20 Most Recent Husqvarna 28cc Hand Held Blower HVH 125B - Page 9 Questions & Answers

No, check that the two fuel lines are not switched and fuel purge is working.

Easy way to test; Identify which line has the filter and disconnect the other (fuel return) at the carburetor. Then press purge bulb several times. Fuel should spurt out the fuel return port at the carb.

If no fuel spurt, move fuel line (with filter) to the other carb fuel port and repeat test. If still no fuel then purge is not working... either fuel not delivered from tank or carburetor is blocked or bad diaphragm or other.

If it sat out in the weather all winter it may have rusted the actuator shafts.

If it happened suddenly, then more likely a stick has lodged underneath or something has come apart and jammed both the clutch and the forward reverse actuators.

it must have a loose bolt under it

My thought would be immediately sheared flywheel key, it is easily done to not enter the key in the flywheel to the recess in the crank, the key is alloy and part of the flywheel itself.

drive shaft possibly broke the end off or the gear box at end has failed

Fundamentals

1. FUEL
2. COMPRESSION
3. SPARK

A simple diagnostic shortcut is starter fluid. Remove air filter and spray a short burst (1 second) of starter fluid directly into throat of carburetor. Promptly attempt to start.

If it runs for a couple seconds and dies, then compression and spark ok but fuel delivery is not. Check fuel lines and filter inside tank.

If no run, then conirfm spark and compression.
Remove spark plug and hold electrode end against the cylinder and pull starter cord. You should see a spark.

To test compression, spark plug removed, place thumb over spark plug hole and give starter a pull. The compression should push your thumb and make a PFffft sound.

I am unfamiliar with the model but taking a guess; the drive belt could be slipping when it picks up something. It would be a good idea to look underneath to see what those sticks and stones might be getting stuck on instead of being thrown clear and check the drive belt for condition and tension.

check for spark and fuel flow.

The air gap should be as close as possible without touching, bearing in mind the flywheel will grow as it warms. I don't know the recommended gap for that engine but I usually set them to 0.008" and find that works ok.

Carburetor setting should be done by a dealer and by using a tachometer. However, to get a ballpark setting. Turn the screws in until they lightly seat, then turn the "H" and "L" screws out 1 1/2 turn. Then have your local dealer finish setting the carb.

Could be any number of things. Fuel, fuel filter, fuel line, fuel tank vent, fuel impulse, carburetor, intake leak, crankcase leak (shaft seals).

Try to push in and hold the freewheel lever and rock the mower forward and backward. The bypass should click shut and the transaxle re-engage.

I don't know, the specifications page doesn't give much technical detail at all. The compression pressure at starting speed of a 2-stroke is lower than generally expected due to the engine capacity growing at a certain speed due to reflected exhaust pressure waves effectively blocking the exhaust port. A too-high starting compression would result in fuel detonation at speed resulting in piston damage, something many motorcycle owners discovered the hard way in the early days of high performance Japanese bikes. I would be content with around 100 psi but the real test is how the engine starts and works...

Possible seat switch. Try rising out of seat and sitting down hard. If problem abates then replace seat switch. On this model I believe you can disconnect the seat switch and it will start and run (there won't be an operator not in seat safety, so reconnect after testing). Disconnect seat switch and try moving levers and see it problem goes away.

The user manual usually describes the adjustment process fairly well and usually it works well on a new or nearly new machine but not so well on older machines. The typical carburettor has three screws being the throttle stop adjustment for the idle speed, a mixture screw for low speed and one for high speed - by the time a machine has aged enough to need adjustment, getting it right is nearly impossible and getting it near enough to do the work is the main aim. From the position the screws were in when the machine last run well it is important to note 1/8th of a turn at a time is the sort of adjustment needed. Adjust the low speed screw for a reasonable idle and then up to working speed to adjust the other for smooth running, or at least that is the theory. The trouble is adjustment of one screw has an effect on the other which means a deal of patience toing and froing between the screws until a balance is reached...

https://www.amazon.com/Husqvarna-carburetor-576019801-fits-223L/dp/B00YSJJ3BG

https://www.youtube.com/watch?v=Jq3P6qjaKJ0 This video will show you how to adjust the air/fuel mixture and idle.

Carb idle mixture and idle speed adjustment might do the trick or it might need a carb stripdown and clean before readjustment. The carb diaphragm can be affected by long immersion in fuel and lose flexibility and in that case replacement is advised. There is a small chance the vacuum pulse from the engine crankcase isn't strong enough to keep the carb supplied with fuel at low rpm. This isn't unusual and usually happens when a 2-stroke engine has been idle for a while, such as over winter. It was running fine last season but now it simply won't behave. In that scenario it is possible the crankshaft seals have lost flexibility and air is being drawn past them reducing crankcase vacuum...

https://www.youtube.com/watch?v=jsDNRbfFxj4 This how to video should help you.

Test run without the blade so throttle response can be determined.