by bluemower » Tue Apr 14, 2020 10:30 am
This is the Quantum series that was produced for many years. The primer is actually a small air pump. Press the primer and a shot of air enters the float bowl. The air displaces some fuel - forcing the fuel up the venture tube. Once the fuel enters the air stream, the engine starts. Normally works well.
This system deteriorates with time.
1. primer bulb may have small holes and does not deliver a strong shot of air
2. air passage may be plugged - either dirt or residue from ethanol fuel
3. base of air filter housing has warped and primer air is leaking. This is usually caused by over torquing the screws
4. fuel level in the float bowl is too low - This results in a longer distance for the fuel to travel. Condition may be caused by a distorted float, or a leaking float. Condition may also be caused if the viton seat is distorted or swelled up. Cleaning agents (carburetor cleaner) will cause the seat to swell up causing the float to close in a lower position.
5. Bowl gasket may be deteriorated allowing the air shot to leak.
These carburetors are very easy to restore. If you see damage from the ethanol, probably best to replace the carburetor. Also replace the fuel line. These were very good mower engines. Frequently, owners would elect to buy a new mower rather than pay the repair shops to keep this going.