Black Specs in carb bowl

[jon8christine]

Installed a new 32 36 carb this summer and decided I wanted to start playing with the jets and tuning it to run a little better without any hesitation yesterday. When I pulled the carb top I found black specs / particles in the float bowl shown here:

https://drive.google.com/file/d/1Q-95IG ... sp=sharing

None of them were stuck in any jets, but I am concerned about where they are coming from. I installed new hoses and a new fuel filter at the time of the new carb install. The fuel filter is a bypass / return type as I have an electric fuel pump that runs all the time.

Could these be coming from the fuel tank and back up the return line that looks like it's after the filter screen? Could it be carbon buildup in the engine blowing back up (I have had one or two backfires as I was tuning and setting the idle and mixture)? Seems highly unlikely, but they feel like little carbon particles. Very hard and sharp and brittle. Under my kids microscope they look like this (those are my finger print ridges for size reference):

https://drive.google.com/file/d/1x0kHFL ... sp=sharing

https://drive.google.com/file/d/1s-9TAW ... sp=sharing

[redcars]

Did you take the top off of the carb before you installed it? If not they may have come with the carb.

[18Fiatsandcounting]

Looks like DiLithium crystals that one might use say, to visit the Cygnus nebulae from the planet Zoltan XV.

I doubt they're coming from blow-back in the engine, but more likely coming from your gas tank. But I'm perplexed why the fuel filter didn't catch these?

What I would do: Clean it out, run it again, check for the particles, and if they reappear in the same quantity, you have some sleuthing to do. If they don't reappear, perhaps you're good to go.

-Bryan

[jon8christine]

I did open it up to check the float and they weren't there when I first bought it. Float bowl is cleaned and road ready. Maybe I'll put another filter after the bypass.

[18Fiatsandcounting]

Do you have one of those black plastic floats, rather than the brass one? If so, maybe it's breaking apart?

-Bryan

[RRoller123]

bits of deteriorated fuel line.

[geospider]

for investigation purposes: could use the cheap plastic clear filter: one before the fuel pump and one between the one you have and the carb.
I assume the fuel lines you replaced were in engine compartment. Only soft ones left are between tank and pump and pump to the metal lines. Gotta know if from the lines or the tank.
Agree with Bryan: how did they get through the filter you have, and even the one on the carb itself. these particles look big enough to get caught there.

for the carb. I wouldn't think you need to change the jetting. maybe the idle jet for the primary: mine is much better with a 50 vs 60 there. unless you are at high altitude.
Geo

[SteinOnkel]

Bin that fuel filter. It's obviously not doing its job.

[18Fiatsandcounting]

This has been bugging me, as those black granules do not look like fuel line, and they are too uniform.

My guess at this point: You have a problem with your charcoal vapor canister, and those granules are activated carbon that is being blown back into the float bowl through the bowl vent hose.

Whadya think guys? Could that be it?

-Bryan

[geospider]

I thought that about these specs as well. But: No fuel return or vent hose for the bowl on the 32/36. Or at least mine. Unless his lines are mixed up somehow, but then how would it run. Filters should catch these.

[18Fiatsandcounting]

Good point, Geo. But, some versions of these carbs have a bowl vent connection while some do not, and if this carb happens to be connected to the charcoal vapor canister in some weird way, perhaps some of the activated carbon "chips" are being blown down the hose into the bowl.

Just grasping for straws here, of course!

-Bryan

[jon8christine]

I bet you're right on the charcoal filter. I did tee the old charcoal filter line into the vacuum port on the carb to replicate the original setup and try to burn those fumes. I've never been into the canister, but I bet that is where they are coming from, being sucked in. I'll disconnect it and see if they return.

[jon8christine]

Looking at the canister again the bottom is to the fuel tank vent, the side is to the bowl vent and the top is to the carb vacuum line.

Do I have the canister plumbed wrong? Or maybe just not enough vacuum and charcoal is backing up the bowl vent?

https://drive.google.com/file/d/1lX1NFc ... p=drivesdk

[geospider]

Well, I think at least you found it.
I have a '79, canister goes to intake I believe.
My 32/36 doesn't have a bowl vent.
disconnect from the bowl, plug the bowl vent line. Not sure where that should go anyway. But that is because I dont have one.

[18Fiatsandcounting]

Looking at the canister again the bottom is to the fuel tank vent, the side is to the bowl vent and the top is to the carb vacuum line.

I just looked at my '71 spider, and this is the way mine is plumbed. However, on mine, the top vacuum connection goes to a "metered orifice" on the intake manifold. This is a port on the intake manifold with a rather small hole in the center bore. If your top connection is to the carburetor, I wonder if sometimes that develops positive pressure (relative to the other two connections) and pushes some charcoal down the line to the float bowl vent.

I've never taken a part a charcoal canister, but I would expect some sort of screen to keep the particles from being sucked or pushed out, but either it isn't built that way or the screen has a hole in it.

-Bryan