Fuel lines for EFI conversion '70T

[belling]

I'm rebuilding my '70T engine and am considering conversion from Webers to EFI using the PMO throttle bodies and Clewett Engineering TEC-GT.

What is the best approach for running a fuel return line? Can I put the new pump where the old one was and just run the return to the tank like MFI? Should the pump go in the engine compartment with a hard return through the tunnel? Has anyone done a similar conversion?

Thanks,
Jeff

[jpnovak]

Does your car already have a hard return line in the tunnel? Some of the 69T did not and a few early 70T did not. Somewhere along the line the factory transitioned to the 3 port Bosch fuel pump and return lines were standard on all 911 models.

The simplest path is this...

1. supply line from tunnel to pump mounted in stock location. You will have to build an adapter depending on which pump you have. Some of the pumps are similar in size and will fit the factory clamp. You will need a 180 deg bend coming off the pump outlet to bring the line back up the car underside.

2. pressure line from the pump runs under the DS longitudinal rail using the factory body clip. to the hard line in the longitudinal.

3. pressure line from the hard line in longitudinal to your filter assembly of choice.

4. Filter assembly to DS EFI fuel rail inlet.

5. Crossover from DS fuel rail to PS fuel rail

6. PS fuel rail to regulator
7. regulator to return line in the tunnel. Can go behind shock tower or through engine tin to get back to the tunnel.


If you are rebuilding the engine consider having MFI ports drilled. I have adapters available that will allow the use of EFI injectors with MFI stacks. These are available from our host.

[belling]

There's a hole in the tunnel bulkhead for the return line but no hard line installed.

[jpnovak]

Then you have to install a hard line or pull a later polyamide style hose through. Its relatively easy with the engine out.

[Bergo]

I found it pretty do-able with the engine in, just needed to unfasten my hand brake, shifter, and PSJ cover. be mindful to route the lines through the factory steel loops along the side so the lines don't interfere with your shift linkage or throttle

[BoxsterGT]

For an EFI system the fuel pressures are much higher (10x) and the correct fittings & hose/lines must be used.

I have both Metric Flare and Metric Compression Ring fittings to use your original steel hardline and can supply SS tube or Polyamide tube for the return in the tunnel.



Rear pumps can and do work well though the best place for the pump is up front, as fuel pumps are better pushers than suckers. Here are a couple of front pump fitments on early cars you might consider........





They both have later gas tanks but hoses are easy to make up for your early tank and specific needs.

I have made up a number of fuel systems for PMO conversions, and have my "direct-connect" AN-6 to Metric fittings for just such a need. All hoses are E-85 rated and fully pressure tested before shipping.

For information, please email me. NO PM's.

Len at Autosportengineering dot com