curvy fuel line bleed

After a change of engine, i'm now trying to start her up, but can't get the fuel to flow properly down the line from the tank to the vacuum pump.

I can suck it if i suck HARD, and get a gob full of petrol, but was wondering if there is an easy way to prime it so i don't need to taste that lovely stuff anymore!

Engine starts if i put fuel directly into carbs, but obviously runs out when fuel is spent. Not sure if i'm just not getting enough crank pressure to start the vacuum cycle, or what,

anyone got any ideas?

J

[Sid Squid]

Shouldn't require any priming - the pump and lines will fill themselves if it's all working properly.

Check all the pipework for leaks and damage.

[maviczap]

Have you got the pipes attached to the right bits.

If you suck on the vacum pipe to the pump, fuel will flow, without you having to suck on the fuel line. Then you can get the engine turning over

Make sure you've no kinks in the lines either

But as SS said check for leaks first

yeah, tried that, can't see anything...

Check that the tank breather isn't blocked...

ok, update is that it starts with persuasion, but is lumpy and heck. This can be partly explained by old plugs and oil, and needing to fully tighten the exhausts, but any further ideas?

Originally Posted by klu

Check that the tank breather isn't blocked...

the sv tank has no breather its a sealed vessle

check the vaccum pipe that goes from the rear carb to the vaccum fuel valve and check the pipe that goes from the rear cylinder manifold to the secondary vacuum fuel valve mounted on the right side frame

ok just noticed your recent post
if your plugs are black and sooty clean then and heat the electrodes up to free them of any soot

[yorkie_chris]

Originally Posted by madandy

the sv tank has no breather its a sealed vessle

check the vaccum pipe that goes from the rear carb to the vaccum fuel valve and check the pipe that goes from the rear cylinder manifold to the secondary vacuum fuel valve mounted on the right side frame

How can it be a sealed vessel if petrol still comes out?
There is a breather hole in cap.

Yea check that vacuum pipe, try suck on it with pipe from pump to carbs disconnected, fuel should pour out.

its a drainage hole that stops rain water from collecting undrneath the fuel filler cap it drains to the right side of the bike near the clutch cover is also known to block up due to the rubber hose kinking when the tank is in the lowered position
its also connected to the overflow for the cooling system.
there is no breather in the tank thats why when you take the cap off youll sometimes hear a woosh of air
hissing will suspect the cap seal has failed which is an mot failure

diesel tanks have breathers to stop air leaks forming

petrol tanks dont as they are pressurised