mfi in my 69e Please help
 

So my barn find (sitting for 40 years) 911e engine and tranny rebuild is complete. The mfi was sent to a company by the engine builder, and I don't know who the mfi rebuild guy is. Once on the engine when starting the engine in the dyno room, as my builder was trying to dial in the mixtures, after a couple of minutes the plugs were totally black, too rich. He called the mfi guy who said to open up the cold start portion of the mfi which has a small plunger and piston, at least that's what I call them. He said the plunger should be out, after the car has run for a short time, it wasn't. This is designed to come by way of a hose from the heat exchanger to warm it up. The mfi guy suggested my engine builder take a heat gun and see if that will make the plunger move, thus shutting off the cold start. The heat gun worked and it made the cold start shut off. My engine builder then asked the mfi builder how he went about testing the mfi cold start shut off. The mfi guy said with a heat gun. Now a heat gun puts out far more heat than my exhaust at start up. He is not mimicking real world start ups when using a heat gun. Does anyone have an idea what my problem is? Can there be corrosion or something making the plunger and piston not want to move, without using excessive heat? Can this part be bought brand new? Can someone give me the name of a good MFI guy who would be kind enough to take a phone call on this, and possibly send it to him for him to diagnose? I don't have confidence in the guy who rebuilt it since he used a heat gun to make it work in his shop.

Thanks guys, sorry for dragging my question out so long. Stay safe!!!!!

The 69 pump is different from the later ones as it has a third element hanging off its face and I forget its purpose. I have a folder that I printed off of this site that I will be glad to go through if you can't find it. An in depth explanation of MFI by a fellow I think named Lee Rice. The session may have been called open heart surgery. Also I believe the mixture adjusters on the 69 are in reverse rotation from the later pumps. I have used Jerry Fairchild Industries and Mark Jung for pump work. You mention the cold start needing a heat gun, and I think you are referencing the thermostadt. The cold start should not play a part in the running performance unless it is stuck open. Bob

Thanks Bob. I called Mark Jung today, what a gentlemen. Talked to me for at least 20 minutes helping me out. Mark is who will be working on it, should my engine builder not be able to fix this.

Good decision. Mark went through my MFI pump and serviced the injectors, and then helped me track down a tricky fuel delivery issue. He knows his stuff.

Thanks guys, and stay safe!!!!