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I'm in the middle of my building my father a 7 kit and its time to plumb the fuel system. I've searched and read until my eyes hurt, so can anyone help me with some advise on a fuel pump. I've fitted 2 4-gallon fuel cells and need to figure out which external fuel pump will work with the Honda S2000 F20C motor before I can go any further. I'm looking for what pump people have used with this particular motor in its stock configuration.

Thanks for taking the time to read this and I eagerly look forward to any insight you guys may have for me.

Dan

How do you intend to plumb the pump? Draw from both at the same time?

High pressure external pumps usually have a low pressure pump within the tank to keep the high pressure pump fed.

A large crossection crossover between and lower than the tanks to feed the high pressure pump should work well without internal pumps.

If using a typical return high pressure efi system, any gerotor for an injection system with at least 4 injectors should work fine. One pump is used on a variety of engine sizes, the difference being how much fuel is returned versus burned.

80s ford trucks have a high pressure pump mounted on the frame rail below the drivers foot well. Snag a used one for the bracket and cage. I believe I've posted photos of such a pump before. I'll look if you are interested in old Ford parts on your Honda hotrod.

Each of the cells have 2(-8AN)outlets, so I plan on going from one of each to a "T" and then to a Fram HPG-1 and then to the pump. On my last car, I used the other 2 outlets and simply made up a hose with -AN fitting and used it to equalize the level in the tanks so I didn't have to fill both tanks seperately. I wasn't sure on the stock S2000 fuel injection system if I needed to plumb a return line. If so, I can return to one of those outlets and plug the other since the plumbing to the "T" will also allow both cells to fill, just a bit more slowly.

The S2000 driveline in question is an early F20C out of an AP-1.

Thanks,

Dan

find out what the flow rating is on the stock pump and go from there. Ever consider feeding one tank with another? Maybe just utilize a common pump like a Walboro 255 in one tank and the other tank feeding to that? Otherwise any aftermarket external pump will work with a pressure regulator as long as it meets the minimum flow requirements (most external aftermarket pumps can feed V8's easily so you should have no problems... only the loud humm from the pump)

hi could be tricky having two tanks, its not a great idea to have a large hose at the bottom of the tanks to equalize the level. broken or cut hose will empty the tanks ,, fire maybe.
a low pressure pump in each tank with a switch to control, feeding one high pressure pump. would need check valves in the lines. return line could be a problem if you have one.

hi there are valves and switches made for dual tank pick up trucks ,. maybe lookup a ford system. places that sell add on biodiesel may have what you need.
i have one 12 gal tank in mine, think ten would do.
if you have to mount brackets in the tank, i found some great glue, sticks aluminum well, while covered in fuel. ask me i will look on the can.

Install the filter after the pump, a simple pickup screen before the pump will be sufficient.

IIRC the s2000 uses a returnless fuel system, so the rail has only an inlet, no outlet or pressure regulator.

1) You can add an outlet to the rail and install the regulator after the rail and route the excess fuel back to the tank.

2) You can install 'T' the line after the pump, one line to the rail, the other to a regulator, with the outlet of the regulator returning to the tank.

#1 is the traditional, return, system.

#2 is essentially stock, the regulator and pump are housed in the 'pickup assembly' in the tank. You can install the same arrangement externally.

As for transfer between the tanks there are several ways that the OEMs achieve this with 'saddle' tanks.

1) Gravity/siphon with a transfer tube between the sumps

2) Low pressure transfer pump

3) Returned fuel jet siphon

#1 is the simplest, and it does work. Concerns of fuel leaks are over-thought, any fuel leak is bad.

#2 more parts, more weight, risk of pump failure should the slave tank run dry

#3 is my favorite. Returned fuel routed to the slave tank, and is sprayed through a jet into a transfer tube. It creates a siphon effect, pulling fuel from the slave tank into the primary tank. It's very similar to a transfer tube but eliminates the chance of an air lock.


Here's a 'large-scale' jet siphon, these are commonly used in rural fire fighting to transfer water between portable tanks.



Water is pumped into the small inlet on the right, water is drawn from the tank through the square inlet on the bottom and out through the larger hose to another tank. They will really move some water, IIRC 600+gpm transferred for ~50gpm input. I used to be an NFPA driver/operator but it's been a few years.

Oh, just had this thought, you could use a jet siphon to transfer fuel from (one or both) tanks into a surge tank.

Well, finally had some time to work on my fathers project and decided to tackle the fuel system. Here's what I decided to do after taking a long look at it. One -8AN outlet from each cell plumbed together as a "balance tube". Then one outlet from the right side cell to a Fram HP-1 filter and then to a Walbro GSL394 pump and to the fuel rail via a 5/16"(8mm) hard line. The outlet on the left side cell that isn't attached to anything in the picture will be the return line. The stock return is 1/4"(6mm) and I will use hard line to get back from the regulator/fuel rail.

I spoke with a few guys at the shop and they all believe that this is a simple way to accomplish what I need. Any thoughts?

Thanks for looking.

I would suggest that you run the transfer hose from the inner nipple on the non fuel pump tank to the outer nipple of the fuel pump tank (fuel pump connected to inner nipple). This will hold more fuel in the pump tank during cornering.
Additionally I would put a free flow check valve in the transfer hose allowing fuel into the tank the pump is on. Vent the 2 tanks together and fill from the non pump tank(slowly!).

JMR

I prefer a 'rock catcher' before the pump with the filter after. Pumps are more efficient with the restriction after than before.

All you have to determine is that the return line doesn't return fuel faster into the LH tank than the gravity line can balance the two tanks. Otherwise, 1) you might starve the right side tank pickup and 2) you may overflow the left side tank. Worse case for #1 is at low fuel levels, gravity won't transfer fuel quickly. Worse case for #2 might be at idle right after fillup. BTW, fillup might take a longer time if you only fill one tank and let it flow thru the balance tube to the other.

I don't know the answers. Just offer it up as a "check-it-out" observation.

I have the same question as Chuck.

Any way you could seal the vent and pressurize the left tank with <5 psi of air to help transfer fuel?

If the left cell has outlets #1 & #2 and the right cell has #3 & #4, then how about this:

#1 and #4 connected at a "T" and feeding the pump while #2 and #3 also connected at a "T" for the return line? This way it should pull equally from both tanks under suction and should return fuel equally to both tanks as well from the regulator. This is an F20C out of an AP-1 S2000, so it does use a return like in its stock configuration.

Thanks for reading and adding your insight.

Pickup and return to one tank, gravity fed, filled and vented by the other. Raise gravity tank for better sump coverage for cornering when overall level is low.