Leaking MFI Pump

Gavin English · 02-08-2006, 04:18 PM

Hello All,

Need some help. I own a 71 911E. Gas is leaking at the rear of my MFI pump. (a significant amount) If I turn the inginition on, while the fuel pump is priming the MFI, I can reach my hand around the back of the pump and feel fuel dripping. Since I have only owned the car for a year, I do not know what the back of the pump looks like and can't imagine where it is leaking from. (Since the pump is at the back, you obviously can't see the leak) I've searched to try to find a picture or diagram of the fuel contections at the back of the pump, but can not find anything. Basically, I want to find a picture or diagram of the lines going into the back of the pump. I can feel the fuel line from the fuel filter atttached to the pump. (So I know that is there)

Any advice or a place where I can find a picture / diagram of the rear of the pump showing the fuel conections?

At the point, I'm praying that I don't have to rebuild the pump and that there is just a loose fitting or line that disconnected.

Thanks,
Gavin

silverc4s · silverc4s's Garage

Gavin,
I am sure you will get some help here, and soon. I wish i had a photo to share with you, but I have none of the rear area of the pump, unfortunately.

Grady, Warren, Henry or any number of other experts will be "on the case" soon, I bet.

In the meantime, please be very careful with the leaking fuel situation.

An engine fire from a leak such as this is one of the leading causes of loss of these cars. Make sure you have adequate fire extinguisher(s) on hand, and have the car out doors or in a safe place when you are troubleshooting this leak.

I think there are a couple of banjo connections on the pump for fuel flow. These are prone to leaking as they age, and/or become loosened from vibration. Can you see those areas, perhaps with a small mirror & light?

Gavin English · 02-08-2006, 05:02 PM

Bill,

Thanks for the encouragement. The small mirror was my next move. I am going to buy a small mirror with an extension to reach around and look for the leak on the pump. (I know they sell them in hardware stores)

In the meantime, I was hoping the MFI Gurus would chime in with some advice. After I used the search function for about two hours trying to find some answers, looked at CMA, Haynes and 101 Projects, I had to just post the question.

Thanks,
Gavin

pickupguy · 02-08-2006, 05:09 PM

just happen to have MFI engine sitting in garage hope this helps if you need another angle let me know sorry they are a little washed out to much flash

Kerry

Zeke · 02-08-2006, 05:37 PM

I think you can see by the pics that the leak is possibly a fuel line. The pressure in an MFI line is more than the 3 or so lbs of a carb line. Exactly what, I don't know. Not as high as modern cars and certainly not as high as it is in the steel lines. You should get a mirror and a flashlight (safer than a shop light) and check to see it this is the case.

If it is, you probably ought to change every line in the car. It's not that bad of a job, just tedious in places. Be sure to use the proper clamps which are commonly refered to as fuel injection rated. They should be designed so as to not cut the soft line when tightened to spec torque. OEM is Norma, but they are hard to find. I found some at the BMW dealer and I think our host has them. They have the metric fuel line sizes you must use.

Gavin English · 02-08-2006, 06:19 PM

Kerry & Zeke,

Thanks for the pictures and advice. I'll get that small mirror and see what's going on with the leak. Those pictures were exactly what I needed. I'll let you fellas know tomorrow night what the verdict is.

Gavin

David E. Clark · 03-01-2006, 01:57 PM

Please take a look at the Ultimate MFI resources thread and add your links and resources. It will make a great resource for all of us.