Thanks Bruce, and well done. I saw it was a non-genuine cap and didn't think any further. Lucky someone around here is on the ball, since I obviously wasn't. I had been having trouble working out why the pump diaphragm would work for 5 seconds then stop, but would recover in a short time. I'm hopeful there won't be any damage to the diaphragm, since it didn't run for long each time it started. Mower man will find out when he starts it with the fuel cap removed: if it runs properly, all he needs is a fuel cap from some junked Briggs engine.
