Strong smell of petrol after running.

[Cryptorchid]

I have a stock '99 Carbon with 15k miles. It starts, runs and idles fine, but whenever I park it up there is a strong smell of petrol from around the dummy tank area when I get back. There is no sign of any leaks, but every time I start it up the fuel pump runs for a second even after a short-ish stop. After a couple of days of not running it sounds as if the float bowls are filling from empty.

It seems the fuel is evaporating. I usually have to park it outside for a couple of hours, so not to stink up the garage. Gas mileage is about 90 miles a tank, which doesn't seem excessively bad as I tend to do short trips a lot.

Has anyone got any ideas before I start pulling it apart unnecessarily?

Thanks in advance

 

[sdt354]

A leak check would be my first priority. And check down the carb throats too. It sounds like a leak and evaporation. 90 miles to the red res. light? Or including reserve? If that is with res. too much gas is being used.

 

[Traumahawk]

Look at the oil level in the sight glass, is the level "growing" in the sight glass?

 

[MaxMidnight]

What sort of distances have you run before you get the smell i.e. how hot would the motor be?
Does higher ambient temperatures make any difference?
Do you have both of the heat shields in place?
Have you taken the air-box off to ensure there ins't a weep from any of the fuel hoses?

 

[Redbone]

Possible carb float bowl drain screw needed to tightened up? As Max suggested if it's the original fuel hose it may need to be replaced, check the hose all the way to the tank. Leave your seat unbolted so you can remove it when stopping to see if you can find the source of the fuel smell.
A lot of us do not have our seats bolted down, as the flip seat latch does a fine job of securing the seat, my seat has been unbolted since 2007.

 

[Cryptorchid]

Thanks for all the ideas so far - gives me somewhere to start. The problem is present whenever the motor is warm, whether a five mile run to the shops or a 50 mile run to "check the v-boost still works". No sign of petrol in the fuel, no visible leaks without dismantling. The 90 mile range is from fill up to reserve, with about 25 miles on reserve (unfortunately not the 26 I was hoping for when I couldn't find a gas station :-( )

Looks like airbox off and a thorough leak check is first.

If anyone has any other ideas to add, they would be very welcome

 

[sdt354]

Not terrible mileage. It's capable of more though. My guess is a slow leak evaporating and giving off fumes. Careful. It will run without the air box, but not very well. I'd try to find a leak with a cold engine first.
Steve-o

 

[D-Max2012]

Same thing happened to me on the way to work one day.. Took off the airbox and found one of my overflow tubes leaking gas. Once I got to work, tapped on that carb with a rubber hammer handle to temporarily stop the leak so I could get home. I had to order a set of Yamaha Float Needles from Ebay. Once they came in, I removed the carbs, and swapped out all 4 needles. Tiny bits of Foreign Matter (FM), can get caught in between the hard rubber tips of the float needles and the tube seal. This is the reason why I coated my gas tank. To stop any rust build up and (FM) forming in my fuel system. The ethanol laced fuels over here in the US causes rust inside a steel tank, when phase separation occurs with ethanol, which draws in water from the atmosphere.

https://www.ebay.com/itm/4x-Carbure...ash=item4d3f6b00f7:g:SLsAAOSwQYZWvcr~&vxp=mtr

 

[1FK00]

That happened to my 03. It was the orings on the carb drain screws. They leaked just enough to get the carb bodies damp, but not enough to actually drip.