Lawn Boy Owner Check-In --- Read This First!

[Landngroove]

Hello Everyone: I have a 1986 Lawn Boy Model 7035. I puchased this new back then, and have used it every season since. You can't beat the Lawn Boy 2 cycle engine for durability. Great Machines ! :thumbsup:

 

[v0lten]

Hey Lawnboy owners!

My names Eric. I was given a Lawnboy Silver Series 4-cycle 4.5HP lawnmower by my father-in-law last year when we bought a house. It ran really good until the end of the season and I would sometimes have to pull to start, then push the primer a few times before it died and then play with the choke so it ran at a really high rpm for a bit, then it would stay fine. Now this season, it ran perfect for a few mows and now is back to the original problem, but worse, I cant get it to stay running whatsoever.

I've never taken apart a mower motor before but I'm pretty good with my hands and like getting things done and learning things. So I began taking apart everything on the Tecumseh LEV 100 motor. The air filter was a bit dirty and maybe a little bit of oil was in the air filter too, but, I don't think that was the problem. After taking off the carburetor and taking off the linkages, I removed the float bowl. After removing it, this little needle (I think called the inlet needle) fell out before I could see how it was seated. Other than that falling out, I was able to clean everything up a bit and put it back together properly (Everything was actually pretty clean, so idk what the problem is still). I put the needle in the hole where it goes and put everything back together. Still the same problem, it just seemed like it wasn't getting any fuel. I figured it probably had to do with me not putting the inlet needle back in the right place or the pin that is attached to it not back in the right place. So I took the pin and put it around the pin that holds the float in place, and it actually looked like it belonged there, but still, same problem with the motor not staying running. The motor does turn a few times like its getting the tiniest bit of fuel but not a good enough flow to stay running. Even pushing the primer button doesnt keep it going.

Perhaps the inlet needle and pin isnt even the problem, but I want to make sure I at least put it in the right place, here is a picture. The blue line is the pin that is going around the float pin.

Here is a diagram on Partstree of my model carburetor.

I've also noticed that when I push the primer bulb, I dont hear the liquid "squish" of gas like I have felt in my string trimmer and other lawnmowers. The bulb itself seems like its in good shape though and doesnt seem to a problem. Is it normal to not hear or feel the "squish"?

I've also tried replacing the spark plug.

Any other ideas, questions, comments, ANYTHING is greatly appreciated! Im so glad I found a forum like this that will probably be able to help me. I love this lawnmower and feel like I owe it a chance before I give up on it.

Another question on a side note (lol): I always use 93 octane in my power equipment, instead of 87, is there any real benefit to doing so, or am I just wasting my money?

Thanks again!

 

[Landngroove]

Hello Eric; If you suspect the carburetor is the problem with your machine, you should remove it again, dis-assemble it, and soak it in a carburetor solvent. Also get a rebuild kit. You can replace the needle and seat, and gaskets. After soaking the carb, blow it out with compressed air, and check all orifices to make sure there is not the tiniest blockage. Take a fine piece of wire, and insert in these orifices to make sure they are clear. It sounds like you have a Tecumseh carb, so when putting the needle back in, make sure the long leg of the retaining clip, which holds the needle to the float, points toward the air intake of carb. The seat goes in with the grooved side into the carb body. Let us know how you make out.

 

[dwblue00]

The clip for the needle is supposed to ride on the brass float. There is a brass tang that allows the float to move the needle up and down accordingly. Also while the carb is upside down (with the bowl off) make sure float is level. (or parallel with the carb body) To adjust slightly bend the tang that the clip attaches to. While its upside down and adjusted properly blow through the fuel inlet, You should not be able to blow through. That means that the seal is also good. Also the float bowls deepest point should be farthest from the floats pivot point. There is a very informative video on youtube on how to rebuild the carbs on the 4 strokers. I found it under carb rebuild on TVS120 engine. I rebuilt mine only costs about $10-$12. Do just as Landngroove says and what I told ya and the engine will purr. Hope this helps ya. On the other note: 93 octane is really a waste of money. The manufactuers usually specify no lower that 87 octane. I really dont think you'll get a liquid squish when you primer the engine at least on these carbs.

 

[dwblue00]

The orange circle is the tang where that float clip slides on to.

 

[v0lten]

Well I took everything off, cleaned everything I could find at the time with a wire and sprayed a bunch of carb cleaner. I also hooked the inlet need back together correctly and the float is level. The best I could get was about 10 seconds of running while pushing the primer button ferociously to get it to stay running, but, even with that, it still died.

I did some more reading around and I learned a few things that I missed before. I didnt realize the brass bolt that attaches the float bowl is also the main jet, and I believe I missed the very tiny jet that is at the top of the threads. I also destroyed the washer that goes on that bolt from over-tightening. I also didnt realize the bowl is supposed to go back on in a certain direction (the dented end towards the pin holding the float so the float can have more room to drop). And last but not least, I have found a lot of people talk about welch plugs. I havent found any really good diagram to see what they are, are they the two round rusty looking things on the underside of the carb that you can see in my picture?

Someone said they had rusty welch plugs and replaced them and it fixed a similar problem to mine, but, that it was a tricky job and you can permanently damage the carburetor.

Any more ideas are very welcome, I just had to mow my overgrown lawn with my dads old push mower. Man I miss this lawnmower.

 

[Landngroove]

Sounds like a passageway/orifice for fuel is blocked. It could be dirt, or it could be a result of old fuel varnish, that needs to be dissolved. I have dealt with conditions like this before, and had to immerse disassembeld carb in solvent for a good 24 hours, and then blow out with compressed air.

 

[dwblue00]

I agree with Landngroove there must be some dirt somewhere plugging up the venturi or the brass bolt that holds the float bowl in. Get a old paperclip and a twist tie from a garbage bags box and clean every hole, orfice, and passageway. I had a 2 stroke that did the same thing your describing and it was dirt in the venturi. Carb cleaner isn't always enough to clean out all the dirt. If you didn't already get a rebuild kit. You'll get it running. With all of us on here, your in good hands.

 

[v0lten]

Thanks for all the advice, I plan on buying a few things I need and then attempting it all again. Ill keep everyone informed

Any other ideas in the meantime are still welcome

 

[v0lten]

Well good news!

I ordered a few new gaskets and a welch plug and started taking apart the carb again. This time making sure to clean every single orifice that I didnt know about last time. I also took off one of the two welch plugs (I took off the easier one of the two). Man, that was a good build-up of rust on the underside of that welch plug. I also took off the idler screw(I think thats what it is, and cleaned the tiny hole inside there. I installed the inlet needle the correct way and tested the seal by blowing into the fuel inlet to see if it leaks (it didnt). I installed the fuel bowl the correct way so that the float can dip down into the indented part of the bowl.

I basically did everything you guys told me to do plus a few things I learned in some other places, lol.

Once I started trying to get her going I was having dejavu. Same problem of just not starting at all. After about 20 pulls and lots of priming, I decided to mess with the choke screw and open it up a little. After a pull or two it started running very low rpm for a few seconds before it died. So, I opened it up a few more turns and Vroom Vroom on the first pull. I left her running for about 10 minutes and she sounded great!

Now my next project is to sharpen the blade and probably change the oil while Im under there. Cant wait to mow my lawn tomorrow!

Thanks again guys for helping me troubleshoot!!!!