gas fumes

[jdeboer]

First of all, Don, thanks for giving all this great advice last year, with the help of my carburator and oil pressure problems!

At the moment my engine runs great, however i do smell gas fumes after i use my engine. I cannot find any leaks however (even not around carb, which was the problem child last year and has been replaced).
My fuel pump has never been replaced, and I'm wondering if tiny cracks in the pump can cause these fumes (or would tiny cracks even prevent the engine running smoothly?)

If so, should I order the repair kit to fix this or can you think of any other possibilities?

Thanks!

Jolanda
ericson 29, berkeley CA

[rgoff]

Try wiping a paper towel over everything you can think of that might leak. Any fluid would show up on it.

[jhwelch]

When I get gas fumes it is because the needle valve in the carb.
is not fully seating and preventing a slow siphon effect from
happening. How do I know? I close the valve from the fuel
tank and that stops the problem. Try that and if your fumes
stop then you can take your carb. apart and clean around the
valve seat with a pointed dowel and also look for small bits of
grit that may be preventing full closure.

-jonathan

[Don Moyer]

Jolanda,

It's quite likely that your mechanical fuel pump is the culprit, particularly if it's the original pump. It is usually possible to pick up a little gasoline on your finger tip if you feel completely around the pump, but not always. I doubt that the pump housing is cracked or you would see more evidence of fuel. You may be able to tighten the screwdriver slotted retaining bolts around the diaphragm housing. They sometime become loose.

A more serious consideration would be if the diaphragm is actually leaking. If this were the case, you would almost assuredly see some fuel dripping off the bottom housing in the area where the priming lever attaches and pivots. You would also smell fuel in the oil, as well as on the dip stick.

If these suggestions all fail to reveal any specific cause of the fumes, a rebuild of the pump is probably warranted.

Don

[Don Moyer]

Good for you Jonathan! In fact, along with closing the fuel shut off valve, one could remove the flame arrestor housing and physically inspect the bottom of the intake throat of the carburetor for the presence of raw fuel, both with the fuel valve open and then with it closed.

Don

[jdeboer]

Thanks everyone!

I have removed the flame arrestor and inspected the intake throat of the carb, but bone dry so far (both with fuel valve open and closed). I guess that takes me to the fuel pump.

Jolanda

[Don Moyer]

Jolanda,

Just to be sure, I would check the carburetor after running the engine for a while, and (more importantly) during a time that you're actually smelling fumes.

Don