fuel tanks; SWB & LWB the same ?

[typ901]

can I install a fuel tank from a SWB (carburetor) car into one w/ MFI ? I seem to recall something about an extra port in the MFI tank ?
any help appreciated.
thanks
jerry

[NeunElf]

In 1969, the first year of MFI, the part number for the standard 62 liter tank changed from 901.201.010.21 to 901.201.010.22.

I'm not an expert on Porsche MFI or the associated tanks, but many fuel injection systems do run a return line back to the fuel tank.

[michaelaiellosr]

If this schematic is correct it appears that only two ports are needed for the system. maybe one of the experts has more definitive info about the third port shown.

[edmayo]

I believe the the vent fitting is smaller on the SWB tank. The SWB tank will have two fittings, one was for the Webasto. The LWB tank has three; discharge, return, and Webasto.

[jesseandersson]

+ 1 on Ed's comment

[Jim Breazeale]

I believe the the vent fitting is smaller on the SWB tank. The SWB tank will have two fittings, one was for the Webasto. The LWB tank has three; discharge, return, and Webasto.

Ed is spot on, as usual.

Regards

Jim

[Bert]

Helpful information.

Will a carburated 911T have a return line in the tunnel or does one have to install one if your changing to an MFI engine?

[edmayo]

Depends on the year of the T. If 69-70 with front mount pump the return just went from the pump back to the tank. If 71 and later with rear mount pump then there was a return line in the tunnel. The return circuit however was only from the pump back to the tank

[michaelaiellosr]

That is a good question.

I' m not sure whether my 72 was carbureted originally or not, but it has both supply and return hard lines in the tunnel. The fuel pump mounting support piece (welded to the torsion bar tube) is missing, and I don't believe it is available. So confusion reigns. I had thought that the right approach would be to relocate the fuel pump to the front a la SC and later models, but maybe a better approach is to fashion a support piece and mount it by welding or bolt to the underside in the area where the factory intended it to go. Ed said he could provide a photo of the correct mounting in place.

[edmayo]

Here's your pictures of the pump mount. The part number is 911-501-023-01. You should try to get one through your dealer, it's often amazing what is still in the parts supply. Since this is welded to the torsion bar housing someone had to seriously want it off since that would have involved a lot of cutting.