Bandit 250 "runs out of fuel"

[vindy500]

So i got a new bandit, (a 92) and sometimes at higher speeds circa 110 it "runs out of fuel" like it just loses all power and i have to pull over and start it again after 30 seconds or so of waiting. it seems to do it less when set to reserve and sometimes only runs if set to prime, also when you "floor" it (twist it?) instead of accelerating smoothly like it should it just gets noisy. any ideas?

[xwhatsit]

It does sound like it's running out of fuel at sustained high revs. Basically the idea is to check it can piss out fuel as fast as it needs to. Check for:

Blocked tank breather
Blocked fuel tap, give it a good clean out, you can dismantle them easily enough
Blocked fuel line
Clean fuel rail/carb delivery system
That there's any crap at all in the tank or float bowls


Had the same problem with a very shitty FZR400 that was lying around for ages. Rust in the tank was blocking things up.

[vindy500]

i do wonder if its in the tap, because of it working better in reserve than in on. i opened it up today tho and didnt really know enough to do anything :) how would i go about cleaning it out? also there was air in the fuel filter, is that ok?

[MSTRS]

i do wonder if its in the tap, because of it working better in reserve than in on. i opened it up today tho and didnt really know enough to do anything :) how would i go about cleaning it out? also there was air in the fuel filter, is that ok?

Reserve should be worse, if it's a blockage in the intake, because it draws from lower than main. Air in the filter just suggests what we know already....the fuel is feeding slower than it's being used. I'd suggest it is a problem with the vacuum hose/system that opens the fuel tap when engine is running. The 'running well on prime' is a big clue...because the prime position bypasses the vacuum section in the tap.

[CookMySock]

If you shake the bike tank around when its hot does it hiss from out under the fuel cap? Does the fuel cap let a rush of air in when you open it?

I had a bike do this and it was the tank vacuuming down. It did it mostly on sustained climbing or high speed, and particularly so in cold weather. We modified the filler so it vented slightly. Aparrently this is not a legal mod in the US. Lucky I aint in the US.

Steve

[vindy500]

yeah seems to run sweet in prime, in fact today the only way to get it to run alright was in prime, so vacuum, what should i do about it?

[MSTRS]

yeah seems to run sweet in prime, in fact today the only way to get it to run alright was in prime, so vacuum, what should i do about it?

Fix it.
I don't know how tho...

[xwhatsit]

yeah seems to run sweet in prime, in fact today the only way to get it to run alright was in prime, so vacuum, what should i do about it?
Feckin' useless fancy-arse vacuum fuel taps.

Buy a bike with a proper fuel tap (i.e. On/Off or On/Off/Res) and don't be a dumbarse and forget to turn it off if your float valve leaks....

I suppose check that the vacuum hose isn't leaking at all, that the wee diaphragm is sealing all right.

[vindy500]

I suppose check that the vacuum hose isn't leaking at all, that the wee diaphragm is sealing all right.


How? :)

char

[xwhatsit]

I'd pull it to pieces and check it's whole and not perished but I'm not too bright about things like this :D

[vindy500]

ok just to confirm, on the petcock theres 2 hoses coming off it, one going through a fuel filter the other one not. is that the vacuum hose? or is the vacuum hose the one coming out of the tank on the otherside which goes to a T junction and i havent bothered to follow it any further?

[MSTRS]

The vacuum hose is the smaller diameter hose coming off the fuel tap. It goes to the inlet side of one of the carb bodies.

[sinfull]

i havent bothered to follow it any further?
So ummm do you want us to do it ?
Tank off , tap out , check no rust coming out of tank ! Follow vac and check it has no holes or splits !

[Grizzo]

ok just to confirm, on the petcock theres 2 hoses coming off it, one going through a fuel filter the other one not. is that the vacuum hose? or is the vacuum hose the one coming out of the tank on the otherside which goes to a T junction and i havent bothered to follow it any further?
So take it down a dark alley and kick the shit out of it.

[vindy500]

The vacuum hose is the smaller diameter hose coming off the fuel tap. It goes to the inlet side of one of the carb bodies.

thats what i wanted to know :)

[vindy500]

took it apart today, vacuum diaphragm isnt sealed on one side but looks liek it would be sealed once the tap is screwed together.. would that make any dif? still goes in and out if you suck it. hose seems sweet. replaced the plugs when i was in there and it seems to run a bit nicer now. still did its whole running out of fuel to me today on the motorway though afterwards. at sustained high revs at about 140.(by motorway i mean private road) so its obviously not running perfect. oh and i replaced the o ring which had perished a bit in the fuel switch and put a new fuel filter in

[MSTRS]

OK...you're on the right track here. That diaphragm sounds like it's still not right. Or the whole tap is dodgy. Once you are sure it is operating properly, if the running out at revs problem persists you may need to check/adjust your carby float levels...that sort of thing. Leave them alone for the moment tho.

[vindy500]

alright, how to establish if the taps ok? the only hing i can think of is replacing it but i dont really have a spare handy :)

[MSTRS]

First check whether the diaphragm is a part. Sometimes with that sort of thing, all you can buy new is the whole thing.
If diaphragm is available, get a complete tap from a wrecker. Strip it completely and rebuild.
That way, you still have a spare tap that sort of works and, in theory, a perfect tap.

[vindy500]

today we stripped down the carbs, one of the slides was stuck, and a needle was loose. we fixed them and cleaned all the jets, now the bike doesn't die at high revs but it still wont accelerate much, cant get it above 120ish, and it still goes noisy when you accelerate at higher speeds, carb balance? valve clearance? fuel tap?

[rok-the-boat]

Clean the carbs, fuel lines, and tank. Make sure there is a filter. Set the float heights. If it's fuel related that should do it.

[Jantar]

The rubber used in the diaphrams of earlier model Suzukis was not compatible with our new fuels. I would suspect that the diaphram is perished and not opening all the way. You could replace the diaphram, but the same problem will re-occur in a few months. The best solution is to replace the entire fuel tap with either a more modern one, or (cheaper) simply leave the bike on prime and add a simple on/off fuel cock in the fuel line. The cheaper solution will leave you without a reserve position position.

[vindy500]

where would i get a more modern one from? can you get aftermarket ones? im not overly keen on having an on off switch, i can see that being a haslle when i forget to switch it etc