Testing the vacuum Pulse Fuel pump

[chuck$ter]

My V-Twin started running really rich and and smoking. I started to test the fuel pump since there was fuel in the Vacuum Pulse line. I pulled unit and cleaned it up. If I blow from the fuel inlet side I can feel air flow all the way through. If I blow from the outlet side to the inlet side, it is sealed.. Makes sense so far.. Here is where the issue is.. If I blow on the fuel inlet side and block the fuel outlet side, It leaks air out the vacuum port. Conversely, If I block the fuel outlet and suck on the Vacuum port, It leaks through the fuel inlet port.

I'm no expert but that tells me that the vacuum line is sucking gas through the diaphragm since it wont stay sealed. Thus I need to replace the Fuel pump? Correct?

 

[ILENGINE]

That is what I am thinking also. Punctured diaphragm

 

[chuck$ter]

I couldnt stand the suspense, I cracked it open and sure enough, there was a small hole in the diphragm.. I went to a local Mower shop and got another.. Running great again.. By the way, that pinhole causes raw fuel to be sucked straight into the manifold of the cylinder. In my case it was a Vtwin so it flooded the left cylinder. The mower stayed running because the other cylinder was running fine because it has its own intake manifold..

 

[Born2Mow]

Great diagnosis and good find !!

I'd highly suggest removing the dip stick to 1) smell the oil, and 2) look at the oil level. Gasoline could have easily diluted your engine oil. Does the engine oil smell of fuel, OR did the oil level rise any ? Both of these are indicators that gasoline is in the engine oil... and oil and filter should be changed immediately.