Humour_me Posted February 14, 2012 Report Share Posted February 14, 2012 Hi guys I'm in need of some help trying to fix my rotavator again. This was the state it was in last time HEREI managed to fix all the wiring then it all went wrong. Its a bit of a long story so bear with me. First time after trying to change the wiring it wouldn’t start some one suggested to me that on the carb there was a screw on the bowl and to undo this and drain it. Sure enough I undid the bolt and a thick sludge come out then ran clear. I assume the sludge was from when changing the wiring and had it in all orientations. First pull after this it started. Put it back on the rotavator started it, it ran for a minute then backfired and stopped. It refused to start again and would backfire every 1o pulls or so. I looked on the internet as to what would cause this and it seemed it could be a dirty carb and with the sludge before I thought this was it. I took the carb off and cleaned it all out didn’t seem to bad and put it all back together. Started first pull. Once again I thought I had solved the problem. Put it back on the rotavator and it did pretty much the same thing stalled after a few minutes, tried to start it again and BANG! Again every 10 pulls or so it would back fire. I took the carb off once more and in the inlet bit there was what looked liked water. Searched google found out water can cause the issues I was having. Cleaned it all out again drained the tank and filled with some fuel (some left up the field from last year). Put it all back together and you guessed it ran for about 5 minutes and stalled, wouldn't start again and would back fire trying. By now was getting a bit fed up so once again took the carb apart (I'm an expert now) and again was some water. I realised I'd been a bit silly using the fuel container that it was last filled from. Cleaned it all out drained the tank and went to get some new fuel. Put it all back together and tried to start it. started on the first pull. I thought I would just leave it idling for a while to see if it would stay running. It ran fine for a good 10 minutes so started rotavating feel quite happy that I’d fixed it. After 5 minutes or so it stopped and again wouldn't start. Took the carb apart no apparent water all very clean. I've just about ran out of motivation now. If any one has any ideas I would love to hear them. I'm not that well versed with engines so I may well have over looked something. If not ebay it is! Adam Quote Link to comment Share on other sites More sharing options...
lister1 Posted February 14, 2012 Report Share Posted February 14, 2012 What engine have ya got? If its Honda has it got an oil level cut out? Quote Link to comment Share on other sites More sharing options...
lister1 Posted February 14, 2012 Report Share Posted February 14, 2012 Could be the carb needs a propped clean out. I used to repair horticultural machines for a living and dirty carbs was a big problem. We used to take the carb apart and put them in a ultrasonic cleaning tank. Quote Link to comment Share on other sites More sharing options...
Humour_me Posted February 14, 2012 Author Report Share Posted February 14, 2012 Sorry should have said its a Honda GX200 clone. It's not the oil level sensor unfortunately as that just cuts the spark, so I’m guessing it wouldn't run at all and wouldn’t backfire? Quote Link to comment Share on other sites More sharing options...
lister1 Posted February 14, 2012 Report Share Posted February 14, 2012 Checked valve gaps? Can't remember what they should be. Could simply be muck in the carb. Quote Link to comment Share on other sites More sharing options...
Ratman2 Posted February 14, 2012 Report Share Posted February 14, 2012 Have you tried a new plug??? Quote Link to comment Share on other sites More sharing options...
Humour_me Posted February 14, 2012 Author Report Share Posted February 14, 2012 Just looked at youtube on how to check the valve gaps doesnt look to hard. If they were wrong what happens? Will try and check them tomorrow. I havn't tried a new plug but when I changed the wiring I checked it worked then (to check wiring was correct)and it looked ok and spark seemed strong. May get another one and try it. Lister1 I thought the same as you muck in the carb but I've cleaned it so many times. Just seems odd that it will run after every cleaning for a while. Quote Link to comment Share on other sites More sharing options...
timps Posted February 14, 2012 Report Share Posted February 14, 2012 (edited) Have you tried a new plug??? Definitely try a new plug, I would bet good money on it. I had a similar problem with with a Honda generator,oil cut out ok, carb clean, strong spark...... The thing is when the plug gets hot it fails, so it starts runs for a bit then backfires and stalls and will not restart till the plug cools down. I fitted a new plug fitted everything fine. Edited February 14, 2012 by timps Quote Link to comment Share on other sites More sharing options...
Humour_me Posted February 14, 2012 Author Report Share Posted February 14, 2012 You know what timps the first time it did all this I left it for a bit to cool down (thought it just got hot) and when I come back it worked again. Will be trying a new plug tomorrow. Thanks guys Quote Link to comment Share on other sites More sharing options...
lister1 Posted February 14, 2012 Report Share Posted February 14, 2012 If a valve is wrong then a valve may stay open and they pop and bang but don't run. You could have muck in the fuel tank. So every you clean the carb it just gets filled with muck when you fill the carb again. Quote Link to comment Share on other sites More sharing options...
FarmerSim Posted February 14, 2012 Report Share Posted February 14, 2012 I would be inclined to try what Timps says, above. I too have had this, always when you can't get one - so buy two!! Plus, if there was water and gunge kicking about in the carb, I would think about changing the oil in the sump - and cleaning the low oil sensor, which may be getting confused, if there is any water about..... ATB Quote Link to comment Share on other sites More sharing options...
lister1 Posted February 14, 2012 Report Share Posted February 14, 2012 I seem to remember we had some chinese copy chainsaws come in for repair and they had a similar probelm with the cheap copy plugs they had in. The plugs over heated really quickly. Oh if you replace the plug buy NGK or Champion. Quote Link to comment Share on other sites More sharing options...
timps Posted February 14, 2012 Report Share Posted February 14, 2012 I agree always get a decent make. But I had the same problems on my race bikes with good plugs, they do give up the ghost with time or abuse. Like Farmersim said it did happened to me when I could not get a new plug so I so stripped it there an then in the hope I could fix it without a new plug, but no joy, new plug job done. Quote Link to comment Share on other sites More sharing options...
Humour_me Posted February 14, 2012 Author Report Share Posted February 14, 2012 The oil in the sump was changed when I changed the low oil sensor in the link in my first post so don't think it's that. I washed the tank and dried it all out when I put fresh fuel in. Looks like it could be the plug feel a bit stupid cleaning it all out so many times now. Can the plug be purchased from a car parts store or is it some thing smaller? Quote Link to comment Share on other sites More sharing options...
boxlock Posted February 14, 2012 Report Share Posted February 14, 2012 it will defo be the plug, most car part shops should keep them. if not they will be able to order one Quote Link to comment Share on other sites More sharing options...
Ratman2 Posted February 14, 2012 Report Share Posted February 14, 2012 The oil in the sump was changed when I changed the low oil sensor in the link in my first post so don't think it's that. I washed the tank and dried it all out when I put fresh fuel in. Looks like it could be the plug feel a bit stupid cleaning it all out so many times now. Can the plug be purchased from a car parts store or is it some thing smaller? GKN BPR6ES and any car spares shop will stock them. Quote Link to comment Share on other sites More sharing options...
Ratman2 Posted February 14, 2012 Report Share Posted February 14, 2012 I would be inclined to try what Timps says, above. I too have had this, always when you can't get one - so buy two!! Plus, if there was water and gunge kicking about in the carb, I would think about changing the oil in the sump - and cleaning the low oil sensor, which may be getting confused, if there is any water about..... ATB Ere!!!!!!!!! It was me who thought of it first :P Chinese spark plugs are about as useful as a bottomless pan. Quote Link to comment Share on other sites More sharing options...
timps Posted February 14, 2012 Report Share Posted February 14, 2012 Look for a local motorbike shop or Halfords should do them, from memory it's something like NGK BPR 6ES. But your best bet is a motorcycle dealer. Quote Link to comment Share on other sites More sharing options...
Humour_me Posted February 15, 2012 Author Report Share Posted February 15, 2012 Ok guys well I got a new spark plug today couldn't get a NGK could only get a denso. I promtly went and put it in the rotavator and tried to start it. After a couple of pulls it backfired and started at the same time. I left it to warm up for a minute or so and took the choke off. As soon as I engaged the belt it stalled and you guessed it, it wont start again now. The plug that come out looked like the carbon fouled one on this page My linkI tried it with the air filter off just to see if that was clogged but still no joy. Looks like I'm back to square one. lister1 is it still worth checking the gaps? If it is i will do it friday. So any more ideas anyone? Quote Link to comment Share on other sites More sharing options...
bedwards1966 Posted February 15, 2012 Report Share Posted February 15, 2012 It would be a sensible idea to check the valve settings, it should be done occasionally anyway... As it seems to be having problems when it's warm it could be the valves causing the problem, perhaps staying partly open when warmed up. If the plug is fouled with carbon then it is running too rich, how long was it running without choke, it shouldn't need long with the choke on. It may be putting too much fuel in, that can cause issues. It's hard to say without seeing it. Quote Link to comment Share on other sites More sharing options...
Humour_me Posted February 15, 2012 Author Report Share Posted February 15, 2012 It was running maybe a minute with the choke them another with out before I started rotavating. When its running it seems to run really well. Will check the valves on Friday. How would you know if they are sticking. I don't think you can change the mixture on this carb? Thinking about buying a new carb, but dont want to keep buying parts with out it fixing it. Quote Link to comment Share on other sites More sharing options...
magman Posted February 15, 2012 Report Share Posted February 15, 2012 Sounds like fuel starvation to me , have you checked the fuel intake to the carb Had the same problem with a briggs and stratton the intake pipe was rusting from the water in the old fuel Quote Link to comment Share on other sites More sharing options...
Ratman2 Posted February 15, 2012 Report Share Posted February 15, 2012 (edited) It was running maybe a minute with the choke them another with out before I started rotavating. When its running it seems to run really well. Will check the valves on Friday. How would you know if they are sticking. I don't think you can change the mixture on this carb? Thinking about buying a new carb, but dont want to keep buying parts with out it fixing it. Next time you have it running, as soon as it stops take the plug out and check the spark, it should be a nice fat blue spark. Those ****** clone engine have lots of problems with ignition coil breaking down. Edited February 15, 2012 by Ratman2 Quote Link to comment Share on other sites More sharing options...
Humour_me Posted February 15, 2012 Author Report Share Posted February 15, 2012 Dont think it fuel starvation. The carb is spotless inside no rust any where. I put I new fuel line on the other day too as I had some around and there looked like what could have been some tiny holes in the old one. Filter in the tank has been cleaned nothing blocking that. I just looked on ebay and can get one for £110 spent about £40 already. Thinking of buying a new one dont really have £110 though. Quote Link to comment Share on other sites More sharing options...
lister1 Posted February 15, 2012 Report Share Posted February 15, 2012 Ok have you cleaned the main jet in the carb? If I'm thinking right, your carb float is doughnut shaped and it hinges on one side. There is a spigot that runs through the middle of the float doughnut hole. If you look up the spigot there is a brass jet that is screwed in that spigot and behind that screwed in jet there is another jet that should come out when you unscrew the first one. Make sure you remove and clean these. They have tiny holes in. They get gummed up with old fuel. When fuel is left for a long time it goes like varnish. That would be my first port of call. If it partly runs there isn't much wrong with it. Quote Link to comment Share on other sites More sharing options...
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