I have a Champion Lawnmower with a Honda 5.5 engine. It starts first pull but will only run for about 40 to 45 seconds before it cuts out. It will start again afterwards (it takes a couple of pulls though) but again will only run for 40 to 45 seconds. I have drained the fuel and refilled with new but still it persists. any ideas?

Andy Roberts, February 2008

Yep... have just replaced the coil (£40 ish) and it now runs perfectly (...still a bit mystified that a dodgy coil should cause the mower to behave in that way though).

Spike Mooner, March 2008

Hello Andy. My father-in-law has exactly the same mower, with exactly the same problem. We have checked the fuel supply, cleaned and checked the carb float chamber and jets etc. All absolutely perfect, but still the problem persists. I am now wondering if the coil assembly might be breaking-down. Have you had any luck resolving the problem yet?

Spike Mooner, March 2008

I would look at the carburettor diaphragm as this is the normal cause of starting issues plus check to see if it has a blocked air filter, when the air filter gets resistance the engine sucks on the diaphragm damaging it. If it’s a model with out a diaphragm carburettor check the jets are clean. You could try placing a cloth over the filler on the tank, blowing into the fuel tank to pressurise the system this can force small bits like fuel varnish etc to pass through the carburettor internals but do not use compressed air as you will empty the tank all over yourself! And do it in a well ventilated area or outside. Do you use a fuel stabiliser in the petrol as petrol starts to go stale after a short time …like 30 days!!

cache1, February 2008

Sounds like it could be a blocked fuel filter. Clean the fuel system through.

Christopher Mark Kingsbury, February 2008

More than likely there is a restriction on the fuel supply here - pull off the pipe to the carburettor to see if fuel flows freely. If it does then there is no restriction in the tap or filter (if fitted). If alls well here, you need to remove the carburettor float bowl and remove the float complete with needle valve and blow the fuel passage clear - take the carb. off for this though, its much easier. It could be worth trying a new spark plug first though, just to ascertain its not breaking down due to heat.

John, February 2008