Fuel pump mounting/position

[gumpit]

Walbro Fuel Pump | Go Kart | Mini Bike
Does it matter how this is mounted? Does it have to stand up or can it lay flat? Can it be at an angle? Should it be below the tank or above? How much venting does the fuel cap need to compensate so there is no vacuum?

 

[CarPlayLB]

It does not matter how you mount the pump. I have had no issues with having a small vent, a standard cap is normally fine! I mount my pumps whatever way the hoses line up pretty! I do my best to mount below tank level as it will work better, but I have seen some mounted high

 

[jdogg]

I think you will be fine Randy as I believe they are a diaphram style pump as long as you have a good vacuum you should be fine mounted either way! This pump although different is mounted higher than the tank outlet and works great!!

 

[2SlickNick]

I have seen them mounted upside down too.
Don't forget a return line to your fuel tank. Too much pressure can cause the fuel to to reach the engine and flood it.
If you see my vid, I use the blue line to the pump. I red line goes from vacuum. I use the clear as te fuel return.
I put in a tee from the pump to the carb. One line from tee returns the pumped fuel back to tank and the other brings the pumped fuel to the carb. So in essence I am only getting half the pumped fuel - so there won't be too much pressure of fuel forced in carb.
Baja Doodle bug mini bike trike - YouTube

 

[jdogg]

I have seen them mounted upside down too.
Don't forget a return line to your fuel tank. Too much pressure can cause the fuel to to reach the engine and flood it.
If you see my vid, I use the blue line to the pump. I red line goes from vacuum. I use the clear as te fuel return.
I put in a tee from the pump to the carb. One line from tee returns the pumped fuel back to tank and the other brings the pumped fuel to the carb. So in essence I am only getting half the pumped fuel - so there won't be too much pressure of fuel forced in carb.
Baja Doodle bug mini bike trike - YouTube

Hey Nick I have heard that setup on a return is only necessary if going to a Mikuni style carb....too much pressure but a stock carb is fine with it?

 

[jdogg]

Also I have heard if you are using a Mikuni with a fuel pump you can regulate the fuel pressure to the carb from the pump with an inline fuel shut off valve but have yet to try it but I do have a setup that needs it.....

 

[2SlickNick]

Hey Nick I have heard that setup on a return is only necessary if going to a Mikuni style carb....too much pressure but a stock carb is fine with it?

I am using stock carb, but I guess I just wanted to be safe not sorry.

 

[Havasu Dave]

I used a pump with a Mikuni and had no problems with no return line being used, no flooding, and didn't bother with turning the fuel off.

Still, reducing pressure to take the load off the bowl valve o ring is a good thing.

Another thing I heard is that if distance from tank to carb to pump is an issue, it's better to run the pressure line short, and the fuel line long.