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-   -   Engine of a different kind (https://www.the75andztclub.co.uk/forum/showthread.php?t=296697)

robbrooks 18th June 2019 10:23

Engine of a different kind
 
I know this may be a long shot, but hopefully there are some Qualcast 35s petrol lawn mower owners on here. My mower refuses to start after a long period of storage (4 or 5 years). I've changed the carburetor thinking it could be this. My carburetor linkages don't work from the switch after removing the carb. I'm now think the problem may be electrical on top of the carb linkages? How do you check for a spark at the plug? Hopefully someone on here may have one of these mowers and knows how to bring it back to life? Its never been used very much and all the belts look new!

:shrug::shrug::shrug:

Tourist 18th June 2019 10:44

Hey there, to test the spark plug unscrew it, reconnect the HT Lead, and use a pair of pliers to hold the metal part at the bottom of the plug against the cylinderhead. Now, if someone pulls the starter cord, you should be able to see the spark jump at the electrode of the plug.

I'd also check the spark plug gap while it was out.

There are some good videos on Youtube about diagnosing your mower issues - I had the same problem as you and it turned out to be corrosion of the armature. I removed it, cleaned it with wire wool and then reset the gap between it and the flywheel using feeler gauges, although you can do it by eye if you saw how close it was before you removed it. If you remove it, make sure that you put it back on the right way up ;-)

If your mower has a kill switch (or handle you have to hold up for the mower to run) then also check that mechanism as I've had issues in the past where oxidation of a copper leaf switch prevented contact and therefore stopped the spark.

If it's sparking then you've got a fuelling problem - can you smell fresh petrol in the cylinder when the plug's out?

macafee2 18th June 2019 11:33

Quote:

Originally Posted by Tourist (Post 2741481)
Hey there, to test the spark plug unscrew it, reconnect the HT Lead, and use a pair of pliers to hold the metal part at the bottom of the plug against the cylinderhead. Now, if someone pulls the starter cord, you should be able to see the spark jump at the electrode of the plug.

I'd also check the spark plug gap while it was out.

There are some good videos on Youtube about diagnosing your mower issues - I had the same problem as you and it turned out to be corrosion of the armature. I removed it, cleaned it with wire wool and then reset the gap between it and the flywheel using feeler gauges, although you can do it by eye if you saw how close it was before you removed it. If you remove it, make sure that you put it back on the right way up ;-)

If your mower has a kill switch (or handle you have to hold up for the mower to run) then also check that mechanism as I've had issues in the past where oxidation of a copper leaf switch prevented contact and therefore stopped the spark.

If it's sparking then you've got a fuelling problem - can you smell fresh petrol in the cylinder when the plug's out?

spoil sport :)
put thumb over end of HT lead and try to start mover :) ok may be not it really is not very pleasant.

Use insulated pliers not just metal handled ones. I tend to use a dry hanky

macafee2

Tourist 18th June 2019 11:39

Quote:

Originally Posted by macafee2 (Post 2741490)
spoil sport :)
put thumb over end of HT lead and try to start mover :) ok may be not it really is not very pleasant.

You only do that once ;-)

Jdwoodhou 21st June 2019 18:35

Hope I'm not stating the obvious but have you discarded the old fuel and used fresh petrol? It did the trick for my old strimmer. To test the spark plug just remove it and hold it firmly against the metal frame of the machine with the lead connected.


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