Light Gray Powder Residue On Carb Screen?

[SteveSr]

Sounds like paraffin buildup from the fuel to me.

Well, this happened from running only a single tank of fuel through a freshly rebuilt fuel system. I used the same batch of fuel a week prior in an MS260 without issue. I would think that large molecules like paraffins would get refined out of gasoline.

 

[SteveSr]

I had the same thing happen with that same saw that I took on trade, had to clean the carb screen 3 or 4 times before I got all of it.

Interesting... What kind of filter was in the saw and was it new when this occurred?

I am beginning to think that this issue is caused by oxidized plastic in the fuel tank slowly disintegrating over time. The tank material is, after all, fiberglass filled nylon which is subject to degradation. If so, the fuel mix seems to be pretty good at detaching all this crud from the walls of the tank.

 

[Full Chisel]

Well, this happened from running only a single tank of fuel through a freshly rebuilt fuel system. I used the same batch of fuel a week prior in an MS260 without issue. I would think that large molecules like paraffins would get refined out of gasoline.

I know it's an issue with diesel, but that is a much more unrefined product than gasoline...so you may be right.

If it occurred after one tankful, I would say it's almost surely from something already in the tank.

 

[SteveSr]

I now have another clue. Based on my last post I decided to try to incinerate this residue with a propane torch. The result is that only a part of the residue incinerated leaving components that would glow red but not go away. This would lead me to believe that the non-incinerated portion was actually glass fibers from the plastic in the tank. I would have thought that these shouldn't have been able to make it through the filter.

 

[grizz55chev]

I now have another clue. Based on my last post I decided to try to incinerate this residue with a propane torch. The result is that only a part of the residue incinerated leaving components that would glow red but not go away. This would lead me to believe that the non-incinerated portion was actually glass fibers from the plastic in the tank. I would have thought that these shouldn't have been able to make it through the filter.

The filter with fine mesh screen will not stop fine particulate, the felt filters do a better job with that.

 

[old guy]

Interesting... What kind of filter was in the saw and was it new when this occurred?

I am beginning to think that this issue is caused by oxidized plastic in the fuel tank slowly disintegrating over time. The tank material is, after all, fiberglass filled nylon which is subject to degradation. If so, the fuel mix seems to be pretty good at detaching all this crud from the walls of the tank.

I took the saw on trade and it had been sitting unused for a long time so I know not it's history, it is in very good condition however,

 

[SteveSr]

I took the saw on trade and it had been sitting unused for a long time so I know not it's history, it is in very good condition however,

This saw was probably shelved for carb/old fuel issues and then sat for a very long time. It was recently donated to my trail club to be reincarnated.