Fuel Pump Setup

When it comes to serious OHV 4 cycle engines, you need to ditch your gravity feed setup and install a fuel pump. Our Mikuni fuel pump is simple, easy to install and operates off the the pulse created by the engine. There are many different locations to mount the fuel pump. One thing you want to keep in mind is the fuel pump should be as close as possible to the source of the pulse which runs the pump.

The fuel pump pictured has been mounted on the fan shroud. Once the pump is mounted you have three lines to hook up.

The fuel line on the right is coming from the gas tank and going into the inlet on the fuel pump.

The fuel line on the left is coming out of the outlet and going into the carburetor.

The fuel line in the center is the pulse line that runs the fuel pump. We drilled and tapped a hole in the engine side cover and installed a pulse fitting. A pulse fitting is nothing more than a brass fitting you can find in your home improvement store's plumbing department. In the picture above the engines side cover was used as the source of the pulse to run the fuel pump.

When it comes to the pulse line you have several options. The best option would be to use our carburetor adaptor with the pulse fitting (12372).  This adapter is used with the 22mm Mikuni.  This provides a clean pulse source where you do not have to worry about oil getting in the line.  

If you plan to use the stock carburetor you have a few other options for the pulse source. The govenor hole once the govenor has been removed is a common place to attach a pulse fitting for the fuel pump. The problem here is you will occasionally get oil in the pulse line just like using the side cover method. The oil will limit the fuel pumps performance and require you to open up the fuel pump to clean the oil out.

The best location for the pulse line when using a stock carburetor would be from using one or our carb insulators with vacuum takeoff (20650).  This is also a clean location where getting oil in the line is not a concern.  

The next option we used for the pulse line was drilling and tapping the engines side cover. This picture shows the location of the pulse fitting in the side cover. This pocket area provides some protection from oil getting into the pulse line.
The last option we'll share for getting a pulse to your fuel pump is by installing a pulse fitting into the valve cover. This is the most recent method we have used and to date we have not had a problem with oil getting into the pulse line. When you are using the stock carburetor and a carburetor adaptor is not an option, we think this method is the next best option.
You need to drill a hole in the top of your valve cover for the pulse fitting. You will notice there is a baffle with a one way valve inside the valve cover. You want to be sure to clear the baffle.
Here we have marked the location where we are going to drill the hole. Then we used a center punch on our mark.
We used a 25/64" drill bit to drill our hole. We cleared the baffle, however it's a tight fit.
The pulse fitting has an NPT thread. This means the threads are tapered. So the further you screw the fitting in the tighter it's going to get. We screwed this fitting until it was pretty tight creating a nice seal.
Here is the valve cover installed with the pulse line.