I would offer this advice..
The fuel may be boiling in other places, other than the injector lines..
My airplane was converted from carbureted to fuel injected some time ago. A dukes boost pump was added on the engine side of the firewall.
After shutdown and it heat soaked for a bit, a bubble would form in the boost pump. When the pump was turned on, it would essentially run dry and not move any fuel. (Verified by fuel flow and pressure, plus you could hear it zing up to rpm) So, the quick fix was to crank the engine and the mechanical pump would pull the bubble past the boost pump, then leading to a normal hot start. But, once
started fuel pressure would be very erratic and often low, combined with engine stumble. It took a few minutes of running to clear the system of the air and normal fuel pressure would return. 25psi+
This boost pump was in an "airbox" with cooling air provided by a blast tube off the rear baffle. In flight that theory worked, but not when parked. I think the box itself was the main cause of the heat soak problem, along with the orientation of the pump/lines.
Solution:
Moved pump/lines to a point where a bubble would migrate uphill through the boost pump to the mechanical pump. (Then you could always push the bubble with the electrc pump, if you got one) Also removed boost pump "airbox" and only use a cool air blast tube for cooling. Let the heat
escape in to the cowl when parked. Haven't tested this yet, as still finished up V2.0 firewall forward stuff.. :)
Moral of the story: notice location of all fuel system parts and relative heat sources, moving and not moving.
Tom McNerney