Motor starts to go up and down after half a hour

[JohnHendrikx]

So I have work to do and hope to find the issue
Many thanks for the information and advice!

John

 

[hlw49]

When it starts surging pull the fuel line from the tank loose and see if you are getting good fuel flow from the tank. I have seen fuel lines collapse when they get hot.

 

[zigyblu]

I would remove the fuel cap and see if it smoothens out and if it does your vent hole could be plugged. That should also help get a better flow of fuel to the inline filter.

 

[peteco]

Also check the coil, when get high temperature, probably fail. In old cars it´s the same.

 

[hlw49]

Try holding the governor arm still and see what it does. If the engine dies it is a fuel problem if it keeps running and smooths out it is a governor issue.