[Jonny042]

Indeed I have been hibernating.... well, skiing, actually!!! Haven't strapped boards to my feet in 27 years but it's all coming back to me..... I remember now why I went skiing 2 or 3 times a week when I was young!!

I'm sure you'll find the help you need here! And wouldn't be surprised if you can get this thing running just fine - somewhat dependent on how much you're willing to attack the pump by yourself.

OK, on to the diagnostics...... alarm bells go off for me when I see that the rack won't move with that bolt threaded into it - that's a problem, at least it would be on a 911 pump. Does the Merc pump have any sort of zero throttle deceleration fuel cut like a 911? On the 911 the rack is free to move towards the lean direction when the solenoid presses on one of those linkage arms. So with that bolt you'd be able to move a 911 rack for sure.

I see that the arrangement of the linkage arms and cold start enrichment is a bit different, too - I guess that the cold start arm can be seen at the top of one of the pics - does it have some effect on rack movement?

That #2 piston is probably gummed up a bit but not too seriously - if you flood the fuel chamber with some sort of injector cleaner or penetrant and work that plunger up and down you should be able to at least get it working like the others.

I don't see anything wrong inside the pump or with the space cam. The zero throttle "meaty" portion of the cam is the idle area and the stylus is lifted to reduce fuel at idle. It drops to increase fuelling as the space cam moves clockwise with the throttle.

As you increase throttle I would expect some rack movement but it is relatively small. But still should be measured in mm, not hair widths. If you can manually move the flyweights outwards against spring pressure, as though RPM is increasing, you should also see some rack movement.

If not, I'm going to say there's likely something awry/stuck in the linkage, or perhaps that gummy #2 plunger won't rotate in its bore (which is the movement which increases or decreases fuel delivery) is keeping the rack in place when it should be allowing the rack to move and change fuelling as the car warms up.

Come to think of it the gummy #2 plunger (and perhaps several others not moving freely) are the most likely culprits from sitting for so long.

Hope that helps!!! Don't be too scared to poke around a bit more the MFI pump isn't actually that delicate, and there aren't too many things that you can mess up at this stage provided you don't take it apart too much further. Even then, if you are careful to put things back where you found them you can't do too much harm. However don't loosen the clamp screws of the 6 collars that index the plungers to the rack as you'll absolutely have to have the pump re-calibrated.

Working ahead a little bit, but once you get the rack moving freely you can work on priming the pump head with gasoline and injector cleaner, and checking that the plungers are all delivering fuel and that the non-return valves (check valves) are working, then hook up the lines and injectors on the bench and spin the pump with a drill so you can test the fuel delivery off the car.

Fun stuff! It's such a neat system, and even though it's pretty sophisticated, it's actually made up of simple parts. Levers, gears, cams, springs, pistons, etc. all stuff you can see and figure out.