Hi i have a 16 year old Mounfield laser 3.7hp ransomes mower and just recently it kept cutting out! after repriming fuel it would carry on! but now it wont! it starts for 3 seconds then cuts out! i have cleaned the air filter and spark plug but yet it still wont carry on running! can a spark plug cause this problem? if you pump the black fuel thingy it carrys on running for a little longer but only seconds if any help?

Steve C, May 2009

Your problem is definitely carburation. These are not bad little carbs and the thing merely needs cleaning-out (these devices live in an aggressive environment and old fuel tends to varnish/gum them up over the Winter). Basically clean-out every orifice and jet that you encounter - especially the emulsion tube etc. Use an airline where you can - and if necessary a broken wooden toothpick/cocktail stick on the larger orifices. You may find a bead or two of water in the float chamber and/or the float sticking too. Get rid of the contaminated fuel in the float chamber, free the float as necessary, and carefully wire brush [or wet and dry paper] away any corrosion which has occurred within the float chamber bowl etc. GOOD LUCK!

The Mainecoon, June 2010