[Classic30]

It's in my "runaway diesel" thread, I am now 100% sure the issue is down to the control itself, and if you don't have a diesel you might not have looked in there.

Symptoms:
- Run the engine in gear at cruising/high throttle, it'll be fine for a while.
- There is then a banging from the transmission, as if the cone in the gearbox is being slightly disengaged
- If you throttle back, it might slow the engine, you can go into neutral, back into gear and all is fine again (until next time)
- Alternatively, you can throttle back, nothing happens and if you happen to knock it out of gear, you then have an engine racing with no load at full throttle despite the lever being in the idle position.
- If you bang it back into gear (tried it today as a last resort) and waggle the lever around a bit, full throttle, idle, full throttle etc then you might get control back

Certainly sounds like a control issue to me. I'd second Faster's advice on tracking the problem, but I'm guessing you aren't getting quite enough transmission cable movement for your engine.

All this can be checked without the engine running: If you put it full forward are you getting full throttle and sufficient transmission cable travel? Same with reverse? How about neutral? If you disconnect the cable on the transmission, can you put it in and out of gear no problem?

Despite frequent use of WD40, the 'disengage' button on my old Edson control is almost frozen stiff and it's on my list of things to fix.. but the internals on these things are frighteningly complex.

 

[Classic30]

What's still confusing me is why if the gear is partially disengaging does it also affect the throttle? I get that it is going to rev higher with less or no load, but why does throttle stop responding? If it was just jumping out of gear that would be one thing, but jumping out of gear and jamming the throttle wide open is another.

There's a bunch of springs in the control mechanism and if the throttle lever actuator-thingy is disengaging from the controller's slide-thinghy.. Sorry, out of my league here!..

In other words, if the controller is kaput its possible this could happen. How old is your controller?