A sunny spring afternoon, a Jodel DR1050 with an O200, and mogas. Fuel tank top temperature was below 20C. Aircraft had been flown, and parked into a warm (for Inverness) wind for a short time.
The gascolator is behind the engine. Take-off is on the front tank, which is exposed to the sun. I used carb heat at the checks.
When I opened the throttle to take off, the revs rose to about 1600, then dropped, and the engine stopped. It restarted on the starter, and, after clearing the runway, ATC gave permission for me to shut down, exit and check the fuel. When I put the fuel tester to the gascolator, a froth spurted out. I restarted, returned to the hangar, and discussed the problem with our engineer. In the cool evening, I took off with no problem.