Hello!

I have a mysterious problem with my engine. It runs perfectly for about 15-20 min and shuts down after that. It wont start after that, before cooling down.

Tank is up high, and fuel seems to be running well after disconnecting lines. 

 I've replaced all fuel line seals and made sure that there are no air leaks.

I've also replaced fuel pump and injector unit with new ones.

What am I missing here? Blown head gasket? Cracked cylinder or head? Are these common?

Fuel injection timing?

My headache isn't going away before I have my Lister running again!

So please, any help is wellcome!

-JP