Fuel system woes

Hi Mark,

I had the same problems ages ago. Naturally I cannot tell for sure that the source of probs in your case are identical. However, when shutting the engine down there will be a significant increase of temperature underneath the cowling. This will heat up fuel in the fuel hose and may explain the increase in pressure you report, too. Depending on the seasonal type of fuel you currently run the fuel my start to boil and vaporize at pretty low temps, temps you easily reach after shut down. That makes it very difficult to restart the engine for a while.

a) heading the nose into the wind and have natural airflow cool everything down - this is a rather low tech solution

b) install heat protection sleeves on your fuel lines underneath the cowling which slows down the heating up significantly. You may already get away with that

c) use b) and install an additional electric pump. That helps to increase pressure on the fuel in the fuel lines underneath the hood (a bit). Some extra pressure helps to increase the boiling temp to some extend (looking at the water circuit the 1,2bar cap instead of a 1,0bar cap counts for approx. 20C).

Long story cut short, c) made my fuel temp restart probs go away for good.

In my plane there is an electric fuel pump before the engine driven pump. The fuel system has a return line with a small orifice back to the tank. Before starting, especially when the engine and ambient temperature is high the procedure is run the electric pump for at least one minute. This helps push the hot fuel out of the lines. The vapor lock Peter Kl mentioned is very real with the symptoms you are experiencing. Very unlikely that you are experiencing a flooded engine. 

😀