Carbs I rebuilt leak gas, help?

[LAWN BOY]

I have 2 carburetors that I’ve rebuilt that leak gas. They’re both Walbro on my Homelite EZ AO and Ryan 263 weed trimmer. It’s not the fuel line, the carb itself leaks after I rebuild them. Could anyone please tell me what I’m doing wrong?

 

[Powerstroke Cowboy]

What part of the carb is the gas leaking from?

The more information you can give the better.

 

[Shane¹]

Where is the gas leaking? Post up some pictures

 

[Coupe]

May be your needle valve is leaking.
Did you pressure test them before fitting them back on.
I pressure test mine every time .
If you are going to repair your own carbs may pay to
buy a mityvac MV8500. For the price it may save you a
lot of headaches.

 

[Gullet]

Gasket or fuel line if leaking gas.

 

[Steelie90]

I just had a Walbro HD-10 doing that after I put a kit in, but only when tank built pressure from heat. Very small leak. Put 10psi on carb and place carb in a container of fuel and look where the bubbles are coming from.

If leaking fuel into cylinder, your needle is leaking.

Also make sure the covers are not warped from over tightening.

 

[pbillyi69]

make sure when you do the pressure test to get a little bit of mix into it so that the needle can seat propperly. sometimes the needle wont make a tight seal when its dry

 

[LAWN BOY]

I do not pressure test carbs, I really should tho invest in the setup. I’m unsure as to where exactly gas is leaking from. Even if it’s just attempting to start a puddle forms as shown.

 

[Stump Shot]

I do not pressure test carbs, I really should tho invest in the setup. I’m unsure as to where exactly gas is leaking from. Even if it’s just attempting to start a puddle forms as shown.

You should learn and avoid all the unnecessary work involved after rebuilding a carburetor. About seven pound or .5 bar should be enough. If you continue to have difficulty pinpointing the source, dunk it in a clear jar/glass of water and look for where the air bubbles are coming from.
One thing that helps avoiding leaking from the covers is to pre-soak the gaskets in fuel mix for a minute before installing. That allows them to swell and seal right away, some small gasket leaks will otherwise swell and seal when fuel mix gets to them.
This should be all you need to get started testing carburetors.
https://www.hlsproparts.com/product-p/h70100.htm

 

[hacskaroly]

I do not pressure test carbs, I really should tho invest in the setup.

You can get some fairly inexpensive setups for testing carbs. I got one of these small testers just for working on carbs. It is small and easy to use one-handed if you have to hold onto the carb too.

Carburetor Leak Detector (Amazon)

I also got a MityVac type setup for testing pressure on cylinders. When working on a carb, I usually get a little fuel on the gaskets, diaphragm and needle to reduce the chance of leaks from dry fitting. Also like said before, don't over-crank the screws in and make sure there isn't any debris or old gasket stuck to the carb body or plates, that can also cause issues with leaking.

Edit: What @Stump Shot said

 

[LAWN BOY]

Ok, thanks for the information. I did not know about soaking gaskets, etc… in fuel mix a bit before installing, I’ll have to do that from now on. Are these carb pressure gages an appropriate candidate in the tool world to get the cheaper one of? The reviews seem good for this $23 one…

Carburetor Leak Test Detector Pressure Gauge for Walbro 57-21 Stens 705-020 | eBay

705-020 Stens. 57-21 Walbro. Used to test walbro and other 2-cycle carburetors for leaks. 1PC Carburetor pressure gauge.

www.ebay.com

 

[hacskaroly]

The reviews seem good for this $23 one

I made sure to read the reviews of the one I got, found several reviews for one said that the gauge was faulty and would never settle on zero or would act sporadically. Cheapest is not always the best...but sometimes its all one can afford at the moment.

 

[LAWN BOY]

I made sure to read the reviews of the one I got, found several reviews for one said that the gauge was faulty and would never settle on zero or would act sporadically. Cheapest is not always the best...but sometimes its all one can afford at the moment.

I know. I pick and choose what tools I spend lots of money on and which ones I go the cheap route with.

 

[pbillyi69]

i have found that if a tool i need is going to be used more than once or twice its worth it to buy a good one. if i only need a tool once i will go to a hawk shop first and see what they have. sometimes you can get a good used tool for less than a cheap new one.
edit to correct spelling

 

[pbillyi69]

a mighty vac is around a hundred buck and can be used for carbs, cylinders, and the brakes on your car. when you look at its multi uses it becomes a great value for 100

 

[Stump Shot]

Ok, thanks for the information. I did not know about soaking gaskets, etc… in fuel mix a bit before installing, I’ll have to do that from now on. Are these carb pressure gages an appropriate candidate in the tool world to get the cheaper one of? The reviews seem good for this $23 one…

Carburetor Leak Test Detector Pressure Gauge for Walbro 57-21 Stens 705-020 | eBay

705-020 Stens. 57-21 Walbro. Used to test walbro and other 2-cycle carburetors for leaks. 1PC Carburetor pressure gauge.

www.ebay.com

Yes, that will work, I have one from Zama that is very similar.
Once you get to using it remember that a slight leak that takes over a minute to drain down, is not a failure in one of these carbs, just the leaks that drain down right away. Usually after a rebuild that would indicate a gasket leak that most likely heal itself after some mix hits it and it can finish swelling. It's also not enough to cause a run issue or dump fuel in the carb box.
There's some good information in repair manuals for more details of the particular carburetor that you are working on. After a while it will become old hat for you.