petrol smell after shutdown

[steve.n]

I have read numerous threads regarding this but mine seems to be a little different. I think!?

Smell is only from around the engine bay, no evidence of any leaks, nothing in the V or around the overflow, nothing around the carb bodies, while running or not.

Fuel pump is shut off, fuel filter run empty and the car allowed to stall, smell still present.

Seems OK when running but maybe this is just the fan blowing away any fumes.

All hoses checked ok

Any suggestions?

[Lingen]

Steve. You seem to have checked all the usual places, but it may still be a carburettor leak. Have you checked the "O" rings in the bottom of the float chambers? Even if you let them run dry, it will take some time for the leak to evaporate enough to stop the smell. Also, it might be worth checking the short section of rubber fuel hose where the nylon pipe from the back of the car connects to the piece that runs up to the filter. It is low down near the point where the front bulkhead joins the passenger floor pan.
Mike,

[steve.n]

Thanks Mike, all hoses are fairly new and have been checked, also the bottom of the float chambers feel dry.
I did wonder if there would be residual fuel in the float bowls, i suppose a carb rebuild is on the cards.
Steve.

[StagJonno]

For sure, check for leaks, but I'm guessing there'll always be a bit of fuel in the lines which, with residual heat from the engine will cause evaporation to produce perfume. It's a question of how much is acceptable, which is probably subjective.

Jonno

[Wisey]

It might be worth checking the operation of the vent valves on the side of the carbs. At idle, or stopped, the float chambers should vent out through the vent pipes down the front of the engine to floor level. When the throttle opens, this vent route should shut. If your vent valves are blocked, venting fuel vapour would get forced into the inlet manifold and may cause the fuel smell. Not sure how much fuel would be left in the float chambers after running the "dry" as described above....
Steve

[markmark2]

Is there a way to check the operation of the vent valves? I too have just started to get a fuel smell which I havnt had before. Cheers M

[Lingen]

Mark.
It is easy to check them but difficult to explain where they are to do so!
Each one is at the bottom of the tube that has the rubber elbow on it, then the black plastic breather pipe that goes to the back of the air filter box..If you look at the linkage at the opposite end of that tube, you will see a small plunger poking out. There is a small bell crank that pivots at the moment that the throttle starts to open, and moves away from the end of the plunger. This operates the two way shuttle valve hidden inside. It is (weakly) spring loaded, and should pop out as you open the throttle. You should be able to push it in and out with a small screwdriver. If it is stuck, then remove the rubber elbow, and squirt some WD40 down the tube. Then you need to grip the end of the plunger and pull it in and out till it frees off. You could also put a thin rod down the tube and push the plunger out, but do this carefully or you may damage the small coil spring down there in the process.
Mike.

[markmark2]

Thanks again Mike, a hive of information! I will check this. Cheers M

[markmark2]

Hi Mike, I found what you refer to. However, the passenger side cam/arm that pushes the valve back in when there is no throttle is completely missing the valve so the valve is in the 'out' position all the time. I don't think that should be like that. I assume this would mean it isn't venting on one side? Thanks again. Mark

[steve.n]

Lots to think about. i did find what i think is being referred to and one was stuck, freed up with a squirt of WD40 but i will check further.
Steve.

[steve.n]

Rechecked and found the lever was sticking again, WD40 seems to have freed up again but i will check when its cold, however freeing a sticking lever may not have freed up the valve, sprayed WD40 down the breather tubes as suggested, fully warmed up the engine then shut down, 5 minutes later and smell seems to have gone, YIPPEE! Thanks folks.
Steve.

[Kithmo]

Now it stinks of WD40

[steve.n]

Read a bit of trivia about alternative uses for WD40, it included cleaning silverware, car windows (stops icing) toilet bowls, sinks, shoes and removing chewing gum from hair.

Mmmm!

[Stokiestag]

Having a similar sort of problem,after stopping the car is reluctant to pull away cleanly until you get on a straight flat road then seems to clear itself but when you go upbank starts to miss again.Thought I'd check out those vent valves and ! there is none on view ?. Checked a spare set of carbs in the garage and they have them and seem to move/work as they should .Any ideas,smells petrolly