Motorsports Village Racing Forum

Make Your Own Gas Primer System

written by: George McClain (gdmii)

If you use alcohol (methanol) as a racing fuel, you more than likely have experienced instances where the engine was very finicky to start. In fact, as outside air temperature drops, the more difficult the engine typically is to start. There are a couple of systems available on the open market that will inject gasoline into the intake manifold, thus, making starting the engine a much easier feat. These systems also allow the engine to make heat more readily, and, depending on the userís choice of fuel injection or carburetion, allow the vehicle to move about on gasoline until just prior to the burnout. As I run a carburetor, my need was only to prime the engine with gasoline to enhance starting. Instead of buying one of the commercial units, I decided to make my own by using a one gallon fuel tank, a small electric fuel pump, a fuel shutoff solenoid, a nitrous plate and jets, and enough #4 steel braided line to connect it all.

I started by mounting a one gallon tank next to my alky tank.

Fuel Tank

A one gallon tank will last for many starts. Next, get a small 1-3 p.s.i. electric fuel pump like the one below. These are very inexpensive and are usually found at your local automotive parts store.

Fuel Pump

Run a #4 steel braided line adjacent to the carburetor or wherever you are going to mount the fuel shutoff solenoid.

Fuel Solenoid

The solenoid is necessary to keep gasoline from being siphoned into the intake once the engine has started. Wire the solenoid to the fuel pump switch so that it is only open when the fuel pump is on. Next run a line from the fuel solenoid to the nitrous plate.

Nitrous Plate

I modified the nitrous plate by removing the nitrous rod and plugging the opening. I then ran the line to the fuel rod and inserted my jet. The jet I used is a #35 but I only use my system as a primer and donít idle my engine on this system. If you choose to use your system to idle on gas then you will have to play with jet size to fine tune it. Youíll have to experiment with the jetting depending on what your engine likes. For just starting, mine likes 3 seconds of gasoline along with 2 pumps of the throttle to throw a little alky in the mix. If you use a smaller jet, then you may need more time. Larger may need less. Just experiment with it to see what you need. In the picture above, I have the nitrous plate on top of a spacer that I have drilled and tapped for a lean out valve.

A BIG caution hereÖuse a spring loaded switch (momentary contact) for the primer fuel pumpÖone that must be held to the on position. There should be NO chance that this switch could be inadvertently left on which would fill the engine with gasoline. This is a simple installation but if you are not comfortable with it, then DONíT DO IT. And if you do install it, you do so at your own risk. Donít come crying to me if you blow your stuff up.

Before installing this system, I would have a fire in the carb on every cold start. Now I have easy starts and no more fires.


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