Surprise Fuel Leak!

l008com

l008com

Well-Known Member
Got a freebie "doesn't run" mower thats been siting in my basement for 2 years. Today was the day to start working on it (i make videos of the repairs)

So after doing basic checks, everything seems good, so I put some gas in it and before I can even try to start it up, gas starts gushing out.


It looks like its leaking in multiple places. It looks like its slowly leaking where the fuel line connects to the tank. As long as the tank itself isn't cracked, that should be an easy fix. I can just replace the fuel line, I have tons of it.

Whats going on at the carb is another story (maybe?)
Note that after taking that video of it gushing fuel, I did try to start it, and I was successful! I got it running and it ran for half an hour or so. Leaking fuel the whole time. It was squirting out of the primer bulb.

I ran it until it ran out of gas and now its sitting in my driveway while all the spilled fuel evaporates.

Clearly I need to replace the fuel line, but is this also a carb issue too? What would cause fuel to squirt out of a primer bulb? Its like theres back pressure in the fuel line, and yet it was sucking in all the fuel it needed just fine.

Or is this somehow just another less-common symptom of a dirty carb? Since, you know, the problem is always a dirty carb!
 
Ran it for half an hour with a known fuel leak? I'm surprised it did not burst into flames.

Replace the fuel line and primer. Next, replace the carburetor unless you know how to properly rebuild it with more than a spray can.
 
Float needle is stuck open. Time to clean and rebuild the carb with a knew float needle and seat. Here’s a procedure I taught my students.

Needle and seat replacement.

Remove the carb, and then remove the float bowl. Check the float bowl jet (which is the bowl screw) and make sure the jets both horizontal and vertical are clean and open. Tip the carb upside down and remove the float pin and float with needle attached. Look in the float needle passage and you should see the red float seat at the bottom of the passage. This is where a #5 crotchet hook would come in handy as you need to remove this seat. If you have no hook, but compressed air, you can blow through the fuel inlet and try to pop the seat out. Put your thumb over the passage to prevent the seat from flying who knows where. No air or hook try bending a stiff paper clip to dig the seat out.

I would either give the carb a good 24 hour soaking or have it ultrasonically cleaned at this time.

With the seat out clean the passage way with carb cleaner. Now you must find a drill bit slightly smaller than the passage way, to be used to press in the new seat. Apply a very, very small amount of a very light lube to the new seat. 3-1 oil or lighter, to help seat it better. Carefully insert the new seat in the passage way with the rings on the seat down toward the carb body. Slowly and carefully force the seat down with the back end of the drill bit. Once it is seated, check to see that it did not flip and the rings are up. Next check to make sure that the float does not have any liquid in it. If it does, replace. If everything looks correct, attach the new needle to the float and install with the float pin centered. It everything is correct, the float should seat level to the carb body, when looking at it upside down. If everything looks good reattach the float bowl, making sure that both the bowl gasket and the nut gasket seal properly. Reinstall on the engine and test unit. Remember to have patience and take your time. Good luck, but I don't think you'll need it.

PS: On the side of some Tecumseh carbs you will find a plastic cover. Under this cover will be an idle jet. Remove it and check to see that the jet is open both horizontally and vertically. You should be able to push the old float needle wire through the vertical opening.
 
Ok in a few days I guess I'll take it all apart, get the carb on my workbench, and then get to work. It smelled BAD even after being outside for a few hours, so I'm going to leave it outside (under a roof) for a few days before I bring it inside to work on it. But yeah a questionable fuel line plus questionable float seal plus... who knows what with the primer, that does all add up and make sense. Since when do mowers even need primers these days though? I'd rather just go without but I'll have to see how it all goes together and if thats even possible.

@Rivets regarding your PS, do mower carbs usually have an idle jet? I thought they only had a high flow jet because they only run at one RPM, which is Max RPM? I cleaned out the idle jet of a snowblower carb last winter by soaking it in cleaner for a few days and then blasting it clean. It was like night and day after that. The thing ran like it was brand new.
 
Update time!

I took the carb off tonight. As soon as I unbolted the carb, it was time to disconnect the fuel line. But no need, the fuel line basically crumbled in my hands!
So I don't know if that was 100% of the leaking. The needle seal looked ok when I got my eyes on it, but it kind of disintegrated while removing it. The bowl seal also kind of disintegrated as I removed it.

So everything that is solid metal or plastic looked fine, I just need to replace the soft parts and I think I'm good. I still have tons of fuel line left. But where can I get a bowl seal and needle valve seal? Are they all the same size or do I need to measure this carb? I need to see if I can look up the model number on the engine, I'm not sure yet if I have that or not. But I was kinda of expecting lowes or ace type stores to sell little rebuild kits but I'm not seeing anything like that.

I think thats it though. Once I replace those two seals and the fuel line, and sharpen the blade, I think this machine will run like new.

Edit: Ok I ended up just getting the individual part numbers from the engine serial number and then finding them on ebay. I should have this thing running real soon!
 
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Hello John,

Modern fuels regardless of station brand tend to soften and age or dry out fuel lines. Heat and environmental exposure tend to make it happen faster. Fuel line replacement should be considered every few years because they fail from the inside and not the outside where you can see it.

I use eBay quite often for parts, but I buy the complete carburetor rebuild kits or a clone carburetor. I have never been a fan of Amazon, but that is my choice.

For odd machine specific parts, I use Parts Tree or Jack's small engine

Don't throw anything (new or old) away until you are sure the problems are resolved. It can also be a blessing to have the extra new parts around later.
 
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