25% Increase In Gas Mileage With Fuel Shut Off

25% Increase In Gas Mileage With Fuel Shut Off

On the older carb type engines, Energy Conserver can be used, as in the manual. Method puts vacuum on upper level of float bowl housing with manual adj valve pre set, so as no gas comes out the carb. Can be done with manually operated push switch on column, to operate 12v solenoid valve . 25% increase in MPG. Done by Eagle Research people many years back. You shut off the gas when coasting long distance deceleration to stop light/sign. Everything still works because crankshaft is revolving. (thumb over straw filled with water does not leak out.) The modern injector engines can use a 12v DCrelay to shut off the ground wires during deceleration period. Release just before stopping. See repair manual for color coded wires.

Sounds like a study from the 1940s I read.  Cars have changed a lot since then, and I admit, I love my power steering and power breaks which requires the engine running.  (As I found out going crazy speeds on the usa I5 and my engine quit)

When I was in school, we went to the city dump because they had the most accurate scales in town that could weigh a car.  After a day of testing,  we concluded that a 1990 model car costs as much fuel to start as 3 to 5 min of running on idle.  So it wastes fuel to turn it off for short stops like traffic lights or down hill, but very good idea to turn it off for long waits.

It's a very different engine than they had during the last war.

And very different from modern cars.  I drove in a new one the other day, and they have redesigned it to shut off at traffic lights and the like.  But it looses about 4 seconds reaction time which is a lot.  (Maybe 2 seconds when one gets used to it)

I love that my school taught me to test things for myself and see if what we knew in the past, still applies today.  There is so much to learn.

Over run cut off was first played with by Jaguar on injection systems 50 years ago.

After some teething issues, it's become standard on fuel injection systems.


For modified equipment, where are you placing the shut off solenoid?
Diesels use the fuel as a lubricant, you might start seizing fuel pumps if you let the pump run too much with no fuel.