Hello,

I would like to ask for your help before I order a new petrol pump. Maybe I missed something during my investigation.

The problem with my Sherco St 300 from end of 2013 is that the carburetor does not get fuel or gets too little.

I first checked the vent of the fuel tank - one-sided valve ok,  fuel hose - ok,  fuel tap - ok.  Just to be sure I started the engine with the unscrewed fuel tank to be sure the reason was not to vent the fuel tank

I disassembled the fuel pump -  cleaned - I have not seen any signs of wear or damage.

I started the engine. After a while the fuel stopped flowin. I disconnected the fuel lines and fed the fuel directly to the carburetor using a syring. From disconnected fuel supply line from the pump to carburetor fuel does not flow. During engine operation in a normal situation petrol pump should pump fuel  ?

Do you have any ideas what else should I check?

 

Edited June 19, 20179 yr by gleiwitz

2 minutes ago, oni nou said:

Pump works by vacuum  created by piston downstroke  so check the vacuum pipe that goes from the carb intake rubber area to the pump itself.....if it has a cut/hole in it or is trapped/pinched somewhere then you have no vacuum and therefore no pumping will take place.

Thank you very much for the reply!

I checked the hose only visually. I did not dismantle it.  I checked its position so nowhere is trapped / pinched. I will check tomorrow whether there are any holes or cracks.

Apart from the vacuum pipe, something may be the reason for not creating a pump-induced depression? 

3 minutes ago, oni nou said:

Yes a hole or non sealing of the diaphragm in the pump itself.

 Thank you very much for your help.

I will check it and if vacuum pipe will be ok  then I will order a new pump because I am slowly losing patience

A friend had the same problem, I think it was a kink in the pipe when reassembling the bike.

 

Or dirt blocage into fuel tank tap. 

Thanks a lot guys for all tips. 

I will check the vacuum pipe carefully today. Just to be sure I will put on a new pipe and we will see  

 

breather pipe from carb too long gets clogged with mud, sherco known for it,

 

Problem solved

The cause of the problem was vacuum pipe. It was not visible but when  I disassembled the vacuum pipe I noticed that hose/pipe clip was badly mounted at the very end which caused the hose to deform and consequently leak / catch the air.

 I mounted a new vacuum pipe on the lef side of carburetor where I my opinion is more space and pipe will not bends

 

Thanks a lot for your help.

Today I was practice and unfortunately the pump stopped working again I got upset and ordered a new pompe. I hope this will resolve the problem definitively.

Heheh It will be funny when I will instal new pump and it turns out that it still does not work hehehe