Fule pump to the front??

[Phoenix]

With the new PMOs on my 2.4 T (with L cams), my mechanic is suggesting that I move the fuel pump to the front of the car to avoid potential Vapor Lock. Does anyone have any experience in this? Is VL a big problem? IIf it is, will moving the pump solve it?

Also, would a whole new line need to be installed or could the exisiting front to back lines adding in enough to allow for the pump suffice?

(As a reference the car will be rarely tracked and is predominantly a daily driver (now) and weekender (once I get a 2nd car)).

I'd appreciate the opinions of this very knowledgable board ;-)

[davis911s]

Phoenix I don't know who your mechanic is or how knowledgable about Porsches he is but the Fuel pump in my 77 IS IN the front of the car.

According to Waynes book page 99 there were a FEW very early 911s and 356s that had a fuel pump in the engine compartment but he doesn't cover it since not many 911s used them.

I doubt yours is there but I could be wrong.

As for vapour lock, yes I found that it is quite common with CIS but not sure about with PMOs. In CIS cars it is generally solved with a check valve. (or fuel accumulator, which yours doesn't have).

Good Luck

Shawn

[T Bird]

Phoenix
I converted to Webers many years ago and left the fuel pump in its stock location. I switched the MFI fuel pump with the Bosch roller cell fuel pump. It is a direct bolt-on relacement. The MFI wiring harness plugs right into the fuel pump. I have never experienced any vapor lock issues with the rear-mounted fuel pump.

If you really want to move the fuel pump forward, you would use the existing suction line in the tunnel. Since the pump would be located aft of the tank but forward of the tunnel, the existing suction line in the tunnel would become the delivery line. The return line in the tunnel would be capped on each end. Your biggest challenge would be finding a secure location for the pump (smuggler's box?) and re-routing the wiring harness and fuel lines.

Personally, I would leave the pump where it is unless you are experiencing a problem. Put your money in a Bosch roller cell fuel pump (2.8-4.2 lbs. of fuel pressure with return line fitting) and a good fuel filter set up (MFI filter works well but is pricey!!). Also, make sure that your fuel tank is rust-free. If you have any doubts, remove it and have it cleaned and sealed. These things will probably do a lot more to keep those PMOs happy than relocating the fuel pump. If vapor lock were to become an issue, then move the pump.

Good luck.

[katigbr]

Pheonix,
Not sure about the vapor lock problem. The fuel pump on the early 911s are located well below the engine and should already be out the "hot spots" . It is located in a bracket attached to the rear torsion/torque tube near the drivers side trailing arm attachment point.

I just moved my fuel pump to the front. I had a 2.4-27 MFI in my 72T and had to increase my fuel delivery for my conversion. Moving the fuel pump wasn't that big a deal. I removed the entire MFI fuel delivery assembly from the engine compartment, cut off the fuel pump mounting bracket welded to the rear torsion bar and plumbed new delivery and return hoses to the pipes coming out of the transmission tunnel.
The new fuel pump is located and mounted to the front suspension cross member. It connects inline between the outlet pipe on the gas tank and the transmission tunnel line near the steering rack.
The electrical connection is fairly straigthforward. A wire connected to the securely to the body with star washer and a wire to the fuse panel with power on during ignition and running.

I used a large hose clamp and rubber padding to attach the pump to the front crossmember.

Rick

[Oldporsche]

Probably the best argument for moving the fuel pump from the rear to the front is that it is much easier to push fuel than to pull it from the tank. The fuel pump doesn't have to work as hard. I have owned cars with them in both positions. The only reason I could find for moving the pump to the rear was for maintenance reasons.



Good luck,
David Duffield

[Phoenix]

Thanks for the input!!

Thanks to this board I can now speak somewhat intelligently to my mechanic (keep in mind it will still me talking ) I will asked him to hold off on moving the pump ) until I have a real problem. (I'm also getting low on P-funds)

The only current issue I have with it is it so damn loud! Everytime I start the car or sit at an intersection idling, the pump starts to "click" rapidly and loudly until it decides to stop (I can't correlate it to anything like engine speed)! It's getting a bit nervewracking especially given the wonderful state of the rest of the car. I'm going to explore putting a thick piece of rubber between the pump and the mounting point which hopefully will dampen things a bit.

[davis911s]

I WAS WRONG

So I guess the MFI equipped cars have a fuel pump in the engine compartment.

I can access this board from work, but only to read (can't post)

So I watched and wanted to apolagize for my incorrect input

Thanks again everyone. I guess I am still in the stage of
learning how to break things

Thanks again and sorry Phoenix if I started to lead you down the wrong path.

Shawn