to fuel reaction.

:-) neil

04G35S

iTrader: (10)

I ended up using Nylon washers to seal the washers. You cant really tell in the photo. I too looked into if the ones you can buy at True Value Hardware were fuel safe. That being said I have one soaking in some E85 for the last month... I'll check how it looks tonight!

Samito Built

iTrader: (38)

You right as soon as the heat shrink touches fuel it slides all off within time. Tape also has a bad reaction to fuel. I'm going to post my fuel pump setup dual Walbro 416 with 8 gauge wire.

04G35S

iTrader: (10)

Ill have to pull out the assembly and take a look, it has been submerged now for about a month. I was thinking of changing to twin Walbro 460lph pumps anyway.

Is there a fuel safe heat shrink out there?

Samito Built

iTrader: (38)

Ive never heard of heat shrink that can take the abuse of fuel. But here's my setup its -8 feed -8 return and dual walbro 416. The return is 1/2 line and I have it feeding in the middle of the FP socks. The wiring is 8 gauge and the pumps are triggered by stock wiring via 40 amp relay to battery with 40 amp fuse. This is the 3rd time I upgraded but shouldn't have to touch anything unless I want more then 580whp.

ZE Power MX6

iTrader: (157)

You can get fuel safe heat shrink from McMaster Carr.

Samito Built

iTrader: (38)

Nice!

04G35S

iTrader: (10)

Samito,
That is a nice setup! Where did you get the wire terminals? I may need to do the same this winter!

04G35S

iTrader: (10)

Also wouldnt 10ga wire be enough for those two pumps?

My current wiring is all 10ga with a 30A fuse and relay. I would hate to have to change it all out again!

Samito Built

iTrader: (38)

ATL Fuel Cells CFD-504 - ATL Electrical Bulkhead Fittings
ATL Electrical Bulkhead Fittings CFD-504 - Free Shipping on Orders Over $99 at Summit Racing

You have to make the white rubber bore a little bigger to fit the 8-10 gauge. But that was easy just use a solder gun to make the hole bigger. The seal on this is perfect 100% leak free and safe.

I went with 8 gauge for added safety on the wiring each pump draws 12.9 v to 13.2 in idle. So under boost between both pumps could be calling it close on 10 gauge and (1) 30 amp relay. I would say for a single walbro 416 it would be perfect. But I would still recommend the 8 gauge if your running duals IMO. But at times I do like to overkill on race stuff.

04G35S

iTrader: (10)

That is understandable. Maybe I'll upgrade to 8ga and 40a fuse and relay when I add an additional pump. When I bought the car it had dual 255's and the guy ran a 12ga wire... it was completely melted.

On a side note I wish I could buy just the bracket that the pumps mount to since mine has so many holes now.

Samito Built

iTrader: (38)

CJ motorsports is pretty nice BUT it doesn't come in -8 and its also pretty expensive. You cant run big gauge wire pass through there bulkhead. especially if you run the big stuff through the fuel sending unit. That's why I just built my own cheaper and efficient.

TwinCharged RX7

iTrader: (14)

I have dash 8 on my CJ holder. All you have to do is call them and they make it any way you want. I have a full parallel feed system, two -6 feeds (one for each pump), single -8 return

Samito Built

iTrader: (38)

The website is a little misleading didn't know you could upgrade the lines. But hey good info

phunk

The CJ hanger has 6 wire positions, so each pump gets 2 wires of its own. Therefore you would never need to run the 8 gauge wire like you mention you did. The high output in-tank pumps average around 15amp and can momentarily spike 20amps during high pressure from full boost. None of these pumps require dedicated 8 gauge wiring.

As for a -8 return, you can simply drill the hole larger and put a -8 in it. That said, if you need a -8 return, I would solve the issue at its root: stage the secondary fuel pump... no engine needs 800lph of fuel at idle and cruise. Use your engine management system to ground the secondary pump relay based on boost pressure and/or RPM. If you have an older EMS that doesnt include configurable outputs, Honeywell sells what is called a Hobbs Pressure Switch (around $40) that can serve this function.

04G35S

iTrader: (10)

So if I add another Walbro 460lph pump should I switch to 8ga or is 10 and a 40a fuse/relay enough?

The prior setup was two 255lph pumps on 12ga wire. The prior owner said the car put down 505rwhp. I changed to a single 460lph pump and 10ga wire. I am starting to think that wont be enough to maintain the 500+.

Speed of light

iTrader: (8)

10 gauge is more than adequate (90 deg C or higher temp rating is a plus). Be sure all of the connections are good & solid. I agree with poster who suggested avoiding 'blade' connectors at high current. A good quality relay is also essential.

RENESISFD

iTrader: (13)

OEM'S use spade connectors on high current circuits all of the time. There is nothing wrong with the design.

phunk

That pump only draws enough current to need a 12-14 gauge. But if you plan to run both pumps on the same wires (not advised) you will want 8 gauge wires.

Each pump should have its own 20 amp relay and its own 12-14 gauge wiring.

phunk

Agreed, so long as the spade are tight and in good condition. I have only seen issues with spades when they are loose and limited in contact. I will often tighten up the spade a little with pliers before putting on. If I have doubts about it having adequate contact, i will soldier over it all to basically fill in the gaps.

These in-tank pumps are all 15-20amp tops... these are not heavy current devices. While the factory fuel pump wiring is a little skimpy and should be bypassed, we do not need to take the same measures as if we were running 440v 3-phase 100amp service into the gas tank.