Carbs/fuel problem

[Paul]

I've got a problem with my 400 Katana.
It starts straightaway on the button, no problem.
But then it runs dry about 50% of the time.
The first time it happened to me, I turned the tap to prime, saw fuel filling the in-line fuel filter & away I went - thinking there is a problem with vacuum fuel tap.
Next morning, bike starts immediately as usual, 1/2 mile up the road runs dry - I messed with the fuel tap turning it from prime to run to reserve & eventually the fuel flowed again & away I went.
Came to go home from work, started bike, looked at fuel filter, saw it draining, turning tap to & fro made no difference so I shook bike side to side, and fuel started to flow, away I went no problem.
So I keep getting this problem, & I am getting round it by either messing with tap, or shaking it from side to side, or another way that sometimes works - open the fuel cap.
I've just removed tank & tap from bike, there is a small puncture hole in the vacuum pipe so that probably explains the vacuum tap not operating.
I've drained the petrol from the tank through the prime position on tap - came out no problem.
Has anyone got any ideas as to what is wrong?

[KEITH KRAUSE]

I'd say you already found it... the bad vacuum line. I'd replace it and clean out the vent in the gas cap with carb cleaner. I'm not a fan of inline fuel filters either. If the tank is good inside, the stock petcock filter is all you need. If you still have the problem, I would inspect/clean up the petcock and see if that helps. You may have to rebuild it.

[Paul]

I thought it was the vacuum pipe, but why is the problem still there when it is on prime?
What I'm doing now is replacing fuel pipe & the vacuum pipe. I'm a bit suspicious of the in-line filter as well, but at least I can see if fuel is flowing!
Also I'm cleaning out the tank, there seems to be a lot of rust coloured sediment/dust in there. The petrol tap looks OK.

[KEITH KRAUSE]

I guess I read your post too quick. If you have rust particles building up, that will cause it. They can pile up and stop the fuel. Disturbing them by shaking, etc, can loosen them up temporarily no matter where they are.
The gas tank needs to be repaired. That's the real fix. The rust particles are probably plugging the petcock screen in the tank.

[Paul]

This is like dust (rusty coloured dust!), not flaky at all.
I've swilled the tank a few times and it's getting better (clearer petrol coming out).
There seems to be water in there as well - it's a wonder it was running at all if it is water!

[KEITH KRAUSE]

I've heard others here say they had flow problems even though the rust particles were "very fine". Cleaning the tank will help, but you need to get it Kreemed or ?

[Anonymous]

Clean clean clean is the way to go, that dusty rust can really buggar thing up... been there :x

[Paul]

Just an update.
I cleaned the tank, I can't understand where all the crap has come from - the inside of the tank is rust free.
I replaced the vacuum & fuel pipes.
Balanced the carbs with vacuum gauges.
And so far it is running so smooooooth!

[KEITH KRAUSE]

Glad to hear it! If the tank is in good shape, the rust could have come from the fuel gauge assembly? Also, I once cleaned out a gas cap vent with carb cleaner spray and was amazed at the amount of brownish-red fine dust that came out of it. Maybe it could accumulate in the tank over time?

[Paul]

No fuel gauge on this model!
I wonder if the bike had been "sabotaged" whilst the previous owner had it - she was a trainee manager for Sainsbury's (a huge supermarket chain) & she was in charge of the gas station. She told me she had a problem with staff.
The reason I got the bike cheap was that she couldn't get it to start & run.