Remove MFI pump only?

david482 · 06-12-2007, 01:05 PM

To shorten a very long story. I have done a huge amount of searching and have found a lot of great info in regards to the MFI system. The car, 1970 911E, sat for 12-15 years. I have cleaned & sealed the fuel tank, new screens and filters and all new fuel lines. The engine will run at idle and will move forward a bit but has no power when you really try to drive it. I think it is a fuel problem, I have replaced the plugs, wires, points, dist etc and the timing was set. I am thinking that the MFI pump may be a bit gummed up and was hopping to try and clean it and see if that is the problem. From my searching I know that I can check the rack while it's in the car and have not done that yet.

Now to the question.

Is there a way to remove the pump without removing the MFI stacks. I can sort of see 3 of the bolts holding it down but can't really find the 4th. I have looked at all the diagrams and instructions but have not seen any good instruction about removing the pump.

Scott Clarke · Scott Clarke's Garage

David-
There are four nuts that secure the pump to its mount- two on each side. You can get to them with a 1/4" drive extension and wobbly socket. Do you know about CMA?

david482 · 06-12-2007, 02:24 PM

CMA and I are good friends or at least getting that way.

304065 · 06-12-2007, 02:26 PM

I'll tell you how to get the pump loose, but it should be your LAST RESORT. "has no power when you try to drive it" sounds like a lean mixture to me, what is your air/fuel ratio? You really need to buy or borrow a wideband 02 sensor like the LM-1 in order to determine whether the problem is inadequate fuel or something else. Seriously, 90% of the problems with MFI have nothing to do with the MFI pump.

That said, you can't get the pump out without removing the lines and the stacks.

Be extremely careful working around gasoline, the injector lines are probably full of high pressure gas that can spray out onto you if you aren't careful. Work with the car outside, if it catches fire could take the garage and attached buildings with it. Wear safety glasses.

There are four studs that the pump mounts to on the adapter plate. You don't have to remove the three holding the adapter plate to the engine. Some kind of obstruction wrench, probably a 13mm universal socket, will be required to get them loose.

Good luck! Do NOT let the belt slip off the camshaft pulley or you could be looking at removing the port heat exchanger to get it back on.

Scott Clarke · Scott Clarke's Garage

I just removed my pump while leaving the stacks in place. I do have the motor out of the car, but I can't see why you couldn't pull the pump with the stacks in place.

pjh69911 · 06-12-2007, 02:49 PM

David,
You can get the pump out with a wobbly socket on the 4 bolts. Push the pump to the driver's side to relax tension on the belt, then slip it off towards the front of the car. Best to turn the crank to the F/E mark on the crank first, which corresponds to the pump timing mark. You may need a mirror to see this. It will also help when it comes time to replace the pump. Also best to uncouple the fuel lines at the pump junctions. Also, remove two fuel hoses, two oil lines and the throttle link. Then, with some luck, aim the rear end of the pump upwards, and out it comes. It took me a while to get the hang of this, but have done it many times without problems. When the pump goes back in, you have to keep the belt partially up so it doesn't get lost and you then can't find it. Good luck. Paul.

304065 · 06-12-2007, 02:50 PM

Well, access is difficult. Removing the stack on that side is six M6 nuts and wave washers (don't drop them in the throttle body!) so it takes all of five minutes to remove.

304065 · 06-12-2007, 02:58 PM

Good suggestion about lining up the belt. Make sure you turn the crank to the "FE" mark which is 40 degrees after OVERLAP TDC #1. . . as opposed to TDC #1 on the compression stroke.

david482 · 06-13-2007, 03:18 AM

Thanks for all the great info. I am curious on a number of posts and pictures folks have replaced the standard air cleaner setup with filters on top of the stacks. There is a connection from the top of the fueal filter via what looks like a valve that allows some amount of gas to flow directly into the two rear stacks, I am guessing this is part of the cold start setup? If I want to do some work and try to run the car without the aircleaner what do I do to disable this, is it all that needed since on these other setups it looks like it has been eliminated.

Scott Clarke · Scott Clarke's Garage

David-
The system you mention delivers fuel to all six cylinders. The system is activated by a solenoid on the fuel filter console. Detaching the wire from the solenoid should deactivate the system. I'd have someone help you to check, though, as you sure don't want fuel flying around.

You may find that, without the system, the car is hard to start. Mine sure was. I'm installing K & N filters at the moment, and intend to re-create the system within the new filter housings. Alternatively, manual enrichment devices are available to replace the MFI pump thermostat. I'm told that the manual enrichment is an acceptable substitute for the cold start device. It is expensive, however, hence my chosen path.