Chainsaw doesn't run for very long, need help?!?

Question

I have a JCB Chainsaw. I have to press the yellow fuel bubble a couple of times and then give it a pull about 10 times before it starts and only on half revs. Then I rev it up and it goes for about 15 sec then it splutters and struggles and grinds to a halt. Then you repeat the whole process over again and exactly the same happens? Any Ideas??? BTW - I have checked the spark plug

Answer 1

old fuel can give same problem,if the fuel has been in there for months , renew it. takes a couple of tyres to pull the fresh fuel throe the carb, as has been mentioned - check the yellow bubble primer first

Answer 2

Sounds like a fuel blockage to me.

Answer 3

You may have to clean you fuel filter

Answer 4

You may not be priming it enough - all of the machines I have with bubble primers have X8 marked beside the bubble.

Answer 5

Inspect the plastic surface of your primer bubble pump I suspect it has a hair line crack in it and it draws in air after you start the saw.

They can be replaced by removing the four small screws and installing a new one.

Answer 6

try cleaning/replacing air filer and fuel filter. If it has been sat for a long peiod of time drain the fuel and replace with fresh fuel with correct oil mixture. Hope this helps

Answer 7

You may have some dirt in the fuel system - probably a piece of sawdust - it sounds as though it is being carried into the carb and blocking it.  Sorry to say, but I have not had good reports of JCB power tools.  They seem to be only for very light use.

Answer 8

Most chainsaws have a fuel filter in the fuel tank.  It is on the end of the supply hose.  Fish it out with a piece of wire and change it if it's dirty.  Most likely cause is the carburetor.  You can rebuild it very easily.  You can get a rebuild kit from most any small engine repair shop.  You will need the brand and model numbers off the carb to get the right kit.