Z425 Fuel Leak

[depawl52]

So my 12 (+/-) year old Z425 began flooding when the choke was on, and leaking fuel which I eventually figured out was coming from the muffler. The next day the problem somehow resolved itself.
Seems to be running OK ever since.
Anyone have any ideas as to what the issue might have been?
Thanks.

 

[Auto Doc's]

Sounds like some sediment got in the float bowl and prevented the needle from seating and shutting off the fuel. A good carb disassembly and cleaning is likely needed.

I install a manual fuel shutoff valve in the fuel line of all my equipment, then run them dry when shutting down.

 

[depawl52]

Thank you Auto Doc. I kind of figured it was a carburetor problem. I've been watching youtube videos on carb disassembly/cleaning, and although I haven't found one for this particular model, all of the Z's seem to be pretty similar.
As as side note, it appears that new carburetors on Amazon are only around $50 so I may just go that route.
Thanks again.

 

[depawl52]

Update: After running fine for 2 months (and mowing a lot of lawn) the same problem resurfaced. I got up this morning and noticed a strong smell of gas in the garage, and a small puddle of gas under the mower. It was running fine with no leaks when I put it away night before last. If the problem truly is a stuck needle valve as Auto Doc suggested above, would it start to leak while the tractor is just sitting/not running?

 

[slomo]

I got up this morning and noticed a strong smell of gas in the garage

Do you have any gas pilot lights going in your garage? If so I would get the mower fixed asap.

You have a 12 year old mower. Time for maintenance.

1.Full carb clean or replace
2.New fuel line from tank to carb
3.New fuel filter and shutoff valve
4.Fuel tank super flush
5.Final hose pull off AT carb inlet. Verify solid flow AT carb.

Now back to your issue. Carb needle and seat cleaning or with 12 years on her, replace both parts.

If you can smell gas vapors in the garage, you need to pull the oil stick and smell for fuel. Most likely the oil sump has been compromised several times with gasoline. Meaning your oil is not oil anymore. Get the carb fixed asap and do a couple oil dumps.

 

[slomo]

If the problem truly is a stuck needle valve as Auto Doc suggested above, would it start to leak while the tractor is just sitting/not running?

Yes it could leak at anytime. They work just like a toilet flush valve does.

 

[depawl52]

Thanks for the replies. A new carb has been ordered.
Just wondering how to go about a "fuel tank super flush"?
Also, I pulled the dipstick and noticed a very faint odor, wasn't sure if it was gasoline or just the smell of oil, but I will most likely
change the oil just be be sure. How would one go about disposing (i.e. - recycling) oil that has potentially been
contaminated with gasoline? I normally take my used oil to my local Auto Zone store.
Thanks again for the replies and assistance.

 

[slomo]

Just wondering how to go about a "fuel tank super flush"?

Clean the tank like a new one.

Also, I pulled the dipstick and noticed a very faint odor, wasn't sure if it was gasoline or just the smell of oil, but I will most likely
change the oil just be be sure.

Fix the carb leaking issue first then do a couple oil changes. As in mow once, dump the oil and mow again. Dump the oil and smell the stick along the way. Confirming no smell of fuel in the oil. Add some fresh oil and mow normally. You can get a gallon of SAE 30w at wallys mart for 13 bucks.

How would one go about disposing (i.e. - recycling) oil that has potentially been
contaminated with gasoline?

I take mine and mix with Diesel 50/50. 100+ year old farmer's trick. Break out the airless sprayer and spray the wooden stockade fence. Trailer wooden flooring the same.

 

[depawl52]

Update: So after installing a new carburetor and fuel pump, I find that this Z425 will only start using starter fluid (or carb cleaner). I watched a couple Youtube videos and thought I had done everything correctly, including the choke and throttle linkages (which I had taken photos of prior to disassembly).
Any ideas as to what's going onm?
One question I have, is that it appears that it's not possible to check for proper functioning of the throttle and choke linkage when the engine is not running? I've done some research on this and is it true that this is actually controlled by the gouvernour, so they only operate when the engine is running? If so, how would one know if these 2 linkages are functioning properly (Since (at least the choke) is obviously not in this case.
Also, I noted that at idle the engine runs at a higher rpm than it did before, and I can verify that the throttle is bottomed out, and it appears that this carb has no jets that are adjustable?

Thanks in advance.

 

[slomo]

Update: So after installing a new carburetor and fuel pump, I find that this Z425 will only start using starter fluid (or carb cleaner).

What do you think, the engine wants? If you spray go-go juice and she runs for a bit, then dies.........

Did you clean the fuel tank, like a new one, as suggested previously? Didn't see anything about cleaning anything. Probably needs new fuel line from tank to carb. Fuel lines "can" deteriorate internally so you can't see the blockage.

Did you test this new fuel pump?

All new parts, require, testing. Getting your credit card out and buying all the parts, that most people hear about (spark plugs and filters) is not the way to get your mower running. Heck you just proved it.

You need to test what you have first. Most of the time these tossed out parts are good as most don't know how they work.

Far as the choke and throttle goes, probably need to download the engine manual and read it.