fuel pumps for internal surge tank

  • Thread starter Thread starter CPLUCKER
  • Start date Start date
C

CPLUCKER

Guest
shopping for my new in tank surge tank set-up and I need some advice. I currently have a small pickup box with flapper doors, but I still starve for fuel when i get down to half a tank or so. So I am going to do a new set up with 2 in tank pumps, one in the left rear corner of the cell that feeds over to a box " surge tank" where the main in tank pump will pick up the fuel the the FI system. a couple of questions

1) I was planning on using a regular old walbro fuel injection pump for both of the pumps. is ther any concern using a pump that is typically designed for higher pressures in a low pressure/ higher flow capacity ? the "scavenge" pump will be almost unrestricted pumping from the cell to the surge tank

2) would you guys use a higher capacity pump for the scavenge ?

3) would you direct the return line from the rail to the surge tank or back to the main cell ? if you go back to the surge, you would get lots of recirc of the same fuel.

4) there is special high dollar fuel injection hose that is specified for in-tank use that is designed not to degrade when immersed in fuel, but it is crazy expensive($20 a foot ) know any good alternatives ?

thanks for the advice
Plucker
its 280z

4)
 
o.k. why ? the scavenge pump needs to flow at least as much as the main pump to keep the surge tank full . unless the FI return line goes back to the surge tank.

If you look at the 155 lph pump curve it flows 40 gph at 0 psi or 38 gph at 20 psi. since the the short hose over the the in-tank surge tank is going to have almost no restriction. it seems to me that this pump would act like a low pressure high volume pump.

The only in-tank pump i can find that is stated as a low pressure high volume is from fuel safe and is stupid money $250 or so. usa made walbros are $70
 

Attachments

  • pump map.jpg
    pump map.jpg
    64.4 KB · Views: 6
I've just started using my high volume high pressure (40psi) Honda OE pump as a low pressure pump to feed a.....large filter....and then an external high volume high pressure pump.

I've only had let's say 7 20minute sessions on it, but so far everything is ok.
 
No problem using the Walbro high pressure pumps in 0 pressure applications. They are a rotary vane setup unlike older high pressure setups. We always have the hose feeding the surge tank go through fuel cell foam to drop any air out. Same for the return line.

And keep using Walbro, my employees love ya. :023:
 
4 door surge tank, Holley (red?) lift pump into a fuel accumulator/filter and then to the high pressure pump. It will run the cell bone dry. On edit, the surge tank inside the cell is probably fine. What you need to do is have a lift pump to take fuel to an accumulator/filter. The accumulator/filter is pipes as follows:

4 fittings on the a/f: bottom, to main high pressure pump. Top: return from motor, line from lift pump, and return to cell surge tank. Mine is plumbed that way... sputtered coming out of 5 at RA and I coasted across the finish line with the motor off and in neutral, completely out of gas.
 
Last edited:
First of all, plumb your return from the engine fuel distributor to dump into the surge tank.
When you need the surge tank, the flaps are working for you to trap fuel (therefore not a lot of extra help is needed). In a cornering situation with less than a half full cell, the fuel inside the fuel cell will be on one side or the other for the length of the corner (measured in a few seconds). If your surge tank pump pickup is in the wrong side, it will cavitate, otherwise pump into the surge tank. The surge tank volume is around a gallon and will probably hold half of that in the same corner (unless you put a top on it -hint hint). In the few seconds that you are sucking fuel from the surge tank in the corner, how much fuel will your engine burn with the excess being pumped back to the tank? A gallon? No. No need for much extra being pumped into the tank from the aux pump.

Best feed for the surge tank is two low pressure pumps picking up from each rear corner of the tank. No cavitation. If you only run one aux pump, think about the track and put the aux pickup on the predominate outside side of the fuel cell.

This set up works very will to empty your fuel cell. The down side is that you may not have two miles of fuel left when the engine coughs as you pass pit in. :rolleyes:
 
Something that no one here mentioned was using good quality wire such as Tefzel in the tank. TXL, GXL, and the like will have the insulation swell and fall off with some fuels. Use good quality (expensive) stuff and you shouldn't have any issues.
 
You must log in or register to reply here.
Back
Top