Fuel Injection: Epilogue...
It is now several years since I made the switch to fuel injection. It was certainly worth the effort and has dramatically improved driveability and economy.
However, last summer (2010) in 43 degree heat I did experience fuel system issues, with the pump cutting out a couple of times when away at the Le Mans Classic.
My conclusion has been that in the very hot ambient temperatures the fuel in the return lines got so hot it started to vapourise and prevented fresh fuel gravity feeding from the tank above, which in turn caused the the pump to overheat.
In ordinary temperatures and ordinary running enough fuel is consumed by the engine for fresh fuel feeding the accumulator from the tank to keep things sufficiently cool. But not in the hottest weather i've ever experienced...
So out goes the gravity fed fuel accumulator, to be replaced by a swirl pot fed by a low-pressure pump. And in comes a return line back to the tank so that the low-pressure pump is continually refreshing the fuel in the swirl pot by that in the tank.
That way, the whole volume of the tank would need to heat up for me to experience a repeat of the problem.
As a further measure I'll also add a heat insulating gasket between the manifold and throttle bodies reducing the thermal transfer into the fuel lines in the first place.
So, the fuel system has changed from this:
I'll report back on whether these changes have the desired effect later in the year (assuming we get a hot enough summer!).