UPDATE: vapour lock? was floats, fuel pump, blocked fuel...

[talkToTheHat]

My 535 has an over-frame tank that gravity feeds a larger underseat tank. This then has a petcock beneath which routes fuel into a tube that runs back through the underseat tank, exiting on top, through a fuel filter, to a fuel pump beside the tank, then up to the first carb by a long hose. A translucent silicone hose connrcts the two carbs together.

Usually when I turn the bike on the fuel pump fires for maybe 3 or 4 beats before shutting off. Today it has been shutting off on timer and running faster like I am out of fuel or there is air in the system. I have done 50 miles since my last fillup so I should have that again until bone dry at the very worst, shaking the bike sounds like the underseat tank is nearly full. There is a small bubble in the silicone hose between the carbs, this does not appear to be moving, so fuel is not being pumped into the front carb, or flowing back from the top hose into the rear carb.

On draining, both carbs came out clean. I drained the rear carb first and the bubble moved so I don't think its floats.

I just changed oil and filter, air filter, and fuel filter.

Thoughts? Seriousness. Have done 30 miles or so on the bike today and bike has felt fine.

Could it be just heat soak into the fuel line causing vapuour lock?

What should I check next or is it panic and garage time?
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Bandit. does. everything.

[davebike]

Fuel tap ??
the electric main /reserve tap is a common source of problems on the e535 been left unused over winter ??
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Dave
NC750Xdct + others at work !
davebike1@gmail.com

[talkToTheHat]

This bike is used all year round as my daily transport. Unlikely to have layover specific issues. The dammned solenoid reserve only switches from main to reserve feeds, that is the night of the fuel take off from within the under-seat tank. Manual petcock was rebuilt in the autumn with new seals as it wouldn not shut off. I think I shall pull hoses and investigate this next.
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Bandit. does. everything.

[talkToTheHat]

Looked at it today on a cold bike. Fuel pump is dumping fuel out of the tank pretty efficiently. Hoses reconnected everything is behaving as normal. My current theory is partial vapour lock. The hose between the pump and the carbs is an r9 alcohol resistant high pressure thing and is routed in such away that it is in contact with the cylinder head. Is do not know if this is increasing the heat soak into the fuel, previously there was line with some kind of rubberised fabric overbraid. I am not sure whether it was stock but it was disintegrating badly inside.
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Bandit. does. everything.

[davebike]

Pipe touching head Had this problem with a Harley

Wrap it in two layers spiral wrap as used the tidy swingeing sorted the Harley

I have seen the "change over " tap block , stick half way neither on! etc worth using it on / res / on on every ride
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Dave
NC750Xdct + others at work !
davebike1@gmail.com

[talkToTheHat]

I flick the reserve switch from time to time as some kind of ritual to have it work when required. I try not to hit reserve though.

What do you mean by spiral wrap? I have several things that might meet that description and none of them seem the right thing. Do you mean exhaust wrap?

Opinion of local bike shop is if it runs OK and fueling seems OK then isn't a problem. Went to the supermarket via several other counties. Seems OK when running briskly, but heat soaks into the line when stopped. Suspect this could be an issue if I end up having to queue in traffic for a long time on a hot day.
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Bandit. does. everything.

[davebike]

Ok bulk trade supplier but you see what I mean you could use exhaust wrap but it would be a bastard to fit

https://www.beal.org.uk/electrical-products/spiral-wrap/cat_25.html
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Dave
NC750Xdct + others at work !
davebike1@gmail.com

[mysterious_rider]

Ideally if the hose goes near anything warm. On fuel injected systems I think you are meant to have a one way valve installed. Maybe worth a shot?
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KAWASAKIIIII

[talkToTheHat]

@davebike: you did mean what I think you meant, I might have some.

@mysterious_rider: Fuel injection systems run at high pressure and have their own quirks, importantly high pressure lines don't have such problems with fluids that have a high vapour pressure as the working pressure is much higher than vapour pressure. Here the pump mostly has to lift fuel about a foot, so the working pressure is pathetic. I am using a fuel injection one way valve in my brake bleed kit so I have an idea of how much space I might need to find. I shall see if that is possible.
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Bandit. does. everything.