Fuel Pump Replacement

I recently acquired a 1973 911T with Mechanical Injection. I was trying to replace my fuel pump when I ran into a problem. The one that is currently on the car is located on the drivers side just in front of the rear wheel, and only has two fuel lines connected to it. I know from the owners manual there should be three lines. Is it possible for this to be original? If not, where was it located, and should I bother changing it?
Thanks for any help you can give,

Stephanie


[This message has been edited by sesob (edited 05-16-2001).]

[This message has been edited by sesob (edited 05-16-2001).]

Stephanie,

No,that couldn't be an original pump for an MFI system! And, that is the correct location for your MFI pump.

The question is, why did you think the pump needed replacing in the first place? There was quite a discussion about a similar matter last month.

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Warren Hall
1973 911S Targa

Hello

Seems like you have a newer Pump. They have the inlet and outlet on the oppesite end.

Only the 930 still had that pump and it has a black housing.

However if the pump has 1 bar and delivers minimal 2L / minute it should work.

The Turbo CIS Booster Pump will have up to 6 bar and run alone min 1-1,5 L/ minute.

The CIS frontpump is silver and has a blue ribbon or is complete blue and has 6 bar and 1 L/ min flow.

If it is a green DME Pump it will have 3 bar and run 1L/min. The larger one ( 928 ) 2L/min

All Bosch Pumps have Order numbers on the case. Some Porsche units carry Porsche order numbers.

MFI likes to see flow rate and some overpressure isn´t a problem for the pump. But the filter can collaps and the dirt will kill the Pump. Also it can burst the cold start injection and then your engine can be flooded while starting.

Wet sparks, missfire or even worser things are the results.

Grüsse

Stephanie,

I tend to think the MFI systems should have the OEM pump and nothing else ... that is what I stated in the following thread:
http://www.pelicanparts.com/ultimate/Forum3/HTML/008431.html

Is there any popping, missing, backfiring, or roughness anywhere in the higher rpm ranges on your car? If so, I would strongly recommend installing a correct fuel pump, as the existing one may not be keeping up with engine demands! The correct 'T' fuel line may be missing on your car ... hopefully not. It is the line that goes to the return line to the tank, and is connected to the return line from fuel filter housing, and also the return port from the pump ... the 3rd line your current pump is 'missing'!

The 'factory' configuration is illustrated in the followwing diagram of pump, lines, and filter housing ... #14 is the 'T-line' I mentioned:

http://www.pelicanparts.com/techarticles/911_MFI/filter_MFI.jpg
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Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 05-17-2001).]

I have read a few posts from you and it seeems that you are trying to diagnose a prob. with your fuel delivery. Is this true? If so, tell us what is happening to your car. Is it running? Running bad? Running lean? etc. Don't just go replacing everything. As you know, these cars can nickle and dime you to death. There are allot of people on this board who know these cars like the back of there hand and would be more than happy to help out. This board has helped me out tremendously with my 72 911 mfi. I learned the hard way with my fuel system. Bought new filter, than pump, than screen on tank, than had the tank boiled etc. Just to find out latter that the reason my car was starving for gas was because the additives they are putting into ca. gas had ruined the gas line that runs from the pump to the tank. Shows how much I know...
Happy posting

Since we are on the fuel pump topic, does it hurt or help to run 2 pumps, one by the tank the other by the carbs.(webers)

Tom,

If you were going to run two pumps, I think one per carburetor would be the way to go. There might be a corrosion problem with the hard line through the tunnel, but normally there is plenty of gas just by gravity pressure at the inlet to the pump in the factory location! Changing the supply hose to the pump is NOT recommended with a full tank of gas!



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Warren Hall
1973 911S Targa

Been there done that warren, it sucked too.hehe