Small Engine Repair: Checking a Vacuum Fuel Pump / Fuel System on a Kohler V-Twin Engine
**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.* Checking the fuel system, and vacuum fuel pump on a V-twin 25HP Kohler engine involves checking the fuel lines that attach to the pump, and checking fuel flow. The first step is to check to make sure fuel can flow from the gas tank to the fuel pump. To do this, disconnect the fuel line from the vacuum inlet fitting on the vacuum pump. Take the fuel line and lower it to a point that is below the fuel tank and see if gravity will cause fuel to flow from the tank through the line. If fuel flows, than the line is clear. If fuel will not flow, than check the fuel filter to see if it is restricted. Also check the fuel tank shut off valve if the tank is equipped with one. The valve may be in the off position, or dirty and restricted. Check the fuel tank cap to see if the vent on the fuel tank cap is plugged. If the fuel tank cap vent is plugged than fuel will not flow out of the fuel tank. Next, check the pulse line on the vacuum pump. Make sure it is connected correctly to both the vacuum pump and the engine crankcase. Also, make sure the engine is not overfilled with oil and the pulse line is not filled with oil. If the engine oil is overfilled with oil, than oil can make its way into the pulse line and block the pressure necessary to operate the fuel pump. The next thing to check is the fuel line from the …
Video Rating: 4 / 5
where is the tube connected to the block providing the vacuum?
Sounds like you need a good old tune-up.
Thanks for commenting.
After replacing my fuel pump, I had white smoke while running and backfiring when turning the mower off. I only ran it for about 10 minutes before the engine died and wouldn’t start at all. I found the carburetor full of oil and the head gasket was blown. Cleaned and replaced both but it still wouldn’t start. From your video, I see that I had my vac and fuel input lines reversed, so I was sucking oil from the crank. Anyway, thank you for showing me my own stupidity.
I have engine like that and it is running rich and it wont start and when it dose run it runs bad. I need help.
THANKS…
Thanks for watching!
Excellent video. Thanks for taking the time to make it.
Thanks for watching!
Thanks for the info, it seems Polaris is guarding this test method so only the shops can perform it.
Thanks!
very well done. Thank you. I will be ordering a new fuel pump.
Thanks for watching!
Thanks for the information. My father has a Kohler engine that is having problems but, I wasn’t sure how to verify the operation of the fuel pump. I wasn’t sure if the pressure was high enough. From what you said, it appears that the pressure isn’t as important as the fact that an ample amount of fuel is flowing. I’ll now focus on the carb float etc.
Thanks again.
Thank you, and thanks for watching
Go to Kohlers website and download the manual for your engine. Find the trouble shooting flow chart in the manual, and I think that will give you some ideas about what might be wrong.
@smallengineshop i have kohler command pro 20 v-twin and when ever i engage the PTO for the blades at full throttle it chokes down any ideas? carb was cleaned spotless fuel pump works new plugs coils cleaned, these are the things ive done
Thank You!
Thanks for posting this! Good work.
You can find them as Sears, Harbor Freight, Lowes…etc. Thanks for watching!
Where did you find those pliers?
Excellent video, I was looking for information on vacuum pumps, thanks for putting this up.
Thank You!
love watching all your video’s…they are quite informative. Keep up the great work!
Your welcome! Glad it was helpful.
Thanks for the video. The information was extremely helpful with the repair of my pressure sprayer. Different engine make, but nearly identical fuel delivery system. Nice job.