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I have a SH86 blower that last lost power and barely would blow any air.
I cleaned the air filter, installed a new fuel filter, installed a new spark plug, Changed out the fuel and put a little Seafoam in the new fuel. Noe of that helped, so now I a=m asking what did I miss, or do I have to dissasemble the engine to locate the problem?
Any good thought on what direction for me to take on this?

What did the compression test show? Wondering if it had just
enough compression to start and run but not enough to do the
job.

I do not have a compression tester, so I do not have an answer. I tried it today and it seems like it is not getting enough fuel. Maybe a carb problem? I do use straight gasoline, no ethanol gas in my small engines. It started easy but as you said did not run enough to move the air, and then it stalled. I did put some more Sea Foam in the fuel tank and shook it to mix. I am thinking about taking the carb apart and checking it out. I need to get a repair kit for it first. I am sure it probably has a Welch plug/cap inside the carb.

Blower carbs have a tendency to come loose on the manifold and leak air
But You now have me worried whe you say you are using strait gas.
This is a 2 stroke engine that uses premix fuel.
Carb is a zama C1M S203A
In the USA you can only buy a complete replacement carb
AFAIK all C1M-S??? carbs use the gnd-88 diaphragm & gasket set and most use the RM-155 rebuild kit \
Stihl bought Zama a while back and delisted most of the Stihl parts .
However in the EU they were not allowed to do that so EU parts suppliers list the individaul part numbers
See DIY Spares Note they list the STIHL part numbers for the internals
Now if you search those part numbers you usually come up with the correct kits.
Most of the kits sold on Evilpay & Scamazon oddly enough are correct as there is only 3 factories ( apart rom Zama ) who make these parts
If you are unsure then pull the carb apaprt & photograph the gaskets & diaphragms
Yours should look like this gnd-88
Zama identify their pump diaphragms by the extra holes which in this case is only 1, as 2 are used for the locating pegs & one is used for the screw

Check the fanwheel, make sure it is running the same speed as the engine. It could be slipping.

ChiefH said:

I have a SH86 blower that last lost power and barely would blow any air.
I cleaned the air filter, installed a new fuel filter, installed a new spark plug, and checked the spark arresting screen. Changed out the fuel and put a little Seafoam in the new fuel. Noe of that helped, so now I a=m asking what did I miss, or do I have to dissasemble the engine to locate the problem?
Any good thought on what direction for me to take on this?

Click to expand...

remove exhaust and run is power restored? whilst the exhaust is off you can look for piston scoring.

Ok some information: First the fuel I use is gasoline (without ethanol) plus the silver container of Stihl oil, mixed 50:1. I bought a compression gauge and checked the compression. After three pulls it was 85-psi, and after 4 pulls it was 100-psi. I have not found any specifications for the normal pressure. I have ordered a repair kit that is a replacement for RM-155. When I push the priming bulb, it brings up fuel each time, so I think that the supply line from the tank to the carb is most likely sound. I will check the tightness of the carb attaching bolts.
Tomorrow I will check more stuff on the engine, and try to remove the muffler for inspection.

First to all who offered some great suggestions, Thank You. Yesterday was my birthday, and today I got my present: I took the spark screen out, and put the muffler (minus the screen) and the rope side of the blower back on the unit. Pushed the fuel bulb a bunch of time and pulled the starter rope and bang-O it started on the first pull, and ran with authority. So my problem was the spark screen was extremely clogged with carbon. Now I am trying to get it clean. I have tried PB-Blaster solvent and used a brass bristle brush. I also tried Brake Cleaner, and Small Engine Carb cleaner. They all take a while to loosen the carbon build up. I am now soaking it in a mixture that is mostly PB Blaster. I will take a steel bristle brush to the outside of it tomorrow. I most likely will have to use a small nylon brush on the inside.
Is there any other way to get the carbon out of the spark screen? One that is easier?
I hope my description will help someone later on.

Burn the carbon off with a propane torch. Search videos on youtube.