XUD not starting when hot - Compression Test

[Harky]

I'd be checking the timing next.....

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Or possibly an air leak that is only becoming apparent once the engine is hot and parts have expanded.
How does the grenade feel?

When you say check the timing, you mean check all locking pins etc? Or the fuel pump? I generally just set the pump to where it sounds the best.

Grenade seems ok. I tried pumping it till it was hard, then hot starting, same issue.

Tbh, I'd be driving away at the car, stopping for long periods of time or on a hill, wouldn't bother me, but I can't get through mot with a car that won't start hot!