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Bandit starting problem (when wet?)


marksmith
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Hi folks,


Suzuki GSF600S Bandit, 1999 'T', 35,000 miles, usually reliable.


Yesterday morning, after heavy rain and not being used for two weeks over Christmas, my Bandit wouldn't start properly. It cranked strongly but would not run properly. It would fire and just about idle, but would die after a few seconds. After some playing with the choke I got it to idle, but giving any amount of throttle would stall it. After several minutes idling it still wouldn't work, and with all the messing around I managed to flood it and couldn't start it at all.


AA came out last night (while it was raining and after heavy rain during the day) and, after a bit of coupe of false starts while the flood cleared, it started and ran perfectly. Revved fine, choke behaved as you'd expect, really no problem at all. Ran it for 15 mins or so and switched off.


This morning - guess what? Exactly like yesterday morning.


Any suggestions please? I'm unsure whether it's related to the wet - wet hasn't been a problem before (I use it as a commuter) and it was wet last night when it ran OK - but thought it best to mention.


I'll try to have a look at it over the weekend - spark plugs and leads etc. - but grateful for any tips.


Thanks!

-Mark

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I had a 12 that did that it got worse & completely random, would start & run fine then another day kick over & nothing, turned out to be the live feed to the ecu ( a tech found this out not me ) new live feed & it started every flippin time

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When you get it started and it's ticking over is it firing on all cylinders?.....the symptoms do sound a bit like a weak spark. Spray WD40 over the HT leads....check the plugs caps....and also spray around the coils.....and check all the connections around there to make sure they are all tight and not corroded...... :wink:

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Try opening the fuel tank before starting the bike, the breather could get blocked from the rain creating a vacuum. I had a similar problem with my bike, I just make sure it's covered ;)

Thanks, will give that a try. I do sometimes cover it up but haven't recently. I can't cover it up at work so it needs to be reliable :-)

 

When you get it started and it's ticking over is it firing on all cylinders?.....the symptoms do sound a bit like a weak spark. Spray WD40 over the HT leads....check the plugs caps....and also spray around the coils.....and check all the connections around there to make sure they are all tight and not corroded...... :wink:

At one point the first morning it was very clearly running on less than 4. In the evening it ran smoothly on all 4. Thanks for the tips, I'll look at these things on the weekend, weather permitting.

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There are just underneath the exhaust headers if I remember correctly?. Pull the plug caps off and squirt some wd40 or similar in the holes and see where it leaks from. Hopefully one will be O.K. :mrgreen:


A common problem with the early bandits, not sure if the 650/1250 suffer the same issue as I've never seen one that close.

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Well the bike has been in the dry for three days and nights, but this morning again refused to start with the same symptoms - cranked strongly and maybe just a momentary fire, but then nothing -- so I no longer think this is wet related.


While disassembling I discovered the main fuel line was badly holed so I replaced that. Also cleaned up the LT connections to the coil. Measured the resistances of the coils and all good (a bit out, both HT coils about 46k - Haynes says 30-40k - but I suspect that's good enough). Tank back on and it started immediately - but would not rev and no1 pipe didn't get hot. (No4 was questionable, 2 and 3 definitely hot.) Fiddled about with throttle and choke a bit (repeatedly stalling and restarting, getting progressively worse) and now it won't fire at all.


The HT leads look good (no corrosion) and there is no sign of water in the spark plug holes. A spark plug attached to each lead sparks. Fuel is getting to the two inlets on the bottoms of the carbs. Air filter removed in case that was choking it.


I suspect it's flooded now, and I've flattened the battery trying to start it, but I am sure there is another problem. It's like the mixture is so badly out that there's no combination of throttle and choke which makes it run properly, so just starting it results it it flooding. Something like that.


It's going to be a frustrating one to diagnose, I suspect... Advice much appreciated!

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What are your valve clearances like?


BTW it can be difficult to assess how powerful the spark is by looking at them firing outside of the cylinder, inside the combustion chamber it is much harder for the spark to jump the gap due to the density of the combustion mixture as it's being compressed. I only use this method to help diagnose a bike that won't run full stop, not one running rough. The ignition system is far more accurately tested using an analyser such as a scope, not much help to you I know but it is probably worth taking to garage to look at.


Maybe you have carb issues, but first check the valves.

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I did the valve clearances a couple of years ago and they were surprisingly good. I don't think they would suddenly have gone so far out that it wouldn't start - they'd gradually drift out, wouldnt they? It was running fine before Christmas.


Carbs sounds interesting though. I wonder whether a float has seized or a needle gummed up. They've never been serviced or cleaned. Do you really have to replace the rubber gasket on the bowls? They're almost as expensive as the carbs...

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If you are careful, just get the carbs off, take the float bowls off and clean the jets through with some carb cleaner spray. There will probably be rusty crap sediment in the bottoms of the carbs, there were in mine. If you are careful, you shouldn't need any bits to do a clean, but a rebuild kit with new seals etc is not going to do any harm.

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Well this is doing my head in now. Left it overnight on charge, tried again this morning - would not fire.


Spark plugs out for about half an hour, replaced with some old (but good) ones. Still will not fire.


Removing the carbs requires removing the air box required removing the seat cowl requires removing the luggage rack. If I were confident that it would help, I'd do it -- but I am struggling to believe that all four carbs went from being fine to being so bad the bike won't start, simultaneously.


I wonder how happy the AA man would be to come back now the bike is in pieces...

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Doesn't work like that.


You get a build up of crud in the carbs and then one day a big lump of crud gets sucked into a jet and bingo. bike runs like poo.

Another thing to check is inline fuel filter. If they get old, the paper ones can start gradually feeding bits of paper through into the carbs, which again will make it instantly stop working.

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Thanks very much for the advice. I'm summoning up the courage to remove the carbs and clean them.


Hunting around youTube yesterday I saw a video of a Bandit cold start, and it's much nicer than mine has been for several years - so I think I've got used to compensating for it gradually getting worse. I have a vain hope that I might be able to make it run like that again -- although getting it to start at all would be an achievement at the moment.


(My concern with fiddling with lots of different bits is that I could inadvertently introduce a second fault, and finding two faults would be almost impossible. Always prefer to mess with one thing at a time, returning to something working each time - then when it goes wrong, you know where to look.)

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Latest news: took the carbs off yesterday to clean. Drained them - and they were half full of water. Drained the tank and it had a good half litre of water in the bottom. So that would appear to be the problem.


Apart from that they were very clean - so blocked jets or crudded up needles etc. Gave them a good clean out anyway.


Today's job is to work out why water's getting into the fuel. Presume some problem with the drain around the filler cap.

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