Yamaha 125cc Vity - intermittent starting problem

[ForumRick]

My Yamaha Vity 125 2013 has an intermittent problem where it doesn't start.

The symptoms: electrics seem to be fine as dashboard lights up when the key is turned. When ignition pressed the bike makes a sound where it is turning over but no sign of it kicking into life with fuel igniting.

The bike is otherwise fine, first occurred immediately after MOT and Service and over the last 6 months, I have not had any other problems. Oil levels look fine. The issue has occurred with a full and low tank of petrol so don't think it is affected by this. The issue has occurred at different times throughout the day and in differing weather conditions from cold winter to very warm.

The issue has occurred in three scenarios:
(1) When I mistakenly tried to start the bike with the kickstand down, the bike starts up and then immediately cuts out as it should as there is a sensor. When I did this, each time the above symptoms would occur and I would not be able to start it until the next day... I suspected flooding engine but don't know for sure.

(2) Since we had the warmer weather this week, the issue has reoccurred with a vengeance. It has started fine in cool mornings but failed to start in the afternoons. Someone said there is a history of Yamaha's having fuel pumps affected by hot conditions that can cause this but...

(3)...it has also occurred a couple of times quite randomly. No obvious cause. Weather conditions cold, not freezing/wet just a normal cold winter's day. The garage and I are stumped as to the cause. An independent mechanic also couldn't find any obvious problems with the bike.

I'm not sure if it could be one problem causing all three scenarios or if I have multiple issues.
Any help or ideas very welcomed!!
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A Learner and willing to learn!

[jaffa90]

"""first occurred immediately after MOT and Service and over the last 6 months,""
Does this garage know about this? (6 months).
If it was my bike i would fit a visible inline spark tester and if the sparks are ok then an inline fuel pressure gauge.

[ForumRick]

Yes, the garage I bought it from is reputable and they witnessed it happen on the first occasion. They thought they'd flooded the engine. They have been kept informed over the last 6 months of issues and have offered to have it back again to work on but it sounds like they are as lost as I am with it.

I'll pass on your advice, thank you.
____________________
A Learner and willing to learn!

[ForumRick]

As an update.. I took the bike to the mechanic today and the problem occurred whilst I was there so he was able to run some diagnostics.

He concluded it is caused by the fuel pump not priming. Hopefully that's problem solved but does that sound right? would anyone challenge that?
____________________
A Learner and willing to learn!

[Easy-X]

My car's pretty much doing the same thing: it's the fuel sender in the tank. Just waiting on a new one. In the mean time...

Try hitting it with a hammer, worked for me

(Basically the motor just needs a little nudge to get started.)
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[jaffa90]