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Solved - Lawnflite 478sp rotary only runs without air filter

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Concept2 Sat, 19/11/2016

Edit for future searches - I cleaned the carb in the ultrasonic.  However, despite appearances to the contrary the paper filter was "blocked".  I thought i had tried another but clearly had not - i popped one on from another machine and it ran fine.

My conclusion is that the previous operator had tipped it over carb down to clean the deck and in doing so soaked the air cleaner in fuel.  The machine was then run in a choked state and  oil/fuel then ran on the deck which is how i found it.

 

Hello all

This is not an oldie but hopefully one of the experts can assist as my usual methods have drawn a blank so far...  Please bear with the background.. 

I have the dubious pleasure of looking after the mowing equipment for our model plane club - this is important as others use the kit and for this situation i think it may have some bearing on the current situation..

Mower is a 21" Lawnflite 478sp and has been in good heatlh and is used infrequently as we have a small tractor for the main mowing.. The tractor was out of order and someone has used the rotary to cut the patch so it had a good session. No report of a problem albeit if it runs (however that maybe) it would be deemed ok!  

Sometime after this usage i came to use it and it was in poor order and it ran but sounded like the choke was on.  It appeared to have black oil on the deck maybe it had been blown out from a breather?

I changed the oil and it appeared in poor condition - hard to tell if it had fuel in the oil.  It starts readily but sounds as if it is "choked".  If i remove the air filter it appears to run OK both at idle and in use. (filter is paper type with blue foam surround)  I have removed the carb, float bowl and blown it out as i normally would for a poor runner and it is still the same.  Clutching at straws i swapped the filter for one from my Hayter - still the same.

It has a red primer bulb with what appears to be a small hole in the Centre - i believe it has always been like this.

I would welcome any suggestions,

Chris

 

Forums

wristpin Sat, 19/11/2016

The fact that it has had oil on the deck suggests that it may have been tipped on its side and the that the carburettor float bowl may be contaminated with engine oil.  Rule of thumb is that you only tip the mower back on to the handle bars with the spark plug pointing skywards. Is the paper element air cleaner stained with oil?

Carefully undo the nut under the carb bowl ( you may find it easier with the air cleaner back plate removed) and remove the bowl. If you are careful ( and lucky) the rubber O ring seal between the bowl and the body will remain in place. Flush the bowl out and refit it. Hopefully this will solve your problem. If the paper element is contaminated replace it with a genuine BS one. The primer button should have a moulded hole in the centre

 

hillsider Sun, 20/11/2016

Good to hear that you have resolved the problem, you are not the first person to be caught out by a filter that looks reasonably clean actually being blocked.

It seems to me that petrol will cause the paper element to swell blocking the pores and preventing the flow of air and no amount of drying off seems to cure it.

That's my theory anyway.