XL-903 Who needs a good laugh!

[MCS]

I picked up a couple of XL-903s last year. One I used for parts to fix an XL-800 and the other is just a work saw. I ran the work saw a little last fall and I didn't think it had any major problems but it did need something - it just didn't run quite right. The weather is getting warmer so it's nice to be outside. I grabbed that 903 to see how it would run. Well, it didn't run. I could prime the carb and get it to fire but that was it so I pulled the carburetor and opened it up but it looked really clean and the two diaphragms didn't seem all that bad so I put it back together. I pulled the fuel line out but it was really stiff so I replaced it and the filter. It had a "non-Homelite" filter - all plastic one - but I had a small diameter metal core filter handy so I stuck that on the hose and I made sure my new piece of Tygon was long enough to reach the bottom of the tank.
It took a little while to get the carb. primed but once running it ran just like 5.0 cu in saw should. I made four cuts through a test tree and it died. It would kind of idle but no high speed.
I lifted the top off that HS Tillotson What is all this brown goo?
I had to pull the carburetor........

This picture is the metering chamber so all this came past the needle valve.
I dumped the gas into a glass jar but it didn't look all the bad so I pulled the filter out. That filter was perfectly white when I put it in
The bottom of the tank had an inch or so of the brown goo. It is not very gas soluble. I tried rinsing the tank with gas and then paint thinnner but both poured out pretty clear. I tried soaking the carburetor parts with a few different things but the only thing I found that seemed to affect it was some choke and throttle body spray cleaner.
I just can't imagine how the fuel pump pulled that stuff through, especially past the filter, but that carburetor was clean as a whistle when I put it in the saw. The goo reminds me of Permatex Form-a-gasket.
I don't know if the carburetor body can be used. The main jet may be plugged tight.

[chainsawwhisperer]

Yuck! That stuff is nasty! I wonder what the heck it is?? Is it water soluble? If so, Maybe water got into the tank and reacted with something??
I have seen fuel lines completely turn to a jelly like goo, and the only thing that would touch it was carb cleaner. But I have never seen them turn to liquid goo! That's a weird one for sure.
Jim

[MCS]

Sometimes you just have to keep it simple. I got a can of hot water and some Joy dish soap and dropped the carb. in it. A little soaking and a little brushing and all that stuff came off ;D. I'm still going to have to drill out the welsh plugs. This carb is actually an HS1 from an XL-12.
As far as the saw goes, before I tried the above, I had sprayed and rinsed the tank with carburetor cleaner several time and got it pretty clean. Put on a new filter and the original carburetor, an HS103. Saw ran great , made lots of cuts on a down tree, brought it back to the shop and lifted the top plate to check the inside of the carb. and it was clean.
In the plastic pail that has all the rinse from the gas tank, all that goo is on the bottom and the solvents are above.
Thanks Jim for reminding me to try something simple

[RBW]

Believe it or not, that black goo is a fuel line from days gone by. Ive cleaned lots of that gooey black crap out of tanks before, but Ive never seen it get up into the carb like that.


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[topgut]

Great Post MCS. Never thought that crud could make it to the carb. WOW!