AFM Sticky Spot

[zKars]

Just to check if there was any correlation between which AFM’s have rivets or screws holding the cover on, I found that all of the 5 pin connector AFM’s that I have used screws, where as all the 7 pin connector-ed AFM’s had rivets.   So 75-77 with internal fuel pump contacts were rivets, then all the later ones had screws. 

I also have two turbo AFM’s and one has rivets and one has screws.  Humph. Just when you think you have a correlation…. Might just be a “where were they made” kinda thing.

I am tempted to add, “Anyone want a slightly used AFM cheap?”  I’m collecting them why?

Edited April 18, 2023 by zKars

[chaseincats]

1 hour ago, zKars said:

Just to check if there was any correlation between which AFM’s have rivets or screws holding the cover on, I found that all of the 5 pin connector AFM’s that I have used screws, where as all the 7 pin connector-ed AFM’s had rivets.   So 75-77 with internal fuel pump contacts were rivets, then all the later ones had screws. 

I also have two turbo AFM’s and one has rivets and one has screws.  Humph. Just when you think you have a correlation…. Might just be a “where were they made” kinda thing.

I am tempted to add, “Anyone want a slightly used AFM cheap?”  I’m collecting them why?

Both of my AFMs have been 5-pin so that makes sense as to why both have screws then

[Captain Obvious]

On 4/18/2023 at 9:48 AM, zKars said:

Just to check if there was any correlation between which AFM’s have rivets or screws holding the cover on, I found that all of the 5 pin connector AFM’s that I have used screws, where as all the 7 pin connector-ed AFM’s had rivets.

Thanks zKars!!

[Captain Obvious]

So I used a red Sharpie and marked the inside of the AFM where the interference was occurring. This is my target for bashing.

Here's my target to push the case back out a little bit:

And here's my drift tool. I rounded the end to try to minimize digging in and gouging the aluminum:

In position and ready for an adjustment whack:

And the clearance after a couple percussive maintenance adjustments It'still pushed in a little, but it clears the AFM vane:

So now the AFM moves smooth for the entire sweep. Next, I'm going to work on how to put the side cover back into place. The plan is to drill and tap at least one of the rivet locations along the top side. The bottom already has two screws, so I figure if I add a third along the top and silicone it into place, it should be good enough. Certainly better than the broken paperweight I started with.

[Captain Obvious]

OK, so the next step in the ordeal was a success. I drilled and tapped one of the places that used to be a rivet.

I did one of the positions along the top. Looks like this:

So now there are three screws that hold the cover on. One along the top and two near the bottom:

This is just a test fit with no sealant, so the next step will be to take the cover off again and put some silicone on the sealing surface and then screw it together "for good". And after that, put it onto the car and see what happens!!

[chaseincats]

Well done!  and let me also say that "percussive maintenance adjustments" is one of my new favorite phrases

[Captain Obvious]

Haha!   The car this is going into is running uber lean, and one of the other things I discovered while poking around with this AFM is that someone had been in there before and had adjusted the spring gear to be about ten teeth leaner than when it left the factory. I'm not sure the AFM spring is the only thing going on with the car running lean, but it's certainly something that needed to be addressed. I put the gear back to factory position and we'll see what happens when I seal this AFM up and get it back in the car.

So this AFM has clearly been messed with and abused in the past by a PO. Sticky and lean.

[chaseincats]

How were you able to know the factory gear position?  I didn’t think they were marked

[Captain Obvious]

I got lucky. When the factory set the proper position, they put a blob of silicone (or something) onto the clamp that holds the gear in position. The lucky part was when the PO moved the gear, it split the silicone blob into two pieces. One part on the clamp, and one part on the gear. I rotated the gear back such that the two halves of the silicone blobs lined up again.

I've been inside other AFM's and the blobs are gone completely. Thankfully on this AFM, the split blob was an easy way to tell where the gear  belonged.

[Captain Obvious]

Oh, and there was a round dimple dent in the gear plastic as well that lined up with the dot on the clamp.

I got lucky!

[chaseincats]

Absolutely - glad it worked 

[HusseinHolland]

On 4/22/2023 at 9:33 PM, Captain Obvious said:

Oh, and there was a round dimple dent in the gear plastic as well that lined up with the dot on the clamp.

I got lucky!

I took the front cover off mine to check the needle track - on Fiats' version it can develop carbon buildup that throws the values off at differing points of the scale. Lookig at it again, I think mine is original in terms of spring setting.  I haven't driven the car enough to know whether it's performing at it should. I do know the fuel pressure at the rail is low (30psi) once the motor has been run for a awhile, during warmup I noted 34-36psi. I'll start a thread on that when I get to testing / checking the fuel pump, etc.,.