Woodboss 028av. I removes the air filter. on the left side there is a tiny plastic tube with a tiny spring inside it. what is this for

SOURCE: Stihl Super Wood Boss 028AV sputters but won't run

sounds like the fuel pump is bad in carb get a carb kit and rebuild it and check the fuel line from carb to to the filter in tank and if that is a two stoke eng with oil in gas do not run on ether will most likely burn up eng

SOURCE: Echo pole saw boggs aand wont reach high rpm. I

If you must choke it for it to run it is lean. Have you attempted a carburetor adjustment? Start with "H" and "L" at 1.5 CCW from lightly seated. Then try this:
Carburetor Adjustment by Madsens.com
http://www.madsens1.com/saw%20carb%20tune.htm
CW is leaner; to lean will destroy the saw. If over tightened closed (CW) the adjustment screw faces are easily marred; marred adjustments are difficult to impossible to set properly.
Clean the air filter; adjusting with a dirty filter can cause a run lean condition once cleaned and the saw run.
There are 2 wav (sound - idle & full – not highlighted) files that I find most helpful, I think you will too.

An air leak where the carburetor bolts to the engine or the intake manifold can also cause this. If an adjustment does not or has not fixed this I suggest you try your friendly neighborhood Stihl shop. Explain everything you have done to a mechanic there. Good saw shops pressure test the crankcase, fuel lines, and intakes. They have test equipment homeowners do not. Explain what you have already done and ask for a repair estimate. I think you will be pleasantly surprised. Not all small engine mechanics are created equal... why I recommend Stihl. The odds of finding a good mechanic at a certified Stihl shop are in your favor. If not already using 50:1 fuel mix, please ask the Stihl shop what they recommend. Echo on their site has a statement equivalent to "regardless of what your manual says use 50:1". HTH
Lou

Testimonial: "Thanks for the advice. I dont see any adjustment screws for high or low on this carb. Its on a ppf 210- Echo power pruner"

SOURCE: ryobi chainsaw pcn4040 - oil not being pumped onto

C. Both A and B. Is it the original bar? Has it ever worked with this bar? Yes continue, no reply below (first). Is there an oiler adjustment?
I know you did this, I have OCD. Good on you for checking.
Oil System Plugged:

1. Remove the clutch cover, bar, and chain, clean the bar groove, any holes and passages on the rear of the bar (both sides, consider rotating the bar), if equipped with a sprocket nose ensure it rotates easily at least one complete revolution. Clean the saw oiler hole and channel. Insert a blunted, hooked piece of wire through the oil filler hole and pull the hose in the oil tank out. Pay attention to the screen or filter on the free end (clean or replace, difficult to determine serviceability). Start the saw and see if it oils when revved up (oozes down side of saw). If yes reassemble your saw. If no, continue with 2.
2. Work your way through the linkage (use IPL to identify components and locations) cleaning and replacing any defective parts as you go. Carefully check the hoses for cracks especially at bends and connections. If equipped with an oil pump it is usually behind the clutch (clutch is a left handed thread). Please make extensive notes & some digital pictures will help during reassembly.

SOURCE: How to remove plastic limiter cap on (H) carburetor adjustment

If plastic cap is present, it should just pop off with a thin sharp hook. Look carefully at the screw heads--they may be 'D' heads which require a special screwdriver and are supposed to keep owners from moving the screws (thank the EPA for these). Only authorized saw servicing dealers have access to these tools and therefore are the only folks allowed to adjust these saws. Being nonconformist, I made my own by drilling the center of a 1/4" rod, sawed off one side somewhat and welded a flat across the cut. Hope this helps!

SOURCE: I need a diagram to see how to replace the fuel

The large hole in the tank brings a line from the filter to the upper carburetor fitting. The lower carburetor fitting goes to the primer inlet (which is found by plug and try). The short line from the tank goes to the outlet of the primer. With fuel mix in the tank, try one of the ports in the primer with the line from the carburetor. If correct, the primer bulb will fill with fuel--otherwise, try the other primer port and see if fuel will come into the bulb. This may take over 6 pumps if the carburetor is empty of fuel. Did you check the fuel filter for plugging? If it was ok, and with new lines, fuel should pump into the primer provided the carburetor is not plugged itself. If the problem seems to center on the carburetor, be sure to check the diaphragm in the lower chamber for flexibility--no holes or cracks. Also, there is a very small filter screen in the mid-body section that may be plugged. Use spray carburetor cleaner to clean the carburetor inside and out. When you get fuel to come into the bulb, the short line from the tank goes to the empty port. Hope some of this helps!