Phil_P Posted January 4, 2009 Share Posted January 4, 2009 Hi all, my Adventure F3 with electric start and HEIS has become unstartable. The spark seems to be very weak, although it does seem to be present. After a bit of cranking, the spark plug becomes saturated with fuel. I have changed plugs, and plug caps, the carb has been recently serviced with all new diaphragms, filters and gaskets, and today I have swapped the carb needle, just in case it was leaking and flooding the plot. The battery has been fully charged, and I've even jumped it off a car battery. While cranking this morning, I got a couple of backfires but no start. It wouldn't even start after a squirt of 'Easy Start' The engine has progressively got worse at starting since I got it, although usually, once warm it would start after a few cranks. The resistance on the coil seems about right, and there is no evidence of the HT tracking round the coil or plug lead, but I've added a bit of sealant and shrink sleeving just in case. The flywheel generator seems to be doing it's job, as when the motor has been running the battery has been get recharged. I have an alternative coil on order to try swapping out, but the 'black box' is completely sealed and potted in resin and I don't want to order one of them unless I can truly diagnose it as faulty. Quote Link to comment Share on other sites More sharing options...
morgy Posted January 4, 2009 Share Posted January 4, 2009 Have you check the spark from the plug??? I know you said you have changed it Or if the plung is getting wet with fuel then the mix might be out but a fair way... Quote Link to comment Share on other sites More sharing options...
t_andrews Posted January 4, 2009 Share Posted January 4, 2009 Your backing plate may have moved: http://www.southernskies.net/page_info/ ... stall.html See Step 9 May also want to check the continuity on your ignition enable circuit. A bad switch or high resistance in the line somewhere can cause pitifully weak spark too. Ask me how I know... Either one could explain progressively worsening starts. Quote Link to comment Share on other sites More sharing options...
Phil_P Posted January 4, 2009 Author Share Posted January 4, 2009 Having read more, it would seem it's not a HEIS but a standard CDI electronic ignition. Don't know if you can get HEIS with a charging circuit. I have checked for spark at the plug, and it's present but not strong. Mixture has been fine, was managing to start up till new years eve when it ran ok. Seem to have a full battery voltage at the CDI unit, and good continuity between CDI/coil/starter coil/ground and power. Kill switch is correctly open circuit unless pressed. Quote Link to comment Share on other sites More sharing options...
t_andrews Posted January 4, 2009 Share Posted January 4, 2009 Kill switch grounds correct? If so, check your arm switch - the circuit that enables feed voltage to coil. If this circuit has high resistance (corroded switch, wire, whatever) it can limit coil feed voltage and leave you with worsening spark. It can still pass a continuity check with high resistance like a stove element... Ohm reading on that circuit should be near zero. You said coil resistance was nominal - what about lead wire? Also, the screw fitting inside the wire that hooks to plug can unscrew or get mucked with after pulling it off a plug N number of times. At least you're narrowing cause down. Quote Link to comment Share on other sites More sharing options...
Farmer_Dave Posted January 4, 2009 Share Posted January 4, 2009 I have a standard coil spare Phil, if you need to try it. Can post. You can have charging with HEIS as far as I've been told. I didn't bother cos the one I fitted it to has pull start only. BTW. The reason my mates wouldn't start, and only backfired, was a broken woodruff key on the crank / flywheel. Local tool hire centre had a box of them @ £ each Dave Quote Link to comment Share on other sites More sharing options...
t_andrews Posted January 4, 2009 Share Posted January 4, 2009 I had not heard of that ever happening and so dismissed it as a suggestion. It would toast timing though. Quote Link to comment Share on other sites More sharing options...
Phil_P Posted January 4, 2009 Author Share Posted January 4, 2009 I had not heard of that ever happening and so dismissed it as a suggestion.It would toast timing though. It would indeed, but you would still get a healthy spark, just at the wrong point in the cycle (as long as the rotor wasn't stationary). My spark just isn't there now. I remembered that I had an aged oscilloscope down the shed, and dragged it out and hooked it up. From what I can make of the readings (as I don't really know how to use it properly), I'm only getting 3 volts on the primary to the coil from the CDI unit. This would certainly explain a feeble or non existent spark, as you might expect anything up to about 300 volts being delivered at this point from a healthy unit. Quote Link to comment Share on other sites More sharing options...
t_andrews Posted January 4, 2009 Share Posted January 4, 2009 Would you though? Get a good spark? Isn't spark generation dependent on the woodruff spinning one bit inside the other? It would certainly explain both weak spark and timing. Also, when central shaft heats up with runtime, it would grab the sleeve better, making a warm start easier? Speculating, because I don't have to go check these things Quote Link to comment Share on other sites More sharing options...
Guest Posted January 5, 2009 Share Posted January 5, 2009 i have a friend who bought an f3 with solo and he uuses an 18 v battery when i asked why he said it is what it says in the book and 12 v will not turn it quick enough to generate a good spark, if you usin 12 v it might be an option to try 18 v Quote Link to comment Share on other sites More sharing options...
Phil_P Posted January 5, 2009 Author Share Posted January 5, 2009 That might be a possibility Leo, but as it HAS been working, and originally was even starting easily and reliably with the factory supplied 12 V battery, there must be an underlying problem, culminating it would seem in terminal failure. There are essentially only four parts to the ignition system; 1) Battery 2) CDI unit 3) Ignition pulser 4) HT coil By a combination of elimination and diagnostic tests, it looks very much as though the finger is being pointed at the CDI. As a rule, the smaller the HT coil, the greater the driver voltage required, hence using CDI for the diddy coil on the F3. It should be chucking out about 100 to 300 Volts, which, judging by the coil resistances would get multiplied up to several tens of kV. On test with the oscilloscope, there seemed to be only 3 Volts at this point, which would only yield about a thousand volts on the HT side, which would never be enough. Also, with electronic ignition, as the primary coil voltage is being produced by the battery and amplification in the CDI, the speed of rotation is relatively unimportant. The CDI only needs to see a small trigger pulse to activate, and only a very low RPM will produce this. Quote Link to comment Share on other sites More sharing options...
Guest Posted January 5, 2009 Share Posted January 5, 2009 ohh i dont know as i aint a electrical engineer hope it works out tho for you. i had a solo and it always took some startin very weak spark Quote Link to comment Share on other sites More sharing options...
Phil_P Posted January 9, 2009 Author Share Posted January 9, 2009 Adventure have been in touch and I'll have my new parts by Friday of next week hopefully. Going to have to do a bit of re-wiring, as they have changed the connections to the CDI. I've ordered a new prop shaft main shaft too, as the bearings in the pulley had been spinning on the shaft (as opposed to the two parts of the bearing turning relative to each other). This has worn the shaft so the bearings are loose, although I've fitted a strip of shim steel to take out the play on a temporary basis. Going to try some hybrid ceramic bearings in the prop shaft pulley if they turn up from the USA. Better wear characteristics and heat resistance is claimed. Can't afford to go the whole ceramic hog. Will report on these when I get them up and running. Quote Link to comment Share on other sites More sharing options...
outkast Posted January 14, 2009 Share Posted January 14, 2009 Have you solved the problem? reason I ask is I have just had the exact same happen to mine, I took the plug out, disconected the killswitch and now I have a healthy spark, have you definately eliminated the killswitch as a problem? Quote Link to comment Share on other sites More sharing options...
Phil_P Posted January 14, 2009 Author Share Posted January 14, 2009 Yup, killswitch is fine. It is open circuit when at rest, short circuit when pushed. Quote Link to comment Share on other sites More sharing options...
prichardson Posted January 21, 2009 Share Posted January 21, 2009 Had similar problems last year and spent hundreds replacing needless components. Is the gap between the coil and magneto correct and are they NOT touching at all? Best way to measure the gap is with a business card believe it or not. Card between the coil & magneto then tighten the coil. Give this a go and let me know because it seems exactly like my old problem. Paul. Quote Link to comment Share on other sites More sharing options...
Phil_P Posted January 22, 2009 Author Share Posted January 22, 2009 The system that Adventure use involves a four coil stator, three for generating power and one ignition pulser. The whole assembly is fitted as one, centrally, and there is no means to alter either the stator/rotor gap or the stator/backplate relative positions (so ignition timing is preset and fixed also). I have been exchanging emails with Emmanuel in tech support at Adventure, and it seems that my pulser coil resistance is too low, suggesting a partly shorted winding. Emmanuel has said that this would reduce the power delivered to the CDI to the point where a spark would not be generated. I am, as we speak waiting for a new stator. Adventure have been kind enough to allow me to return any components that I haven't needed, for full credit, so the CDI may be going back, as it's possible my original one may not be U/S as originally thought. Quote Link to comment Share on other sites More sharing options...
pauldeakin Posted January 22, 2009 Share Posted January 22, 2009 Phil, I expect you have already done this, but as you have the stator removed, check the magnets, I once had a similar problem to yours, and found that one of the magnets had a hairline crack that was barely visible. The symptoms were similar in that it was difficult to start, ran very rough and the output to charge the battery was weak. Paul D Quote Link to comment Share on other sites More sharing options...
Phil_P Posted January 26, 2009 Author Share Posted January 26, 2009 Parts arrived from Adventure today about 13:00 including a new stator and a second CDI, I have just finished getting it together. My stator was definitely U/S, as my original CDI produced a spark straight off. Bizarrely, the CDI that Adventure originally sent me is actually faulty, so that threw a spanner in the diagnostic work. Took it outside for a test, primed as normal and it started within about one full turn of the prop and settled into an idle that is more stable than it has been in a long time. I know it's very subjective, but I could swear it is pushing much harder than it has been in the recent past. If the spark has been weak, I may have been down on power for quite a while I guess. Now I've got the EGT sensor in the exhaust I can actually tune it properly now too. What's the forecast for tomorrow? Quote Link to comment Share on other sites More sharing options...
pete_b Posted January 26, 2009 Share Posted January 26, 2009 Good to hear you are back ready to go. Have fun. Pete b Quote Link to comment Share on other sites More sharing options...
outkast Posted January 26, 2009 Share Posted January 26, 2009 Had similar problems last year and spent hundreds replacing needless components. Is the gap between the coil and magneto correct and are they NOT touching at all? Best way to measure the gap is with a business card believe it or not. Card between the coil & magneto then tighten the coil. Give this a go and let me know because it seems exactly like my old problem. Paul. Paul, do you mean a ordinary cardboard business card? I have just fitted a new HT lead, plug cap and killswitch, I now have a good spark and fuel is getting through ok but it still wont start, I think the gap may be the problem. Cheers, Dave Quote Link to comment Share on other sites More sharing options...
prichardson Posted January 27, 2009 Share Posted January 27, 2009 Hi Dave, A very good engineer friend of mine sorted my gap problems out. Take a normal card (not plastic) business card and place it between the coil and magneto and then tighten the coil in to place. It's near as impossible to measure to within several thousandts of an inch (for me anyway). The business card trick is apparently used quite heavily in agricultural engineering circles and it did the trick with me. Card is far better than plastic because the card will bend around the circumference of the magneto. Give it a crack and let me know how you get on Paul. Quote Link to comment Share on other sites More sharing options...
outkast Posted January 27, 2009 Share Posted January 27, 2009 Hi Dave,A very good engineer friend of mine sorted my gap problems out. Take a normal card (not plastic) business card and place it between the coil and magneto and then tighten the coil in to place. It's near as impossible to measure to within several thousandts of an inch (for me anyway). The business card trick is apparently used quite heavily in agricultural engineering circles and it did the trick with me. Card is far better than plastic because the card will bend around the circumference of the magneto. Give it a crack and let me know how you get on Paul. Thanks mate, I will see if that works Quote Link to comment Share on other sites More sharing options...
Guest Posted January 27, 2009 Share Posted January 27, 2009 Now I've got the EGT sensor in the exhaust I can actually tune it properly now too. what is this? are they easily bought to tune them? Quote Link to comment Share on other sites More sharing options...
Phil_P Posted January 27, 2009 Author Share Posted January 27, 2009 Easy to come by, various prices. I'm using a small digital gauge from the States, and the sensor came off a cheap car EGT off that well known auction site. You then need a bush welding into your exhaust pipe, about 4 inches from the piston skirt and screw the probe into that. You then tune for max RPM and watch the temp. I believe 650-750 degrees Celsius is considered a normal operating range, and as they respond very fast, you stand half a chance of saving your engine if it overheats. The next part of the project is to have a warning light in my eyeline in the front of the helmet, that will come on in an over-temperature situation. That way, you don't have to spoil your flying by spending half your time looking at a temperature gauge. The low fuel sensor will be wired into the same warning system. Quote Link to comment Share on other sites More sharing options...
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