Recently got a stihl FS38 that was missing its carburetor. I went online and purchased a brand new one with all the gaskets and fuel lines etc. I installed the the new carb, fuel line and filter. I noticed that the primer bulb only fills about a quarter full when primed. The trimmer starts, but bogs down and shuts off the moment the throttle is applied fully. I am confused, because everything is brand new. The carb, primer bulb, fuel lines are all new out of the box. I am wondering what I am doing wrong. I am aware that the end of one of the lines has a tear in one of the pictures, I swapped it out, but the problem continues. The only way it seems to get a bit of fuel in the bulb, is by flipping the whole unit upside down, and then pressing the bulb.
we really need some photos & a lot more information
What brand carb and what model number, where did you get it from
If it was an "everything kit" from ebay or amazon 50:50 chance the carb is defective or the fuel lines are too thin and collapsing.
#3
StarTech
What confusing? That you expected that the carburetor would be perfectly tuned. They are only shipped in a will start initial setting. Most will need tuning after install, Even OEM carbs do.
But as Bert said aftermarket are hit and miss with more misses than hits. For me they were primarily misses so I quit even buying them as I got tired of wasting my time. And I am pretty sure you brought a clone as OEM don't come with all the extras. They are normally brought separately and are sold only by the local Stihl dealers.
Back to first question are you sure that the fuel lines are in the proper places? I did this before and drove me nuts but was just a mistake in line placement. The carb for sure will still need adjustments to be correct. That bulb should be filling with fuel for priming.
#5
Fish
Looks like you need a new fuel line.
Attachments
#6
Fish
It is a purge bulb, should return fuel to the tank, no need to fill, it pulls fresh fuel through the carb, purges the air out.
The fuel lines on this model are real hard to mess up.
#7
Fish
They are molded at 2 different lengths.
#8
Fish
I see that you said that you went back to the old fuel line, then try just richening the low mixture screw.
It would be the one on the top right.
You may need to pull off the plastic limiter.
#9
Fish
Also, the gasket between the carb and the intake needs to look like this one.
#10
Hammermechanicman
He may have the gasket wrong blocking the impulse hole
