Engine inhaled charcoal!

[Psycho_Bob]

I have been driving my '81 Scottsdale with a 305 to school and back pretty often, and it has been running perfectly.  All of the sudden it starts acting like it is starving for gas and won't idle.  I pop off the air cleaner and find that the middle of the air cleaner inside the filter is covered in fine bits of charcoal.  From the best i can tell, something let go inside the canister and it sucked right in from the hose that feeds from the canister to the air cleaner.  I shop-vac'ed the charcoal off the top of the carb and dumped it out of the air cleaner.  I also changed out the fuel filter in the carb, and added an inline fuel filter just for good measure.  With all of this done, it still acts the same.  Any help would be greatly appreciated.

[ccz145a]

air filter too. how fine were the particles.

[jefferias]

me personally ---would pull the carb off and inspect it at the very least. also would look in the intake. maybe a rebuild of the carb is a good idea anyways? get a new canister as well if not done already.

[VileZambonie]

It's probably mouse turds. 

But if you have garbage that is in the air cleaner how did it get in there?

[Psycho_Bob]

It is definitely charcoal in there, I can actually pour it out of the hose going to the canister.  I will probably pull the carb and intake manifold off this weekend, since I need to change out some lifters anyway.  What should I look for on the quadrajet, as far as things that commonly plug up or otherwise cause problems?

[ccz145a]

I once put an 50Gal external aux fuel tank on a 79 model, operated it from a manual valve mounted on the drivers side below the seat. Anyway, the system had a return line so when you were running on the aux tank, the return line would fill up the stock tank, and if you didn't pay attention would overfill the stock tank a cause overflow to the vapor canister.
Now, at this point, the canister would start dripping fuel on the ground. It is possible that it could have filled the vacuum lines with fuel/charcoal slurry, but I didn't let it happen very often and it never caused the problem you describe.
I could see that fuel in an topped-off tank on a hot day could expand and find it's way into the canister, though.

[Psycho_Bob]

I tried putting on a new electric fuel pump on the truck with no effect.  Tried reconnecting mechanical pump with only slight improvement.  Replaced carb fuel filter and added one inline with no improvement.  Blew compressed air through the hard line back to the tank to clear the screen in the tank if there was one with no effect.  (BTW take the fuel filler cap off if you don't want a pressurized gas bath like I got) I ended up leaving the electric pump inline with the mechanical and just driving it to autozone for a rebuild kit for the carb, and all of a sudden something broke loose and it went from 45 to 85 pretty much instantly and has been running perfectly since.  A lot of troubleshooting to just drive out of a problem.  On the up side though, I found that my lifter problem turned out to be the heat valve on the exhaust manifold ticking in time with the engine, since someone pulled the check valve out of the system.

I also took the charcoal canister out of the system with some creative rerouting.  I wasnt sure what to do with the line to the pcv valve so it is still open,but I took and looped the big line from the carb to that port on the air cleaner where the charcoal came through.  All of the smaller lines got taken out and capped.  Should I plug that pcv line since there is another line on a different port on the pcv valve?

[VileZambonie]

PCV line? Are you sure it isn't the canister to bowl vent? Why don't you take a few pics.

Why do you have an electric and mechanical fuel pump? 

[Psycho_Bob]

The dual fuel pumps is basicly because I didn't bother with crawling under the truck to unhook the electric one after it started running well.  At some point I will end up taking it out, but I am not overly concerned about it right now.  The canister to bowl vent was the line that I looped back to the air cleaner.