stuck CSI sensor plate and lever

[jstith]

How does one fix this problem? Do you have to remove the mixture control unit and adjacent assembly to do it?
'76 911S'er

[john walker's workshop]

If the piston is stuck in the fuel distributor, the sensor plate will not move either. Take the FD off and grab the tit on the bottom of the piston with visegrips and carefully try to get it to move. Spraying penetrant around it from both ends can help, but clearances are minute. There is usually a tit on the piston, but if not, disregard, because you can not damage the piston in any way. Don't even take it out all the way if you get it moving. Just move it in and out so it's free and reinstall the FD.

[jstith]

Thanks for the advice; I'll try it.

[HaroldMHedge]

In my 82 SC, the sensor plate was sticking and not moving smoothly i.e. not bouncing during the bounce test. It turned out to be that the grease for the pivot pin had dried out. After cleaning and applying new grease the sensor plate operated smoothly and and bounce as it should. The Haynes manual covers disassembly of the mixture control unit in the Supplemental section.

I was able to remove the mixture control unit for this repair without dropping the engine.

[boyt911sc]

Originally Posted by jstith

How does one fix this problem? Do you have to remove the mixture control unit and adjacent assembly to do it?
'76 911S'er

There are three (3) screws that hold the FD to the metering unit. Two (2) are exposed and readily accessible. But the 3rd. screw located at the front is directly under the control fuel line. This line including the adaptor have to be removed too.

After removing all the 3 mounting screws, lift up the FD and place a hand under it just in case the plunger slides out. In this scenario, it could be stuck. So just be ready for any surprises. The last thing you want to happen is dropped the plunger to the floor and damage it.

Now, time to inspect the condition of the fuel distributor. A good FD will have the plunger moving or sliding in and out of the barrel with minimum resistance. I use a magnet to test the fitment. If you need a plier or a vise grip to make the plunger slide, that is a sign of trouble.

If it is really stuck, a vise would not be enough to get it to slide out. Keep us posted.

Tony

[jstith]

Thanks to all!
John

[john walker's workshop]

The visegrip idea is to free it up. Once that's done, reinstall it. Done itmany times. If you can't free it, then different story.

[jstith]

I couldn't get it out with a small vice grip and thin needle nose pliers and it didn't loosen with WD40 and putting a small dowel against it and hitting it with a hammer. Do I need to take the mixture unit apart?

[boyt911sc]

Originally Posted by jstith

I couldn't get it out with a small vice grip and thin needle nose pliers and it didn't loosen with WD40 and putting a small dowel against it and hitting it with a hammer. Do I need to take the mixture unit apart?

jstith,

The problem is the stuck FD plunger/piston. After you removed the FD from the AFM unit, the sensor plate would be free to move. Test and confirm the movement of the sensor plate lever. Keep us posted.

Tony

[john walker's workshop]

You would have the same stuck piston problem with it apart as together. At least there's something to put in a vise and patiently work on it. Maybe bigger VGs or maybe grab the tit in a vise and then try twisting the body back and forth gently until you feel movement.
Immersing the whole thing in a mild solvent like mineral spirits for a week might help.

[reclino]

I just rebuilt my 1986 930 cis head, had to take it to bits and carefully hammer the piston out with a brass punch. Had been soaking it for a while in clean mineral spirits. Once out and ultrasound cleaned it was like new.

I used a Dremel and ground the jaws of a pair of vise grips to fit the tip of the plunger, but even then it would not budge.

[E Sully]

Originally Posted by HaroldMHedge

In my 82 SC, the sensor plate was sticking and not moving smoothly i.e. not bouncing during the bounce test. It turned out to be that the grease for the pivot pin had dried out. After cleaning and applying new grease the sensor plate operated smoothly and and bounce as it should. The Haynes manual covers disassembly of the mixture control unit in the Supplemental section.

I was able to remove the mixture control unit for this repair without dropping the engine.

It would be a good idea to take apart the air metering unit and clean and re-grease the pivot point, as well as taking apart the fuel distributor to free up the piston. WD40 is not the best for this, a good penetrating oil will work better.
It is easier to get the penetrating oil to the piston, and to carefully push out the piston when separated.
There are fuel distributor re-build kits available on ebay. They include o-rings and a new joining plate. Some kits include the copper sealing rings for a bit more money. It can be a bit of a challenge keeping the o-rings and metering slits in place when assembling, but I did not find it that difficult.
You can do it yourself if you want to try. If you have problems, or do not feel confident enough to do it yourself, there are a few members on the forum that can do this for you.

Metering plate pivot.


Fuel distributor


I have cleaned up a couple old ones I bought as backups for my 1st year 1973 CIS.

[manbridge 74]

I have also successfully returned these to functioning well. Ive used a heat gun to heat up assembly until it was almost too hot to touch. Helps a lot.

[Walt Fricke]

On the other hand, after you have put it back together, it can leak. Had that happen to me. Not sure why. I don't know just how to pressure test it without putting it on the car. Removing and installing with the engine in the car is a bit tedious.

I'd be inclined to exhaust all in place options first, and then all off the car options, before separating the two halves.

[boyt911sc]

Originally Posted by Walt Fricke

On the other hand, after you have put it back together, it can leak. Had that happen to me. Not sure why. I don't know just how to pressure test it without putting it on the car. Removing and installing with the engine in the car is a bit tedious.

I'd be inclined to exhaust all in place options first, and then all off the car options, before separating the two halves.

Walt,

That is what a CIS bench tester will do for you if you don’t use your car to test the fuel distributors and warm up regulators. Like everyone else, we started using the car to test and verify that the parts are good and working. As I started to do more testing, it was imperative to build a dedicated set-up to free up my ‘78 Targa followed by an engine test stand.

After an engine rebuild specially a CIS , I find an engine test stand very helpful and convenient in my start ups. The accessibility and comfort a test stand gives you is an advantage you won’t have with the motor installed in the car. Specially when you get older and not flexible as you used to be.

Tony

[Walt Fricke]

Tony - between being an engineer, and a retiree with a small business based on 911 engines, you are in a special position vis a vis many of us, who only work on our own cars - even if we have done more work than perhaps we would have liked to, and some of which we caused by our own mistakes.

I have a couple of spare brake master cylinders, which would work fine as a home brew CIS injector tester with the addition of a pressure gauge (inexpensive), some plumbing, and some welding and fabricating. But I just squirt a fluid into the injector, put the air hose rubber nipple on it, and look at what comes out. Or buy new ones. Not quite enough need to build a tester.

I expect one could use a fuel pump (I've got a couple of used ones as spares) and some plumbing to pressure test a rebuilt FD off the engine. And test the WUR - I suppose it would make sense to test the two together, and not much more complicated.

If I built engines for others, for sure I'd make a test rig for running the motor. Especially if I did the work in my basement!

[mikedsilva]

Originally Posted by E Sully

It would be a good idea to take apart the air metering unit and clean and re-grease the pivot point, as well as taking apart the fuel distributor to free up the piston. WD40 is not the best for this, a good penetrating oil will work better.
It is easier to get the penetrating oil to the piston, and to carefully push out the piston when separated.
There are fuel distributor re-build kits available on ebay. They include o-rings and a new joining plate. Some kits include the copper sealing rings for a bit more money. It can be a bit of a challenge keeping the o-rings and metering slits in place when assembling, but I did not find it that difficult.
You can do it yourself if you want to try. If you have problems, or do not feel confident enough to do it yourself, there are a few members on the forum that can do this for you.

Metering plate pivot.

how does the metering plate pivot arm remove from the body? I've got the circlips off, then the cover plates popped out, and on 1 side there was a spring and a ball... the other side looks to have just a ball but it doesnt come out... does the centre pin get punched out?

Never pulled one of these apart before and dont want to damage it, but this one is pretty gunked up...
Mike

[Schulisco]

Refer to Haynes Repair Manual for the 911...

https://us.haynes.com/products/porsche-911-65-89-for-coupe-targa-cabriolet-haynes-repair-manual?variant=46929898701050

[mikedsilva]

Originally Posted by Schulisco

Refer to Haynes Repair Manual for the 911...

https://us.haynes.com/products/porsche-911-65-89-for-coupe-targa-cabriolet-haynes-repair-manual?variant=46929898701050

got it apart ok.
cleaned it all and seems fine.
I reassembled and realise only 1 side has the spring. My operating lever rotated smoothly ( i oiled roller and pivot shaft with engine oil) but the lever can move side to side which isn't right... not sure i put the spring in the right side or maybe it's caught up.

Will pull apart and check my work...

[Schulisco]

The Haynes contains an exploded view of it... there you can see all its parts...