Primer Requirements

In order to start a cold engine equipped with a Throttle Body Injector, a combustible mixture of fuel and air must be admitted into the intake manifold using a primer. This can be a conventional plunger type primer in which the plunger pump is located in the cockpit, or an electric solenoid valve can be used that admits pressurized fuel into the priming ports when activated by a switch or button in the cockpit.

A excellent, inexpensive, electric solenoid valve is available from:

Acorn Products Corp.
P.O. Box 336, 49 Eagle Rock Ave.
East Hanover, NJ  07936
(973) 887-3662

The valve is P/N M-21A-3/64-1/8-12DC.

A schematic diagram of a primer system using the above electric selenoid valve is shown below.

An excellent article about fuel system design by Lyle Powell, may be accessed by clicking on Fuel Systems for Homebuilt Aircraft.