Author Topic: Lawnmower won't start...  (Read 868 times)

Lawnmower won't start...
« on: May 21, 2017, 12:10:45 pm »
Our 9yro petrol lawnmower (Briggs and Stratton series450 148cc model SV40S)  has failed for the first time.  Yesterday it started and then struggled to keep going, konked out.  I restarted it, then it died again after a couple of mins.  Today not starting at all.  I have de-oiled the sponge air filter, and oil (albeit old!) level is fine, as is fuel.

Any ideas, what can I try?
"an inordinate fondness for beetles"

Re: Lawnmower won't start...
« Reply #1 on: May 21, 2017, 12:14:11 pm »
If you take off the air cleaner, is the choke operating?  The cable may have slipped.  It's also worth checking the HT lead is securely on the plug.  You may also want to remove the plug to let it dry out, as the cylinder may be flooded with the attempts to start.

IME most problems with Briggs engines are traceable to the air cleaner - if the engine starts easily with the air cleaner removed, your filter may be invisibly clogged.
Never tell me the odds.

Re: Lawnmower won't start...
« Reply #2 on: May 21, 2017, 12:59:18 pm »
Nice one Roger, I think that's done the trick.  :thumbsup:   I took off air filter, still not starting. So I removed spark plug - cleaned off the coating of black soot and left it off for a while then reassembled (also pinching in the metal skirt of the spark lead).  The LM then started (without filter), and choke seems OK - I revved it a tad.  Fitted air filter and still seems good.  Just need to fix one of the wheels whose height adjustor keeps slipping out...
"an inordinate fondness for beetles"

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Lawnmower won't start...
« Reply #3 on: May 23, 2017, 01:18:13 pm »
Also worth regapping the spark plug every year or two, and replacing every 5 years or so.

Most problems in these engines seem to be avoided by keeping the filter clean and not tipping them forward - all the oil fouls the plug if you do, adn you get clouds of black smoke for about half an hour  :facepalm:
“Procrastination is the thief of time, collar him.” –Charles Dickens

Re: Lawnmower won't start...
« Reply #4 on: March 03, 2018, 04:47:16 pm »
Also worth regapping the spark plug every year or two, and replacing every 5 years or so.

Most problems in these engines seem to be avoided by keeping the filter clean and not tipping them forward - all the oil fouls the plug if you do, adn you get clouds of black smoke for about half an hour  :facepalm:
Tilting the mower forwards can have worse consequences like  creating a total hydraulic blockage with the oil trapped in the cylinder. The solution is to remove the plug, put something absorbant in front of the plughole to catch the oil and pull the cord a few times. Then put the plug back in and start. There will be a lot of oil and oily smoke from the exhaustive. Rechecking the oil level before starting is not a wasted exercice.