Andrew Ferriby Posted May 31, 2009 Share Posted May 31, 2009 Hiya People. I have just fitted my new Zenoah 20cc engine to my Piper Cub, following all instructions. The problem is........ When I turn the prop.... its not pulling the fuel through the fuel lines! There are no blockages at all in the pipes..... I cant even blow air into the carb with the throttle open! I have took the throttle to bits, and there is a mesh inside the throttle..... Once this is removed the engine will pull the fuel thorugh the pipes!!!!!! But its obvious that the mesh is there for a reason!!!! Do any of you have or had the same problem? Thanks, (PS - Its from Ajay Models) Andy Ferriby Quote Link to comment Share on other sites More sharing options...
Stephen Grigg Posted May 31, 2009 Share Posted May 31, 2009 I assume its a filter Andy and wonder if it can be blown through 1 way but not the other like a valve,otherwise maybe its a filter thats blocked possibly Quote Link to comment Share on other sites More sharing options...
Aero120 Posted June 16, 2009 Share Posted June 16, 2009 Andy, Mine is the same for the first start of the day. My solution is to put my thumb over the air intake and turn the prop until I feel petrol on my thumb, then start it without the choke. For the rest of the day I use the choke as per the instructions. On the Toni Clark site there is a guide to an installation and they soldered over the holes in the choke butterfly so I think the engine is a bit weak at sucking fuel until its running Quote Link to comment Share on other sites More sharing options...
NealeG Posted April 23, 2011 Share Posted April 23, 2011 Hi Guy's I have a new Zenoah 20cc (ei) and the same thing happens takes ages and plenty of energy to turn her over by hand. Tried the choke method as discribed in the instruction and covering the intake to draw the fuel through but it's hard work to get her going whether she's cold or just after a run when she's still warm. I have had about 5ltrs of fuel through her so she is run in for sure. I have now resorted to using a starter motor same as used on the glo's and she fires up everytime, am I doing any harm ordamage using a starter motor with electronic ignition? Quote Link to comment Share on other sites More sharing options...
Snorbitz Posted April 23, 2011 Share Posted April 23, 2011 I'd never start my 26cc without a leccy starter.....even with the choke closed i'd be there all bloomin day!!.. Doesn't seem to harm anything so far as i can see. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 28, 2011 Share Posted April 28, 2011 Not a petrol man myself so limited knowledge but as I understand it the Walbro carbs have a pump to bring fuel up to carb itself. This is a diaphragm pump which operates via the pressure pulses from the crankcase. Given that petrol motors use very little fuel & that this pump operates at several thousand pumps per minute (ie crank speed) then it follows that each pump "stroke"will move very little petrol hence bringing it all the way from tank to carb will take some number of turns of the engine.....!! Using the suction from the motor itself as we do with glow motors makes a lot of sense!!! Might also be worth ceching that the tube between the crankcase & carb is in good condition... Quote Link to comment Share on other sites More sharing options...
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