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Collection, Preservation and Display of Old Lawn Mowers

Help starting a mower please

May I have the collective expertise of our members to help solve a mower starting problem.

The mower in question was drained of fuel before being put away last year, the motor was run until the carb ran out of fuel.

This year I hoped that filling it up with fresh fuel it would start, sadly it doesn't.

I got a spark at the plug and I've convinced myself that it's a fuel problem of some sort. If I remove the spark plug and give a squirt of carb cleaner direct into the engine it will start first pull and run for perhaps a few seconds until the carb cleaner runs out.

I've removed the tank and given it a good blast of compressed air and cleaned through the fuel line from the tank to the carb. Still doesn't want to start. Stripped the carb down and gave it a clean with carb cleaner and compressed air but still not starting.

During the strip down I noticed that there was a "solid" piece of something in the fuel line and it has a bulge in the fuel line. Can anyone tell me what this is/for? On the bottom of the carb is an adjustment but I'm not sure what it's for and where to best set it to get the mower started.

Any advice is welcomed as I've worn out my wrist trying to start the engine and failed :-(



wristpin Wed, 13/04/2022

As ever a couple of decent images are worth more than lines of text!

Reads as though Fuel is not reaching the carb , or if it is, there’s a blocked jet.

Take care with compressed air , it may dislodge the float needle seat, never to be seen again.

For now, disconnect the fuel pipe from the carb, hold it over a suitable clean receptacle, turn on the fuel, or add fuel to the tank and check that flow is maintained for at least 30 seconds.  

wristpin Thu, 14/04/2022

Only guessing that the bulge is sintered porous   filter of some sort which may be blocked by stale fuel. Have you tried the flow test that I suggested ?

AlanY Fri, 15/04/2022

Thanks for your comments, I plan do have a look over the weekend and will get back to you with the results



AlanY Sat, 16/04/2022

Thanks for the help.


You are right, it was a sintered bronze filter, which i have now removed. I don't think it was inhibiting the flow but I took it out just in case. The flow test you suggested all checked out OK.

Any idea on what to set the adjustment screw that is underneath the carb?

Once I have get that somewhere near right, it might start. If not I think I'm back to looking at the carb again.

Any words of wisdom are appreciated.

wristpin Sat, 16/04/2022

Screw it in fully ( gently ) then open it one and a half to two turns and see what happens. If it starts but fluffs and puffs, screw it in until it runs smoothly. 

AlanY Fri, 22/04/2022

Thanks everyone for your advice and comments. The mower is now up and running. The problem being traced to a sticky float valve staying closed.:-)