Anyone know about small petrol generators? Throttle mechanism particularly.

[prv]

The last two winters, Ariam's been laid up afloat where we have occasional access to power on the pontoon. This winter she's up on sticks in the yard so it's a generator job. Unfortunately my generator has been sitting unused and unloved during all that time, and now it's unhappy.

Originally it failed to start, which I've sorted by removing and cleaning the carb. Now starts nice and easily, but immediately revs up to full throttle. I don't really understand how the throttle control on this machine is meant to work, but I don't think it used to do that. It's possible I'm misremembering and being misled by the noise of starting an engine in a small shed, but surely it would start with a little throttle and then open it wider as the load came on?

The throttle butterfly is controlled by a long linkage which runs across from the carb to a fairly long arm, which in turn is operated by a small shaft protruding from the crankcase. There's a spring biassing this mechanism towards the "full throttle" position. I assume this is some sort of governor mechanism, to keep the engine turning at the right speed for 50Hz on the alternator.

The generator is this one: https://www.machinemart.co.uk/shop/product/details/clarke-fg2500-2-4kva-portable-petrol-powered-g and the engine seems to be a no-name knockoff of this Honda: http://www.northerntool.com/shop/tools/product_301_301 . The throttle/governor linkage isn't 100% identical between the two but it clearly operates on the same principle. You can see the long throttle linkage rod just above the tortoise/hare sticker - unfortunately (as on mine) it's mostly hidden under the fuel tank. The Honda looks as if it may have a manual throttle lever, which mine does not - probably due to the Honda site showing the engine as a general-purpose item whereas mine is part of a generator.

Any info on how small generator throttles / governors work very welcome!

Pete

 

[pvb]

Any info on how small generator throttles / governors work very welcome!

Loads of videos on operation and adjustment on YouTube.

 

[steve66]

You either have the springs or throttle rod incorrectly fitted . Have you at any point removed the govenor arm? If so it will definately need adjusting

 

[superheat6k]

Sounds like the centrifugal mechanism has stuck after a prolonged period of non use. With the engine stopped it will naturally set the throttle to max.

Have you tried twiddling the spigot that moves the arm to the throttle butterfly, and perhaps a generous dose of WD40.

 

[prv]

Sounds like the centrifugal mechanism has stuck after a prolonged period of non use. With the engine stopped it will naturally set the throttle to max.

Ah, of course. For some reason I was thinking it would have the throttle closed when stopped, but for obvious reasons that's completely back-arsewards. Stuck mechanism is highly likely, it's basically just been dumped in a lean-to bikeshed and ignored for the past three years.

From memory I think that gaining access to the mechanism would need either the 240v alternator or the flywheel to come off, neither of which sound like much fun. Even getting at the carb was a pain in the bum because of the surrounding frame, which takes no account whatsoever of the anatomy of the engine inside it. Is it likely that mere twiddling of the shaft will do anything? I still haven't really grasped what the internal governor mechanism consists of.

Pete

 

[prv]

Is it likely that mere twiddling of the shaft will do anything? I still haven't really grasped what the internal governor mechanism consists of.

OK, for some reason when I googled around before posting, I didn't find this video. But I have now and it's very useful in seeing how the governor works and how you get at it:



Unfortunately, if it's jammed in the "go faster" position, that means the black arm is pushing all the way in, and the pressed-steel weights are all the way in to the middle of the gear. Were it the other way round, I'd be able to press on them via the black arm, but it's not set up to be able to pull, only press.

Maybe I'll try rolling it upside down to get some of the sump oil (which I've just changed) in there. And possibly just running it for a bit might shake and/or centrifugally-pull something free (I shut it down straight away before).

If no joy then I guess it's alternator off and dismantle. I wonder if tipping it up on end would save having to drain and refill the oil (which is bloody awkward due to that frame again).

Pete

 

[idomeneus5]

hi Pete. I broke a part for my petrol genny which I bought here in Australia on that well known auction site. Exasperated and looking for advice/help/spares I came across this company in the UK. "generator guru" ph. 18556004765 . They were most helpful and even had the part I needed. their business card says to ring for parts and/or advice,
"www.generatorguru.com" hope this may be of help, cheers Peter