Ploughman Posted September 4, 2023 Share Posted September 4, 2023 Ace, if you are able to share the manual it would be a great help. The mower is a GS 30" mastiff serial 00493 I did sell my mark2 36in from 1980 , but kept one 36 in which is a difficult wrestling match, and this 30inch ride on with GS300 MAG engine , does have electronic ignition. It is the GS ( ride on) that has the trouble Quote Link to comment Share on other sites More sharing options...
Ace Posted September 4, 2023 Author Share Posted September 4, 2023 @Ploughman Does yours exhibit the same symptoms as in my first post? We also have a governor but doubt the control through a link to the carb could induce the symptoms after ten+ minutes use then reset once rested for 15 minutes🤔 Quote Link to comment Share on other sites More sharing options...
Ace Posted September 4, 2023 Author Share Posted September 4, 2023 Ours is an older 36" Ransomes ride on and doesn't have electronic ignition. MAG 1023 1035 1040 1045 SRL manuel.pdf Mastiff parts list.pdf Mastiff operator instructions.pdf Quote Link to comment Share on other sites More sharing options...
Ploughman Posted September 4, 2023 Share Posted September 4, 2023 Ace, very many thanks for your help with the manuals. Will download shortly. Yes, the symptoms are exactly as per your video. But I imagine that the electronic ignition also requires a coil, and maybe even a condensor ? In fact, I did have that model, and I notice your trick with the weights, which is a good idea.I had a lead pipe across the front arms at the time,only issue is turning after short runs, and our grass is bumpy ! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted September 5, 2023 Share Posted September 5, 2023 I assume you’ve looked at all the earlier suggestions but have you tried removing the fuel cap to eliminate a blocked vent? The symptoms could suggest fuel starvation. Quote Link to comment Share on other sites More sharing options...
Ploughman Posted September 5, 2023 Share Posted September 5, 2023 Hi Martin, thank you for checking on this. And very good to be able to join your forum on a shared problem. I agree, all points to fuel starvation , so efforts so far have all been towards that, including air jetting out the filler cap. The issue is associated with being hot, or a passage of time ( eg filler cap, blocked filter, jets ) . I have a neon light, so if I can see that when she is hot it will help the diagnosis before attempting access to electrics. I have an old home-made model aircraft, with ic engine and ancient controller all for "renovation" - would there be interest on your forum somewhere ? Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted September 5, 2023 Share Posted September 5, 2023 Mulberry wine anyone... Have you ruled out loss of HT spark when the machine plays up ? Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted September 5, 2023 Share Posted September 5, 2023 Difficult to say whether your model would be of interest Ploughman but if you post some pictures in a new topic we can give you some idea. Quote Link to comment Share on other sites More sharing options...
Ace Posted September 5, 2023 Author Share Posted September 5, 2023 I have a neon cap but can't see anything in daylight 😥. Having another go with it tomorrow. Doubt total loss of spark as it ticks over, sounds/feels as though spark/timing is out when hot. My money is on condenser/coil for ours. 1 Quote Link to comment Share on other sites More sharing options...
Ploughman Posted September 11, 2023 Share Posted September 11, 2023 Morning Martin,Ace, Rich . Thank you for your further suggestions. I have attached a video clip of the MAG GS300 engine which reluctantly started this morning ( normally second pull ), then responded OKish, did go to main jet, but then died on asking more throttle from the idling position. The neon light seems to light up OK , and there is still spark even when the engine is dying, I think ?? Glad of your views on the light indications. My limited knowledge points to maybe not electronic or electrical after all. The time taken to failure at higher operating throttle has reduced over a period months. from 30 mins to 15 mins, then 5 mins or so, but this morning was less than 2 mins. So engine was relatively COLD. After assuming coil or condenser ( has new NGK BP6ES) , my suspicion is sooty valves ( but no engine smoke ). All thoughts very welcome. I have cleaned out carb several times, removed jets etc, changed fuel, inserted filter. As engine was cold, no time for any excess heating up of the air/fuel mixture although engine has in the past run hot. I will send details of old model plane and bits separately many thanks Ploughman 1782913265_lowerrestrimmedMAGGS300stallonmainjet11_09_2023.mov Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted September 11, 2023 Share Posted September 11, 2023 Hi ploughman, Vidio doesn't seem to work... If you have a manual please post a link to save time like CDI ignition, flywheel mag ign, gravity feed fuel supply etc... Those red neon plug caps... Flash may be dim/feable at cranking, intensity grows when engine starts, grows brighter with revs, rate of change... If flash bright with revs and reduces with loss of revs, that's a reducing rate of change. If flash reduces at fixed revs, breakdown in ign system. You say not heat related today... Compression good at cold and warm and hot ? Even a "gloved thumb test" will suffice but either kill ignition or safe sparks, wide open throttle ideally To clean carb start at the fuel filler cap, vented..... A pdf of the manual and/or parts book exploded views will save time and lots of questions. How is oil level by the way ? There are some fake ngk spark plugs about, imperfect stamp markings on metal body is an indicator... Fuel filter, do a flow test, does fuel flow slow down or even "hang" ? Quote Link to comment Share on other sites More sharing options...
Ace Posted September 11, 2023 Author Share Posted September 11, 2023 (edited) Sorry I can't access your video😥 Griff beat me to it. Sorry! We could not locate the item you are trying to view. Edited September 11, 2023 by Ace Quote Link to comment Share on other sites More sharing options...
RottenRow Posted September 11, 2023 Share Posted September 11, 2023 Video works fine on my PC, perhaps it's down to certain versions of Windows etc. The neon in the plug lead looks like it's glowing well, but it's difficult to tell what happens first at the point the engine stops... does the spark 'go out', stopping the engine, or does the engine stop running, causing the spark to go? Perhaps you could make a similar video, after the engine has died, pulling it over with full throttle to see if it sparks then. I wonder what the metallic ratting sound is when the motor is accelerated. Pinking perhaps, which could indicate a possible problem with the electronic timing advance. It might be a silly question, but that brass fuel tap is in the vertical position marked '0'; I assume that is in the on position? Brian. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted September 11, 2023 Share Posted September 11, 2023 I wondered that last point too (video fine on an iPhone) There’s plenty of fuel in the filter - is this before or after the tap? Are you using fresh fuel? Modern petrol can go off very quickly in intermittently used equipment without adding a stabiliser, especially standard unleaded which may only last a few weeks. Maybe why it’s worse now than when last run? Also, is the fuel piping ethanol resistant? It might be breaking up internally and restricting fuel flow. There are a couple of moments towards the start of the video where the neon goes dark - maybe pointing towards a fault in the ignition system. Quote Link to comment Share on other sites More sharing options...
Ploughman Posted September 11, 2023 Share Posted September 11, 2023 I have saved vid as MP4 suffix, hopefully more accessible now sorry for convenience for non-Mac users. Thank you all for valued comments. Fuel tap may refer to "Open" and "shut" , but will double check. Filter is recent addition to ensure that fuel is clean. It is after the tap however, gravity feed. Can see the petrol running through into the filter where it hits the magnet . I have had it running out of the pipes - it just keeps running with no hold ups - all of which have been replaced with new fuel pipe, as I was concerned that fragments of old pipe could have been blocking jets. Have tried emptying out all fuel, replacing with Aspen 4 . Then changed back to standard 95 octane ( just purchased ) as there was no benefit and might cause unforeseen issues with neoprene or other seals, eg the needle seating. Fuel cap is very clean. Unfortunately, I do not have manual for this particular engine ( GS300 7.2 HP Electronic ignition ) , as Ransomes used Briggs, and also Honda whereas this is a Swiss MAG , later rebadged as Kubota mechanical rattling is because I had revs above idle and the centrifugal clutch starts catching and ringing like a bell. I will start her up again, wait till fails and attempt video when pulling the cord, when assistant available, as video was not a success with one hand pulling ( 7.2 HP ) and the other pointing at the neon ! I think that could be very instructive. She will definitely not start again once failed until cold. There is a brief no-glow at the first call for full throttle. Does seem to be sparking as engine dies however. Neon Light intensity and frequency seem to correlate with revs. 1613509510_lowerrestrimmedMAGGS300stallonmainjet11_09_2023.mp4 Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted September 11, 2023 Share Posted September 11, 2023 (edited) Fuel filter with a magnet, please where did you obtain that please ? Gravity feed, any arrows on the filter, is it upsidedown ? The fuel tap, does it have a "reserve" position and Is it fully on ? Edited September 11, 2023 by Rich Griff Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted September 11, 2023 Share Posted September 11, 2023 Also the fuel tap has a sediment trap, doesn't look clean ? So flashes seen on your HT tester but very poor internet here. Off to town so will look again on a proper computer... Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted September 11, 2023 Share Posted September 11, 2023 Wow, soooooo much more to see on a proper screen and warp speed computer, buy no sound ( library ).... I would call that HT "intermittent"..... Can you post a parts exploded views ?? Extra filter is on correctly. Fuel tap s for stop ? O for on, 8 for reserve ???? Is that sediment trap full of water, they usually have a brass filter screen as well. How is ign killed ? Handle bar kill switch or on LL SW on throttle cable plate ? Again parts exploded view would help, probably wasted spark system, HT coil above flywheel, one HT lead, one ign kill wire ( earth to kill or earth to enable ? ). This kill wire blowing in the breeze ????? On way back home Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted September 11, 2023 Share Posted September 11, 2023 Correction, intermitant loss of ht. Quote Link to comment Share on other sites More sharing options...
RottenRow Posted September 11, 2023 Share Posted September 11, 2023 Another thing to check is that the engine still has compression once it has got hot. When it is hot and won't restart, take the plug lead off and turn the engine over slowly and listen at the exhaust (and possibly the carb.) for air hissing out. The valves can gradually recede into the valve seats, this reduces the clearance until it is minimal at cold but zero once hot (due to expansion of the valves). The affected valve (usually the exhaust valve) then doesn't seal and you end up with no compression (and no depression to draw in the fuel/air mixture). One the engine cools down, the valves shorten again and the cycle is repeated. If the clearance is too small, it can apparently be reset by carefully grinding a small amount from the end of the valve stem. I believe 6 and 8 thou. are the correct clearances for inlet and exhaust respectively. Brian. Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted September 11, 2023 Share Posted September 11, 2023 Home, home again, I like to be here when I can, as long as I don't loose those dam keys... Vacuum fuel tap by chance ? A parts book would really help, exploded views show a lot..... Quote Link to comment Share on other sites More sharing options...
leccyflyer Posted September 11, 2023 Share Posted September 11, 2023 Not a topic on which I have anything in the way of experience to aid the troube shooting but I feel that I must point this out. Rich Griff - you frequently post multiple follow up questions and repeated requests for the thread starter or those contributing to post extra infomration, manuals, diagrams, photographs, videos, instruction sheets, exploded views etc. These must number in their dozens and are there in almost every thread that you post in. In stark contrast you virtually never post any information that might be requested of you - it very much looks like you just completely ignore those requests. 1 Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted September 11, 2023 Share Posted September 11, 2023 A picture is worth 1000 words I find telepathy very unreliable, just like the internet here, but In town the internet WiFi is good and in the library, along with a big vdu, it's fantastic, warp speed connection and I can print stuff off as well, all on a free bus pass, the best birthday present you will ever get imho. Try explaining for example how to assemble the choke mechanism on say a cm400t in words. CMSNL.com may help with the exploded views, terminology, part numbers and actual pictures of the parts concerned, not easy. Asking for a schematic of say a particular tx/Rx, two pictures, explain them in under 2000 words if you can, good luck with that one. Sometimes that's the only way, concerned parties looking at the same map as it were. There are many Tal y Bonts. Anyways ploughman, vacuum fuel tap maybe ? Try disconnecting the wire to the kill switch when engine is running. Did it stop when wire disconnected ? Two wires to the kill switch or just one ? A parts exploded view and wiring diagram would be very informative and helpful. Quote Link to comment Share on other sites More sharing options...
leccyflyer Posted September 11, 2023 Share Posted September 11, 2023 4 minutes ago, Rich Griff said: A picture is worth 1000 words I find telepathy very unreliable, just like the internet here, but In town the internet WiFi is good and in the library, along with a big vdu, it's fantastic, warp speed connection and I can print stuff off as well, all on a free bus pass, the best birthday present you will ever get imho. Try explaining for example how to assemble the choke mechanism on say a cm400t in words. CMSNL.com may help with the exploded views, terminology, part numbers and actual pictures of the parts concerned, not easy. Asking for a schematic of say a particular tx/Rx, two pictures, explain them in under 2000 words if you can, good luck with that one. Sometimes that's the only way, concerned parties looking at the same map as it were. There are many Tal y Bonts. Anyways ploughman, vacuum fuel tap maybe ? Try disconnecting the wire to the kill switch when engine is running. Did it stop when wire disconnected ? Two wires to the kill switch or just one ? A parts exploded view and wiring diagram would be very informative and helpful. I'm not speaking of whether images are useful or not, I'm speaking of the asymmetry in your repeated requests for ever more information, and repeated questions asked of the thread starter and other contrasting with your reluctance to ever answer a question that you are asked by other members here. Quote Link to comment Share on other sites More sharing options...
Ploughman Posted September 11, 2023 Share Posted September 11, 2023 Rich, The fuel tap has an integral sediment bowl, and as you expected, a simple mesh coarse filter. It has all been cleaned out, looks dirty because the bowl is old and lost is translucency. Not sure what you mean by vacuum the fuel tap. It is cleaned out and flows freely. There is no vacuum forming. The engine switch off is the ignition key. it seems to work OK, engine on and off. Definitely does not start if key is in off position !! Unfortunately, much as I would like to have a parts diagram, I do not have one. Ace kindly supplied manuals, but my engine is later MAG model and different. is looking more like valve issue, and I will look at compression etc It has been a long established problem, probably there when I purchased the machine from a mower machinery supplier Quote Link to comment Share on other sites More sharing options...
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