MIGHTYMOUSE

iTrader: (59)

I get questioned on my set up very often and it has been around a long time. I had the opportunity to do a set up for a friend and thought I would put together a 2008 version of my 2003 twin in tanks (98 tank). My original system still on my car today can be found HERE

1. Run a fresh fused power wire front to back on the car for the second pump.

2. (Not shown) Select a relay location for the second pump. This car got one near the passenger kick panel; This location is roomy and close to whatever we choose to trigger the pump.
3. Get a nice clean ground for the second pump.

4. Cut the hole (hole was all ready cut for me in this case) and snag out the sending unit. You could also drop the tank. (98's are a PITA)

5. Assemble your Y block for the pumps. These parts are from a place that sounds like Foam D-poe and total about $10. I have never liked the 'brass T' versions. something like this clearly has more appropriate geometry.

6. Drill a hole and install a grommet; Run fresh power and ground wires through and once in place follow w/ some GOOP to seal.

7. Install pumps, these are GSS340 255lph high pressure same as what is in my car purchased from NEW ERA for $98 each
8. Solder and heatshrink connections to the pumps

9. Secure pumps to the bracket, use some hose between them to dampen vibration
10. Install the fuel injection rated 5/16 hose and secure with clamps. I prefer these type as the worm gear type can chew up the hose. I also put a dab of loctite on the threads for good measure.

11. Prepare to install, make sure area is clean. I reccomend unhooking the level sensor from the bracket, dropping the pumps in first, then dipping the float into the tank and reinstalling the sensor to the bracket. Don't drop the little lock!

12. When you have the pump socks over the ledge inside the tank everything should fall into place nicely. hook up the pumps and test em out! I cut the harness to remove from the car, use a good insulated connector to make the connections.


This was a @ $250 mod in total.
With a larger pressure line and fuel rails these same two pumps can fuel 1200hp, are quiet as stock, dependable as stock, and you can run the tank down as low on Empty as stock.
As installed here, I expect it to handle 800hp comfortably.
Full size photos available HERE

ls1fst98

iTrader: (3)

Very nice...I did the walbro 255 on my 98 and the location i was told to cut was way off on my car...but I have been seriously thinking about doing this as I am at the limits of the 255 already and havent even gotten heads or cam in the car.

Reject

iTrader: (24)

very nice MM

oh yeah quick question about how long dose the whole assembly measure? looks longer than stock?

MIGHTYMOUSE

iTrader: (59)

didnt measure it, its definitely all stock for 1998, the right pump as seen in the pics is in the exact spot as the original pump

Tiger2o69

iTrader: (16)

Help me out on the wiring if you dont mind. On pic 3 I see there are a lot of wires cut. What do those go to?

Right now i have a single pump. If I wanted to add another is all I have to do it run a relay for the second one and have it turn on with a hobbs switch.. And then leave the other one hooked up to stock wiring?

SuperZ

iTrader: (2)

Ok MM so you have 2 255s in your car with a 8an feed line, rails and regulator(boost referenced)?Do you still run alky injection? I figured you would need more for the crap load of power you have! That makes me second guess the expensive aftermarket tank inline pump thing...

Josh@KY-Turbo

iTrader: (120)

I am thinking the same thing now. I need to figure this out for my 99 Z28/SS Turbo Project.

(By the way your Turbo should be ready to ship shortly )

fenix999

iTrader: (17)

SO what happens to the fuel pump "bucket" that the stock fuel pump is enclosed in? I have a '99 with the plastic tank (so it might be different than yours) and i know my fuel pump was in a bucket when i swapped for the single walbro 255, does this twin pump setup require that you just "throw them in there" loose in the tank like that? I know its prob. a stupid question but hey it was buggin me and had to ask

MIGHTYMOUSE

iTrader: (59)

98s do not have the bucket, they do have little end caps that come off with the pump

i do spray a good amount of methanol, but that doesnt change how much these pumps are god for...just how much of their capacity I am using at the moment.

Josh@MASPORT

iTrader: (3)

and just to make this thread useful for every year f body here is what to do if you have a 99-02 car.

After step 8 add these quick steps in for your bucket:

Cut out the bottom and sides of the bucket:




Then place both pumps together and run -6an line from each pump to the stock barb fitting, in this case i used a T-fitting because a large Y block like MM used will not fit in the 99-02 bucket.



In the end the bucket should look close to this with the fuel pump filters not sticking all the way out of the bottom of the bucket, if they do the feeds will be directly against the floor of the tank and pick up debris and hinder flow:

SScam68

iTrader: (20)

how many amps does each pump draw?

NA$TY-TA

iTrader: (21)

Looks good Dave. Thanks for taking the time for the write up.


Kyle

Tiger2o69

iTrader: (16)

any info on the wiring

Josh@MASPORT

iTrader: (3)

i run a 16gauge wire from a hobbs (pressure) switch in the engine bay to a relay near the tank. then i have a 10guage wire from the battery in my trunk to the relay to an inline fuse then to the pump.

Tiger2o69

iTrader: (16)

thanks.. Thats what I was thinking. The other pump should run off stock wiring correct. And on the 99+ cars you need to keep at least a 1/4 or is it 1/2 tank?

Frost

iTrader: (45)

No stock wiring for aftermarket pumps; the voltage drop causes an over current consumption back at the pump in it's windings. For my 01, I know if I get it beneath 4 gallons and get into boost my FP will fall, indicating some uncovering.

Tiger2o69

iTrader: (16)

Well not actually stock... I have the racetronix hotwire kit for my 1st pump.. is that sufficent.

NSTY WS6

iTrader: (5)

So, is this saying that you need to run a hotwire kit to both of the pumps, and not just the 2nd one?

Also, if you run 1 pump on a hobbs switch/or switched by nitrous activation, do you need to install any kind of check valve in the supply line of the 2nd pump? Didn't know if the main pump would pump backward through the 2nd pump...

SScam68

iTrader: (20)

hence the question for how many amps each pump pulls

if you know the amp draw you can find out what gauge of wire to run.

Frost

iTrader: (45)

they are both aftermarket pumps and it is best to run new wire for their increased current demand. A voltage drop at the pump will cause high current ont he factory wire and could result in a pump running hot, burning up, or even failure at a connection point.

Some pumps HAVE to have a check valve to double up on; these do not. I know Aeromotive pump-based systems bleed down FAST; so I would imagine they may need one to double up and block the non-running pump