We got vapor lock in the old days because the fuel
tank was in the back of the car and the fuel pump
was on the engine. Also the fuel line sometimes ran
right next to the exhaust pipe. Vapor lock disappeared
when they started putting fuel pumps at the back of
the car or better yet in the fuel tank.

> Paul Lamar

Paul,
There was a bit of discussion on in tank pumps and non-return systems a while
back and I never really got the gist of how things worked until I got the
Manual for my new Suzuki 1800 cc sports cruiser.

The in tank pump takes fuel from the lowest point in the tank ( naturally)
and feeds it via high pressure fuel pump to a pressure regular ( in the tank
and part of the total unit) which returns fuel to the tank, when in excess
of the absolute fuel pressure of 300 kpa (43psi), which is fed directly to
the injectors.
The beauty of this system is the very short feed line to the engine,
therefore not much fuel to heat up.

I don't know how well it would work in an aircraft, perhaps with a small
forward tank - then the problem of overheating the small volume of fuel and
perhaps vapor lock may be an issue

Anyhow that's how it works, I thought it interesting having the regulator in
the tank as well.
George ( down under)



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