A forum for owners of Yamaha TTR250 trail and enduro bikes!

rogpreston · Member

Fuelling Problems.

Cubber · Super Guru

Try looking at the tank filler cap - is the one way valve working OK?
When it next happens try unscrewing the tank cap and if you hear air intake then air is not replacing the used fuel!
Other than that - I don't know.
Martyn

TTRfan · Super Guru

I reckon Martyn has nailed the problem. Had exactly the same thing on a blue TTR - one-way valve clogged up not allowing air into the tank to replace the fuel being used.

Let us know how you get on please wink

Brian

rogpreston · Member

Thanks but the breathing system is ok. cheers rog p,

TTRfan · Super Guru

Shame - that would have been an easy fix!

Next thing to check is that the petrol runs freely out of the tap if you haven't already done that. Get a petrol proof container, take off the fuel line and run some petrol into the container to see if it flows freely.

If that's OK then the next step is not so easy. The filter above the float needle could be blocked. I have identified it in the pic below:

carb fiche showing filter.jpg

To get at it you need to remove the carb, float bowl and parts 11, 12 and 16.

The float retaining pin 12 can be a pain to get out and you need to be careful not to break either of its support posts. It will only come out one way - see the arrow on the post.

It may be possible to check if the filter is clear by undoing the drain screw at the bottom of the float bowl and seeing if petrol flows freely when the tap is turned on - not forgetting to hook up the fuel line first! If it does then I don't think your problem is necessarily a fuelling one confuse

If fuel doesn't flow freely you probably need to check the filter cry

Brian

rogpreston · Member

Ok thanks for the info Brian. Prior to your e mail I had the carb off again and found the said filter hiding in the fuel valve assembly.. this is not shown in the workshop manuel !! any way this filter was not too bad but had enough gunge in to foul up the flow at prolonged high revs so cleaned it out and its now ok. I will need a newfuel valve assembly as mine is also leaking past and flooding the carb but the fuel starvation problem is solved Thanks. Do you know where I can obtain a new fuel valve assembly? cheers for now rog p.