by Markku
(81700 Lieksa, Finland)
The engine runs normally at low revs. When the revs rise above about 4500, the engine starts to jerk. It feels as if the ignition is cut off for less than a second, often in periods of a few seconds all the time. Or can the fuel system interrupt the fuel supply? No fault light appears. If you reduce the revolutions to about four thousand, the engine works normally. Where could I look for a fault?