edwardc Posted August 3, 2015 Share Posted August 3, 2015 I have a PAP 1250 with the M25Y Black Devil engine and I have just got it out to start it up (a bit late in the year but I have other hobbies!) and it will start after priming but won't run! I assume that there is no petrol being 'sucked up' to the carburettor, can somebody explain how this works and what I should be doing please? Thanks for any help Eddie Quote Link to comment Share on other sites More sharing options...
Guest Posted August 4, 2015 Share Posted August 4, 2015 You will most likely need to replace the rubber diaphragm 'pump' in the top of the carb as they go brittle and crack when not used for long periods. It will come as part of a carb service kit Good luck SW Quote Link to comment Share on other sites More sharing options...
edwardc Posted August 4, 2015 Author Share Posted August 4, 2015 Hi Simon Thanks for coming back to me. I have ordered a service kit but the old diaphragms look okay so not sure it will make a difference! I am not clear how the system works, can someone explain how it works? It appear that the primer pumps petrol into the head through the decompressor and into the crankcase via the carburettor flange. What pumps the fuel up (or sucks) after that? Regards Eddie Quote Link to comment Share on other sites More sharing options...
Guest Posted August 4, 2015 Share Posted August 4, 2015 The pump is actually that flimsy little diaphragm mate It goes up and down and sucks the fuel. Keeping it simple. SW Quote Link to comment Share on other sites More sharing options...
spigot Posted August 5, 2015 Share Posted August 5, 2015 The other side of the pump action is the flimsy D shape plastic or rubber valve sheets. you will have both in the repair kit, replace like for like. They become brittle and fall off occasionally. Quote Link to comment Share on other sites More sharing options...
bholleran Posted August 6, 2015 Share Posted August 6, 2015 On the side that the fuel enters the carb, there is a tiny gauze filter that often gets blocked, and would exhibit the symptoms you described Quote Link to comment Share on other sites More sharing options...
edwardc Posted August 7, 2015 Author Share Posted August 7, 2015 Thanks for the advice guys, the carb kit turned up yesterday so I will have a go at the weekend. Cheers Eddie Quote Link to comment Share on other sites More sharing options...
Guest Posted August 7, 2015 Share Posted August 7, 2015 Pop it down if you have any dramas chap SW Sent from my iPhone using PMC Forum mobile app Quote Link to comment Share on other sites More sharing options...
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