Mick,
My Onan engine manual only describes "hunting" in terms of a poorly adjusted or worn governor linkage as seen here:
Check the governor arm, linkage, throttle shaft, and
lever for binding condition or excessive slack and wear
at connecting points. A binding condition at any point
will cause the governor to act slowly and regulation will
be poor. Excessive looseness may cause a hunting
condition and regulation could be erratic. Work the arm
back and forth several times by hand while the engine is
idling to check for above conditions.
This is by no means "official" but my understanding of surging as used on this site is the temporary over-speed of the engine at idle when the fuel to air mix is too lean forcing the governor to open the throttle plate -- which speeds up the engine enough that the throttle is then closed by the governor and the cycle repeats. This mix error can be from a fresh air leak below the throttle plate (worn throttle shaft bushings, failed manifold gasket, or more commonly a leak in the two part intake manifold from a failing seal...) or from a plugged low speed jet. Either can produce a lean mix at idle but seem nearly normal at WOT governed working RPM. JMHO
Chuck
My Onan engine manual only describes "hunting" in terms of a poorly adjusted or worn governor linkage as seen here:
Check the governor arm, linkage, throttle shaft, and
lever for binding condition or excessive slack and wear
at connecting points. A binding condition at any point
will cause the governor to act slowly and regulation will
be poor. Excessive looseness may cause a hunting
condition and regulation could be erratic. Work the arm
back and forth several times by hand while the engine is
idling to check for above conditions.
This is by no means "official" but my understanding of surging as used on this site is the temporary over-speed of the engine at idle when the fuel to air mix is too lean forcing the governor to open the throttle plate -- which speeds up the engine enough that the throttle is then closed by the governor and the cycle repeats. This mix error can be from a fresh air leak below the throttle plate (worn throttle shaft bushings, failed manifold gasket, or more commonly a leak in the two part intake manifold from a failing seal...) or from a plugged low speed jet. Either can produce a lean mix at idle but seem nearly normal at WOT governed working RPM. JMHO
Chuck
