MFI fuel delivery issue

[arringto]

Question for someone. . . I am in the middle of installing 72 2.4T MFI motor into my 68 911 Targa E. The owner was gracious enough the give me a fuel pump and fuel filter with the motor. I have noticed something, both of these units require a return line to the fuel tank. (looking in a Haynes manual). From looking in the bare engine compartment I do not see a second line. Any advice or thoughts on how to work around this issue would be greatly appreciated. .

Thanks,
Alan

Arringto

[Bobboloo]

You say your car is a 68' 911 Targa (E)? Is your car actually a 69' model manufactured in 68'? The reason I ask is because "E" stands for einspritzen which means injection as in fuel injection. 69' was the first year Porsche offered MFI on a production car. So if it's a 69'E then you should have a return line to the gas tank. It would be located next to the send line from the gas tank where it exits the center tunnel of the car underneath the point where the two rear control arms attach to the torsion tube.

If your car is a 68' however it would have been a 911T,911,911L or 911S. All of which had carbs and there would be no return line.

Installing a return line is no small job either. It involves welding in the tube that runs through the center tunnel and changing the gas tank to one that has a return input. It would be easier to just put on carbs.

[206aa]

how about the mfi pump though? it is belt driven from the cam shaft right? Do you just leave it spinning freely? Also, how about the injector holes going into the manifold? Howdo you plug them?

Due to a password problem ( I tired to reset it and it wouldn't take the password that was emailed to me ) I had to switch usernames. so this is arringto.

There actually was a 911e in 68 from what I have read but not everyone calls it an e. It is the 140 hp 2.0. The T put out 110hp, S
put out 160hp. .

I have purchased the 2.4 to replace the 2.0.

Thanks for the help!

--Alan

[CamB]

You need to run a return line. It doesn't need to duplicate the factory setup (but could follow the logic).

I didn't install it, but have looked at my own '69T (it had carbs from the factory) which now has fuel injection.

My fuel tank had two connections (one out, one in). My mechanic installed a later 911 fuel line down the centre tunnel. Biggest issue I had was joining the two...

[Bobboloo]

The injector holes actually go into the head. You can plug the hole with a bolt that is the same length or slightly shorter than the injector. Main thing is that you don't want it protruding into the intake port.

The wheel on the cam can be removed or left on. If you are removing the MFI then you might want to remove the wheel as well so you can keep it with the rest of the MFI stuff incase you sell it down the road.

[Rot 911]

Don't give up on that conversion yet! Yes you do need a return line, but it does not have to be a stock set up. You can always pull the gas tank and have another fuel line connection brazed on. And while pulling another gas line through the center tunnel is a major PIA it can be done.

[jstobo]

Alan, there is no I repeat no 68E. In 1968 in the US you got the 911 or 911L. No 911S. The 911S was only available in Europe. In fact the 68 also has a shorter wheelbase than the 69 and up. The first two HP numbers you quoted are for the 69T, 69E. The 160Hp was for the 67 and 68S. In 1969 the 911S had 170 DIn HP. Give us you VIN and someone can decode it and tell you what year you have. It is important because 68 rear suspension parts are different from the 69's. Also the MFI fuel pump put up 1 Bar(14.7PSIG)of pressure. A carburetor fuel pump usually puts out inches of water pressure. You cannot use a fuel pump designed for the carburetor on the MFI. Just be sure you have the MFI pump.

Hope this helps.

[Todd Simpson]

Jstobo is correct, there is no 68E. I have read some books that talk about the changes in '68, but they are referring to the '69 model years. Pretty significant year for changes, longer wheelbase, slight flare in the fenders, FI for the E and S.

[206aa]

Thanks for the help guys. I will post the VIN so we can figure out exactly what year/model it is. My plan right now is to try and run the fuel line through the center tube since the engine and trans are out of the car now. I am concerned that there is not a return port on the tank but won't know until I take it out. If so, how difficult is it to install a fuel port?

I just hate the idea of ditching a perfectly good running MFI, (especially since the dual webbers I have will need rebuilds).

I have the fuel pump and fuel filter for the MFI engine so that will not be an issue. The main issues seems to be the fuel line. Can anyone recommend a book that addresses running fuel lines. I am assuming the line would be a mixture of metal and rubber tubing?

Thanks,
Alan

[206aa]

here is the vin# 11880067

Thanks,
Alan

[Bobboloo]

Your car is a 68' 911. It came with a 130HP 2.0. It was one of two middle models. (911+911L)

The 911L had the same trim as the 911S except it had the same 130HP motor as your car. The 911T that year had a 110HP motor and the 911S had a 160HP motor.

[206aa]

ahhh, that is why some were referencing it as an E model. So is it safe to say it has E cams and E pistons? I think they only made the L that year due to the fact they couldn't import the S to the US. I guess the S motor couldn't meet emissions laws. . Then came the cleaner running MFI S, the following year. Makes sense. Thanks Bobby!

--Alan

[Early_S_Man]

Alan,

The following fuel line diagram may be helpful ...

Please note that the two upper arrows are routed to the fuel tank, and the two lower arrows [below clamps #17] go to the MFI injection pump driven by the cogged belt.

[206aa]

This is perfect. Much better than the Haynes manual basic diagram. Thanks Warren. Now if I can just get the fuel line ran and the return port into the tank, I should be in good shape.

--Alan

[CamB]

I am concerned that there is not a return port on the tank but won't know until I take it out.

If you look up at the back of the tank next to the front cross member, you can see where the fuel lines connect to it. Mine were side-by-side, and if the '68 has the same tank as my '69, it will work (there are two).

Don't forget to make sure all fuel lines are fit for purpose (ie can take high pressure).

[206aa]

yeah, that is the grey area considering they went to MFI in 69'. I will try and take a look tonight. I have the rear of the car jacked up from the engine/trans drop so it might be difficult to get the skid plate off. . With any luck it will be there, I suppose it wouldn't be the end of the world if I had to get a new tank. .

[206aa]

thanks for replies by the way, everyone has been really helpful.

[CamB]

Another thing. My fuel tank could have come from anywhere (it is definitely pre-74 though - designed for a full-size spare). My car is not a shining example of originality.

[206aa]

Thanks CamB. So I am trying to get an idea of what type of fuel line to run. . would something like this work or do I need to use aluminum tubing as well?

[206aa]

That is braided steel line, the picture doesn't really show it that well.