Recalcitrant Shindaiwa Trimmer

[Citroënbender]

I’ve had this one for years, I think the usage pattern could be described as “light professional”. Overall it’s in good condition but this morning developed a fault.

Primed up as normal, started (on choke) second or third pull, I went to put it on the grass to idle up for 30 seconds before choke off and using. As I went to sit it down, it slightly revved up and stopped.

No amount of attempts then or later could restart it, starting fluid didn’t seem to change this either, nor a cleaning and re-oiling of the filter panel. I tested the basic way (screwdriver stuck in the plug boot, grasp while gently pulling the starter cord) for spark impulse and it seems to be there.

I store these types of gear tank-down in an effort to keep the gaskets from getting too dry.

What I have now noticed, is the primer bulb never seems to fully purge the lines of air. I don’t know if this is a new or normal occurrence.

Looking for experienced input, what sort of coil readings should I expect, and if they’re within spec should I go with a Chinese carb or a gasket kit? Ta in advance for any pointers here.

[roKWiz]

Did you turn the fuel tap to off accidently like I did with a genset. Left the fuel T tap in the on position when it was last used it, so naturally did the opposite when I restarted at a later date.

Stupid things you do eh.

[Citroënbender]

Classic, have confused myself that way on countless mowers.

This trimmer doesn’t have a separate fuel tap, fortunately.

[roKWiz]

Even marked arrows on it. and missed it.

CB Mr.:4:. will know.

Edit could be a float problem. Happened after you moved it.

[Fed]

2 strokes rev up as they run out of fuel.

[Citroënbender]

That was my gut instinct too; fuel starvation due to lack of it pumping. I may have simply over-applied the starting fluid and gone too rich for ignition.

[aussiblue]

Did you store it with fuel in, or did you empty it and run it until it stopped from fuel starvation as is usually recommended in the owners handbook? If stored full of fuel the outcome is usually a gummed up carburettor.

[Citroënbender]

I have stored it fully fuelled since 2008. The only other problems I’ve had with it were directly traced to bad fuel; once drained and replaced it ran perfectly it again.

The only gumming up issues I’ve had with gear, have been from vege bar oil in chainsaws, and from E10 causing oxidisation and sticking in float bowl needle valves.

[.:4:.]

If it starts and runs on choke but dies off choke i would investigate a vaccum leak behind the carby. Last time i had an issue very similar to what you explained it was a bad carby gasket. Typically around that area it will get dirty as sitting fuel leaks a little and dirt sticks to that. Pull the carb and check the gasket. If its only a minor vaccum leak a light smear of gasket maker will get it going again.

[aussiblue]

I have stored it fully fuelled since 2008.

If it's a two stroke I bet the owner's manual tells you not to do so if it is to remain unused for more than 30 days.

[Fed]

Is the fuel tank breather blocked.

[Citroënbender]

I don’t think so, I tried to prime it with the tank cap both loose and tight. The feel of the priming bulb is somehow not right.

[snap0964]

I've got a 4 stroke mower - but my two stroke Victa refuses to die, usually the only problem it has is the spark plug - they oil up. It'll kick, run and stop. Cleaning is usually not a long term thing, it's easier to replace it, and I'm on my way. So try that.
Remove your primer bulb and make sure it has proper pressure and vacuum - the bulb can split with age, reducing both, and a split can suck air while it's running.

[foxtrot3]

Hi. A bit like my ryobi trimmer, the plastic fuel line breaks down and cracks just inside where it goes into the tank. Local mower shop or bunnings should have a repair kit with both supply (plastic) and return (Rubber) hoses and a weighted filter to go on the end of the supply hose in the tank. ( https://www.bunnings.com.au/ryobi-fu...p-kit_p3410082 ). About $20 and half an hour and you still get time for a beer after. Cheers MD

[snap0964]

Yeah, have to pick one up for my Ryobi - should fit a Walbro carby I'd say.

[foxtrot3]

Hi. That kit I mentioned up there somewhere ^^^^^^^^^^^^^^^^^^^^^ also has a primer bulb to suit the ryobi carb. Cheers MD

[.:4:.]

Originally Posted by Citroënbender

I don’t think so, I tried to prime it with the tank cap both loose and tight. The feel of the priming bulb is somehow not right.

A primer bulb isnt an expensive maintenance thing, so maybe that for a start, but i still reckon theres un metered air getting in behind the carb somewhere. Basic 2 strokes only need air, fuel and spark to run. Unless theres too much or not enough fuel, no spark or more air then that carb can deal with, it should run. A split primer, fuel line or return line will leak.

[Citroënbender]

Just for certainty, I tested the coil. Primary 0.6 ohms, secondary 5.9K. Seems good enough in the absence of hard data. It’s not a cap or breaker point ignition, just magneto like the old Victas.

Shutoff switch also tests correctly. I’m inclined to try a new plug next in case the insulator has a fine crack. If still no go, I can move focus exclusively to the fuelling.

[Citroënbender]

New plug, and off she went on the second pull.

$5.91 from Repco, very happy to have a result. Suspect a cracked insulator from rolling around in the tray.