I found an old Lawn Boy model 7035 in the back of an old shed in Virginia. I cleaned the carb and replaced the sheered flywheel key and now it runs Okay. The problem is the enormous amount of fuel that is pouring from the carb. I ended up replacing the needle valve assembly but that didn't help in the slightest. When it runs, all I have to do is open the fuel valve until it begins to leak, then I can close the valve completely and it will still start and run strongly. I'm all out of ideas on what the issue is so I hope one of you guys could give me some advice. Thanks.
Lawn boy 7035 Carb Issue
- Thread starter rowen211
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EngineMan
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Best way is......does it float....!
LEAKAGE WHILE STATIC
To tell where a static leak is occurring, remove the carburetor from the engine and remove the float bowl. Invert the carburetor with float and needle installed.
(with clear rubber hose) onto the carb fuel intake and blow,
Wet the needle and seat area with a small amount of gasoline. Needle/Seat minimum sealing pressure: 2 psi (14kPa)
POROSITY/EXTERNAL LEAK TEST
To test a carburetor for porosity or external leakage, invert the carburetor and submerge in a water bath. Hold the float with a finger to assure a seal between the needle and the seat. Pressurize the inlet needle to at least 8 psi (55 kPa). If there is porosity in the carburetor, bubbles will be present, erupting from the casting between the brass seat insert and the metal casting or from the fuel inlet fitting.
TEST RESULTS
If the pressure test reveals no bubbles from any component parts, check the float carefully by immersing it in warm water and watching for bubbles erupting from a seam. If all components test good, it is safe to assume that the original leakage problem was cased by dirt or debris.
SUCCESSFUL FIRST TIME REPAIR TIPS
To maintain a high level of success repairing leaking carburetors caused by dirt or debris, the first place to start is the fuel supply. The fuel tank should be drained completely and inspected for debris, dirt or scaling (if the tank material is metal). Clean or replace as indicated.
After confirming the integrity of the tank, remove all fuel lines and filters and replace with new. It is highly recommended that fuel filter be used in all but a few rare instances.
The only instance where the filter should not be used is when the fuel supply is gravity feed and the bottom of the fuel tank is less than 1 (2.5 cm) above the inlet fitting of the carburetor.
GO THE DISTANCE
It is important to go the distance and remove every 途emovable internal part and check for dirt or debris.
Many well intentioned repairs have returned to the shop due to dirt hiding in some small, difficult to
expose area of the carburetor.
If the inlet seat in the carburetor body is removable, do so, especially in the case of a chronic or repeated leak. Check in the repair manual for the proper procedures. Dirt and debris can hide behind the seat and, if disturbed, may cause leakage at any future time. If any dirt or debris is found, all (removable/replaceable) jets, air bleeds and pilot jets should be carefully checked, cleaned or replaced.
LEAKAGE WHILE STATIC
To tell where a static leak is occurring, remove the carburetor from the engine and remove the float bowl. Invert the carburetor with float and needle installed.
(with clear rubber hose) onto the carb fuel intake and blow,
Wet the needle and seat area with a small amount of gasoline. Needle/Seat minimum sealing pressure: 2 psi (14kPa)
POROSITY/EXTERNAL LEAK TEST
To test a carburetor for porosity or external leakage, invert the carburetor and submerge in a water bath. Hold the float with a finger to assure a seal between the needle and the seat. Pressurize the inlet needle to at least 8 psi (55 kPa). If there is porosity in the carburetor, bubbles will be present, erupting from the casting between the brass seat insert and the metal casting or from the fuel inlet fitting.
TEST RESULTS
If the pressure test reveals no bubbles from any component parts, check the float carefully by immersing it in warm water and watching for bubbles erupting from a seam. If all components test good, it is safe to assume that the original leakage problem was cased by dirt or debris.
SUCCESSFUL FIRST TIME REPAIR TIPS
To maintain a high level of success repairing leaking carburetors caused by dirt or debris, the first place to start is the fuel supply. The fuel tank should be drained completely and inspected for debris, dirt or scaling (if the tank material is metal). Clean or replace as indicated.
After confirming the integrity of the tank, remove all fuel lines and filters and replace with new. It is highly recommended that fuel filter be used in all but a few rare instances.
The only instance where the filter should not be used is when the fuel supply is gravity feed and the bottom of the fuel tank is less than 1 (2.5 cm) above the inlet fitting of the carburetor.
GO THE DISTANCE
It is important to go the distance and remove every 途emovable internal part and check for dirt or debris.
Many well intentioned repairs have returned to the shop due to dirt hiding in some small, difficult to
expose area of the carburetor.
If the inlet seat in the carburetor body is removable, do so, especially in the case of a chronic or repeated leak. Check in the repair manual for the proper procedures. Dirt and debris can hide behind the seat and, if disturbed, may cause leakage at any future time. If any dirt or debris is found, all (removable/replaceable) jets, air bleeds and pilot jets should be carefully checked, cleaned or replaced.
Last edited:
robinb66
Well-Known Member
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- Aug 18, 2012
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you could also try taking the float off and sticking it inwater holding it under if you see bubbles comeing up then its a pretty good sighn theres a leak in the float unless its a solid cork float instead of a metal or plastic hollow one
Good advice... from previous posters...
I do not think lawn boy uses a regular in line filter , my 10685 uses one in the tank itself.....
I guess that an approved filter is OK with the two stroke.
My 8237 uses a cork float, I'd like to clean it, but fear more harm than good..
Even a new , out of the box ,needle and seat can leak, one must seat them in, use a cue tip and a little steel wool..
A special dedicated tool would be nice to have.
Or a way of holding the needle and lapping it in, similar to how valves are done.
I do not think lawn boy uses a regular in line filter , my 10685 uses one in the tank itself.....
I guess that an approved filter is OK with the two stroke.
My 8237 uses a cork float, I'd like to clean it, but fear more harm than good..
Even a new , out of the box ,needle and seat can leak, one must seat them in, use a cue tip and a little steel wool..
A special dedicated tool would be nice to have.
Or a way of holding the needle and lapping it in, similar to how valves are done.
Don't like the idea of trying to lap in a float needle, you're asking for more trouble. I would take the carb off and open it up. Invert the carb with the float in place and if you don't have a pressure tester, blow into the fuel inlet. Iif you want you can attach at short piece of hose to blow into. You should not be able to open the needle by blowing with your mouth. If you have a pressure tester, the needle should break at 7-9 psi. This test will tell you if the needle is seating properly.