Small Engine Repair: Checking Fuel Pump Diaphragm & Inlet Needle on a Diaphragm Carburetor

**Always follow the instructions in your repair manual when doing repair or maintenance work on Outdoor Power Equipment. Manuals can be found at the manufacturers website.**

In this video I show how to check the fuel pump diaphragm and inlet needle for leaks on a diaphragm carburetor. A diaphragm carburetor is used on hand held power equipment, and are popular because they will work in any position. All chainsaws, trimmers and blowers that I have seen use a diaphragm carburetor. To check the fuel pump and inlet needle, pressurize the carburetor to 10 psi through the fuel inlet. The carburetor should hold the pressure fairly steady, and if it doesn't than there is a leak around the fuel pump diaphragm or inlet needle. You can pin point the leak by dunking the carburetor in water while it is pressurized. If the leak is around the fuel pump diaphragm, than either the fuel pump diaphragm, fuel pump diaphragm cover or the body of the carburetor is at fault. If the leak is coming out of the venturi, than the inlet needle or seat is faulty.

Tools used:
- 3/8" wrench to remove carburetor
- Mityvac to pressurize the carburetor
- Needle Nose plyers

Specifications:
- Carburetor should be pressurized to 10psi through the fuel inlet. Never exceed 10psi. Its important to run fuel through the carburetor before testing. A wet carburetor will hold the pressure better than a dry one.

Category:

Autos & Vehicles

Tags:

• howto
• tutorial
• instructional
• mechanic
• engine
• stroke
• outdoor
• power
• equipment
• chainsaw
• trimmer
• blower
• weed
• eater

[ScottAtwater1]

thanks for the info

[smallengineshop]

@ScottAtwater1 Your Welcome! Thanks for watching!

[backwoodsctryboy]

can u do the same thing by pressuring the hose connected to the fuel filter and not remove the carb?

[smallengineshop]

@backwoodsctryboy You have to remove the carb to know where the leak is coming from. Thank you for Watching!

[dooman42]

how do make it a a pump i got one and it just sucks in

[smallengineshop]

@dooman42 There is a switch on the side of the tool that you turn 90 degrees to switch from a pressure pump to a vacuum pump or viseversa. Thank you for watching.

[ScottAtwater1]

You you know what the best oil mixture for the old chainsaws? that oil mixture has been

outdated that use 30 SAE, 40 SAE

[RoncoShop]

@dooman42 YOU CARBURATOR PROBABLY NEEDS TO BE CLEANED OR REBUILT CHECK OUT RONCO CENTER .COM FOR PARTS JUST SEARCH YOUR MODEL

[RoncoShop]

@backwoodsctryboy IF YOU NEED PARTS CHECK RONCO CENTER . COM

[smallengineshop]

@dooman42 There is a switch on the side of the tool that you turn 90 degrees to switch from a pressure pump to a vacuum pump or vise versa. Thank you for watching.