Running problem on 40-plus

[Geertje]

Hello All,

I have a running problem on a 40+ that is puzzling me.

Sometimes after a period of normal operation the engine begins to sound as if it is struggling and revs drop significantly - sometimes stabilising at a lower speed, sometimes continuing to head downwards as if the motor is to stop.

What I have found is that comnpletely obstructing the air inlet with the tip of a finger for a fraction of a second and then releasing it causes - after the momentary downwards blip - the revs to immediately rise again to the normal level and the engine to continue running at full power.

Any thoughts about what's going on?

[Vic]

I think I would start by cleaning the carb, the jet and the foat chamber, and the fuel tank.

If you are filling it from a can check that for contamination, esp water.

[Katomi]

One more thing to look at is how do you mix your petrol and oil. I was out yesterday and someone had the same problem.. He was putting oil in the tank then adding petrol. the oil was sitting in the fuel pipe .
Hope this of some help
Stephen

[CatiGull]

Classic water contaminated fuel running behaviour...