Fixes but engine won't start

F

farmstarter

Forum Newbie
I have a trimmer I pulled out after the winter. The engine is B&S 725 EXi.
It didn't start so I confirmed valve clearances, replaced the spark plug, and drained and refilled gas to proper levels.
It started twice but white smoke was billowing out. Internet said to wait as oil likely mixed with gas during repairs.
I gave it some time and tried pulling the cord again. It won't start.
I pumped out all the oil, drained the gas, and refilled both to proper levels.
The engine still won't turn. Sometimes there's a loud click right before the flywheel comes to a stop.

When I turn the flywheel manually it'll turn freely for a little over a revolution but then gum up a bit. If I apply enough force the flywheel will get through some resistance then turn freely for a little over a revolution and gum up again, etc.

Any ideas outside of going through the checklist again?
 
First thing I would do is pull the dipstick and check to see if it is over filled and smells like gas. If it does your float needle is not shutting off the fuel in the float bowl, allowing fuel to flow straight through the carb and into the cylinder and crankcase. If it does am right you will need to clean and rebuild the carb with a new float needle and seat.
 
take the spark plug out away from any ignition sources like a gas water heater etc., and try spinning it. See if fuel sprays out of the spark plug hole. If it does then that will confirm the carb is the problem. If fuel comes out the plug hole, the engine is hydro locking. Try to figure what part of the engine the noise comes from. It could be anything from the rope clinking back in to something in the crankcase. What kind of "trimmer" is this?
 
Sounds like he has a DR push or self-propelled type trimmer. I have one and it is a great trimmer for heavy jobs. It sucks that they do not have an oil drain plug on this engine design.

The resistance you are feeling when turning the flywheel is the compression of the engine.

The clicking is likely the starter head pawls.

Did you install the exact number new spark plug? These require a specific plug, not just one that fits.
 
Auto Doc's said:
Sounds like he has a DR push or self-propelled type trimmer. I have one and it is a great trimmer for heavy jobs. It sucks that they do not have an oil drain plug on this engine design.

The resistance you are feeling when turning the flywheel is the compression of the engine.

The clicking is likely the starter head pawls.

Did you install the exact number new spark plug? These require a specific plug, not just one that fits.
Click to expand...
These wheeled trimmers are horrible. Under powered, cumbersome, slow productivity, cannot adjust cut height. A good handheld trimmer will run circles around these turds.
 
I don't think we are talking about the same version of wheeled trimmer.

Nice, if they would give us the machine label information.
 
Is this resistance every 360 degrees or is it every 720 degrees? If I understand you correctly it is every 360 degrees then something blocking the piston from completing it cycle thru.

Need the engine's numbers to see if its an OHV or L head version. As if it is an OHV can also be a camshaft related issued.

With a L head normally you have compression only every 720 degrees. Now assumes the camshaft is rotating.

But with an OHV if the valves are not opening such as a dropped exhaust push rod then there is can compression every 360 degrees.

One other possible is a hyro locked piston/cylinder as you can't compress a liquid which raw gasoline is.
 
It's a DR trimmer/mower.
I could not find the same spark plug locally so just used one that fits. I'll have to investigate this further.
The resistance is more than every turn and likely just the compression after reading more on small engines.

I replaced the cartridge in the carburetor and now the engine pops at times when pulled. When I remove the air filter (after a pop) smoke swirls out of the inlet.
I guess the next step is to replace the float and needle?
 
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