Sumping a stock fuel tank
Have you ever had a fuel starvation problem during hard launches? The OBS trucks are notorious for this issue. Here is the solution, a rear mounted fuel tank sump. Below is a list of all parts used. SummitRacing.com was sourced for all parts.
I use 1" x 1/8" flat bar to make the mount for the pump and filter. To isolate pump noise I wrapped the clamped pump and filter with an old 10-speed tire tube.
This list includes all items for a return style fuel rail.
1/2 NPT dual outlet sump CEE-4041
Hose purchased for RCSB
-6AN = 3/8" inside diameter (20 feet) SUM-230620
-8AN = 1/2" inside diameter (6 feet) SUM-230806
1/2" INSULATED CLAMP 10PACK SUM-G1882
outlet side:
1/2 NPT male to -8AN male outlet fitting SUM-220847
-8AN female x 90 degree hose fitting SUM-220887
-8AN hose
-8AN female to -8AN hose straight fitting SUM-220890
-8AN male to 18mm x 1.5mm male fitting AER-FBM2244
Bosch 044 pump held to the frame by 2.5" Tbolt hose clamp (2) SME-240250 (clamp)
Weber carb 12mm x 1.5mm male x -6AN male adapater EAR-991944ERL
-6AN female to -8AN female straight swivel EAR-915186ERL
-8AN Summit fuel filter held to the frame by 1.5" Tbolt hose clamp SME-240175
-8AN female to -6AN male reducer EAR-9892086ERL
-6AN female to -6AN hose fitting SUM-220690
-6AN hose
-6AN female to -6AN hose fitting SUM-220690
-6AN female to -6AN male gauge adapter swivel fitting (optional) R-100199ERL
-6AN male to 3/8 ID Russell fuel line adapter 640850
return side:
1/2 NPT male to -6AN male outlet fitting EAR-981668ERL
-6AN female x 90 degree hose fitting SUM-220687
-6AN hose
-6AN female to -6AN hose fitting SUM-220690
-6AN male to 5/16 ID Russell fuel line adapter 640860
The sump will need to be welded to the rear floor of the fuel tank. This will require removal of the fuel tank and plastic liner on the OBS trucks. Do not attempt to weld this in yourself, take the empty fuel tank and sump to a radiator shop that can cut and weld it with a shielding gas filling the tank to prevent the risk of explosion from the gasoline vapors.
Remove the factory fuel pump from the OBS pump assembly and close off the fuel pump supply and return tubing by welding or flatten it and bend it over on itself. You can also remove the supply and return fittings on the top of the fuel pump assembly. Take some JB Weld and fill in the holes. Cut and remove the wires that went to the old pump. All that should be left is the vapor vent tube going to the filler neck and possibly the fuel vapor line if you decided to keep it, I close it off.
When you assemble the tank you will need to cut an area from the plastic liner to clear the sump. The parts above are listed in order of assembly going from the fuel tank towards the fuel rail. If you're worried about keeping the aluminum fittings pretty, be sure you buy AN fitting wrenches.
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Originally Posted by knute_gis
