Will, I finally decided to do some pump mods this weekend. When I removed the AFC top cover, the diaphram had this dry black "dirt" on it. Where could this have come from? I'd guess there was almost half a teaspoon of it.
At one time I did have a cracked boost line, could dirt have been sucked in? Is it old coked fuel? Any ideas?

 

If it was a very fine powder then it's probably particulate matter that just went through your air filter. It's not a HEPA filter so fine particles do get through. They tend to collect in places where the air doesn't flow like in the diaphragm.

Edwin

 

The consistancy was more akin to freeze-dried coffee. Sizes range from about a sixteenth of an inch to powder. Is it possible for oil or diesel to be sucked into the manifold and then into the VE boost line?

 

It's possible for the fine powder to clump into granules if there is any moisture at all which there can very well be because of the compression. If it is easily crushed back into a fine powder then I still lean toward my original theory.

If the granules are very hard then you may be looking at something else. I'd clean it up and see if it returns. If it does then look for a leak between the compressor intake and the air filter. When you're making power the system is almost always under pressure past the compressor but when at idle I think it might be possible to suck in dirt elsewhere.

Oil will stay oily and I think diesel will also so your powder would be wet. It IS possible to get oil in the intake if the turbo return line is plugged but that would probably manifest as an engine runaway and if diesel fuel were getting there you'd have a possible runaway condition also. (Assuming you meant the crud was on top of the diaphragm)

I have found similar dirt in cruise control systems that had filters on the air side of the vacuum diaphragm. You'll probably find similar dirt in other air systems as well unless they use an HEPA filter.

Most paper filters only trap the big chunks. You can probably do a google and find particulate size specs on them but I'm to lazy.

Edwin

 

It's probably a carbon/oil mix. I've seen that in a couple trucks. There's usually some rusty powder from the smoke screw in there too.

 

wher is the fuel pin and smoke screw how do i do this mod i hav a 91-92 12 valve w250

 

im trying to find out how to mod my pump smoke screw?fuel pin wher is it i need help i puld my diephfram off is the pin on that i have a 91-92 w250 12 valve

 

Welcome sixgun4x4.
Go to the top of the page and look for this.
"How do I...?" Look here first! A.K.A. "The Sticky"

There is a lot of good info in there, Scroll down 2/3 of the page to Performance
This will answer a lot of you questions.


Flash.

 

thanks for geting back