Plumbing the EFI fuel return for twin tanks - need ideas

The marine fuel valve from Pollak, listed as a "Standard Ignition" part number, is an "FV6 Fuel Valve". You should be able to order this from a NAPA store (if you're a Yank).

Gary, It's a three port. As used in a boat it would have two tank feeds into a shutoff valve at the carb. I'm using it to divert return fuel from the overflow in the fuel surge tank. Left fuel pump on means we return to the left tank. Right fuel pump, right tank. I wanted to avoid putting 16 gallons into an 8 gallon tank.

I have two low pressure fuel pumps feeding a surge tank through filters and one-way valves. A high pressure pump picks-up at the bottom of the surge tank, circulates fuel through another filter and around the fuel rails and to a fuel pressure regulator which dumps back into the surge tank. Overflow from the surge tank goes back to the tank which is supplying the system.

Once I have the prototype debugged I suppose the shop where I get things made can build more tanks if anyone needs one for an ERA.

 

[Gary Gibbs]

Re: Plumbing the EFI fuel return for twin tanks -

Ok Mark I am ready to buy the marine version, and hate to be a pain in the butt, but ... Specifically where did you buy yours and what was the part number at that vendor? I went to Pollaks website but the fuel selector valve portion is down now, etc. Thanks for the help.

 

Re: Plumbing the EFI fuel return for twin tanks -

Gary,

I got the valve at a speed shop in Berryville, Va. but it came in a "Standard Ignition" box so I'd have to believe you can order it from NAPA anywhere.

Mark

 

[dave harris]

Re: Plumbing the EFI fuel return for twin tanks -

Gary,

Pollak makes a great valve for use in twin tank operations. It is a 6 port valve and instead of being a solenoid (i.e. need to keep it energized when on the "aux" tank) it is motor driven with automatic shutoff switches so the motor dirves it to whatever position you want it in (tank 1 oe tank 2) and then it shuts itself off. Additionally it automatically switches the tank sending units so you can run a single gauge and only run 1 wire up to the dash.

The 6 ports allow you to use one side to "feed" fuel and one side to "return" fuel. Look them up on the web and they show plumbing diagrams and everything - order from Napa stores - I think mine cost about $80.00 including mating plug for electrics, switch and valve.

 

[dave harris]

Re: Plumbing the EFI fuel return for twin tanks -

Ok, so that's what I get for not reading the whole post /ubbthreads/images/graemlins/smirk.gif- information has already been given above - sorry for the bandwidth waste.
/ubbthreads/images/graemlins/crazy.gif

 

[Jeff Leaver]

I have a mid engine gt-40 type car and went thru quite abit of trial and error. I have twin fuel cells with a balance tube at the bottom, it is about 1" tube. I had two fuel pumps and two fuel filter off of the cells, and two lines going to my pressure regulator and one line out to my carb. What I did was plumb in a oneway valve before the regulator on each side to stop the fuel from going passed the regulator and back to the other side. I did this because I was road racing the car and did not what to run out of fuel in a hard corner from fuel being forces thru the balance tube to the other tank. I would also run both fuel pumps at once. My biggest problem was under hard acceleration or in a long turn fuel was being forced up the vent tube and out the back of the car.I received a few blak flags for this one ! The solution I came up with , was, to connect both vent tubes togather as high as possible and install a T fitting and run another line to my filler neck. Then I vented my filler neck above the return line and ran it out the back. Not sure this was the best solution but it worked for me. Good luck.

 

[Dimi Terleckyj]

I have read with interest all the replies.
Most of the proposed solutions create too many bits and pieces that can and will go wrong.

I have in DRB#68 twin tanks with a cross feed tube of 5/16 diameter to link the 2 tanks and allow them to equal out without allowing surge from one side to the other located at the bottom of the tanks.

My filler necks are joined just below the filler opening to one another with 44 mm filler pipe which allows filling of the 2 tanks from either side but doesn't allow crossover surge as the filler cross pipe is too high above the tanks.

I then use one low pressure pump to fill my surge tank and a high pressure pump to feed the injectors and the return goes back to the surge pot and the overflow back to the tank it is drawing from.

I dont need to switch tanks, use only one fuel sender, one fuel gauge and the level is always even between tanks except for extended cornering either left or right but the amount that can transfer is minimal due to the small crossover pipe.

I have built into the tanks a small sump below the tanks which the crossover pipe connects and small dams inside the tanks around the sumps which retain fuel on downhill runs.
This way minimal components, maintenance, and simplicity in use.
Photos of the tanks can be seen in my build thread.
Dimi

 

Wow, there are some mighty complicated plumbing systems out there !! Here is what has been successfully in use for the past 4 years on my car and delivers enough to fuel 525hp from an all aluminium 7.0ltr small block with Motec M48 and Jenvey IDA style throttle bodies. No switch over valves or valves of any kind and only one fuel gauge !!

When the ignition is switched on the low pressure pump primes the swirl pot / header tank. When the starter button is depressed, for safety reasons the ECU allows the crank sensor to kick in the pressure switch to power up the two injector pumps. By the way we used two pumps in tandem as a failure back up rather than for fuel volume delivery reasons.

Twin tanks connected by dash 14 balancer pipe.
Dash 6 pipes from each tank to T piece.
Dash 8 to large Fram steel canister fuel filter.
Dash 8 to Holley 'red' low pressure pump.
Dash 8 to Swirl pot.
Dash 4 bleed to r/h tank.
Dash 8 x2 to x2 Bosch motorsport injector pumps.
Dash 8 T piece to Fram steel canister fuel filter.
Fitting with Pressure switch for Motec ECU.
Dash 6 to fuel rails including bridge pipe.
Dash 6 from fuel rail to pressure regulator.
Dash 6 return to l/h tank.

Recommendation: Always use swage/crimp fittings on high pressure hoses and preferably on the complete system.

Hope this is of some help to all you plumbers out there!!

 

[Mike]

Thee are some good ideas put forward, but they all seem more complicated, with more bits to go wrong in time. My system is as basic as you can get, and seems to work just fine. I run a separate fuel line and return to each tank. The fuel line ends in a TWM fuel pressure regulator (one each side), and the return from the regulator goes back to it's individual tank. The output/fuel line from each regulator connects directly to a ONE WAY check valve, then to a 3 way 'fuel log' (mine is made by Aero-it's a 4 port log, and I plug one port) that sits right in front of the rails and just under the rear window frame. The output of the 'log' connects to the nearest fuel rail. My fuel pressure gauge connects to the front of the other fuel rail, which I can see from the driver's seat.
The left and right Holley fuel pumps obviously connect to the L and R fuel switches. (Anybody figure out why the L pump label is to the right of the R pump and vice versa?)
I've never had a problem with this, it looks neat and tidy, maintains a steady 43 PSI at red line, and puts out 370 RWHP on the dyno...just remember to switch tanks )

 

[Simon]

Wow, this is a six year old post!