I have a MTD honda lawn mower (Model # 12AV55DQ713) with GCV190 engine. It won't start. I first identified the problem in fuel flow. The fuel line is clogged somewhere by taking off the
bottom bolt on the carburetor, no gasoline is flowing out. I can start the engine with starter fluid.
Since the fuel line to the carburetor got stuck I couldn't take off the fuel line from the carburetor, I bought new carburetor and fuel line to replace them both at the same time. After installing everything back with the new carb and fuel line, I checked that gas is flowing out this time from the bottom of the carburetor. This means at least there is a correct flow of gas to the carburetor from the gas tank after the initial repair.
I was expecting the engine to work, but when I tried to start the engine, again I found only the starter fluid works. The engine won't start by itself. I am now out of ideas what's causing the engine not starting.
Additional facts and questions,
1) the carburetor gaskets are out of shape, 2 of them are slightly teared when taking them from old carb to the new carb. They are just teared. How serious is this?
2) I checked the spark plugs, it looks okay, also I thought if I can start the engine with starter fluid, the spark plug in theory should be okay?
3) the carb choke closes but not like a perpendicular (complete?) close in the carb, is this normal? It closes with a slight slant.
Did you buy a genuine Honda carb or did you play lucky dip with amazon / ebay ?
In order to start the choke must be able to close tight against the sides of the carb
Most times it will not be square across the body, but it must be tight against the body .
If you have a manual choke it is adjustable
IF it s ab auto choke then it usually requires replacing the auto choke mechanism
Some time you can ben the link rod, enough some times not .
If you can start if on starting fluid the choke is a moot point it should keep running if everything else is in good shape. Bad carb mounting gaskets can allow it to suck air by the bad gaskets and not through the carb and it might not run if they are bad enough. Sounds like you have a fuel delivery problem.
Yes. I assume from the way you are talking it keeps running. Then I would suspect an air leak around the carb mounting gaskets. Get it started and spray something around the carb. and the intake and the engine and intake. If it changes the way it runs you have an air leak.
Oh, sorry I wasn't clear in my description, the engine stops running very quickly when the starter fluid is used up. It does not keep running. The engine won't start without starter fluid.
Rule of thumb
If it starts on spray down the the carb throat and can be kept running for a minute or so with repeat SHORT shots down the carb then you have a fuel supply problem which includes a big air leak.
The back of the carb has a hole in the flange which is the air vent to the float bowl
his has to line up with a hole in the gasket so air can get sucked up the curved slot.
No air in the float chamber = no fuel out
Take the float bowl off and turn the petrol on
Check that the float drops & you get a good flow which will sop when you lift the float but stop before the float touches the body.
A genuine Honda carb should have a tap on the side
Occasionally they do block off
Some times people forget to turn them on
On the other side of the carb there are 2 or 3 small holes which the front gasket is cut to avoid blocking them off.
One of them is the pilot air supply and if it is blocked then the carb just won;t pass fuel as this air is needed to atomise the fuel in the venturi tube as well .
Thanks, this is really helpful. I’m trying to follow what you described using the old carb I took off. i think I might have a gasket problem causing fuel delivery failure. Before I get a new set of gaskets, will the tear in the gaskets cause problem or maybe it’s mainly a problem I didn’t line up the openings correctly. I’ll check tomorrow.
If I had $ for every not running properly honda powered mower / pump / generator / pressure washer that came through the gate with the gaskets & spacers all messed up you would not be reading this.
I would be sitting on the beach with cold drink in my hand every day having long since retired.
The usual culprit for blocking off the vent hole is globs of silicon because the owner was too cheap to spend $ 5 on a gasket set.
Then thee is the thick spacer which for some reason every second person wants to put behind the carb not in front where it belongs .
But you have to start by checking the flow out of the needle valve.
People changing from B & S engines just about always forget to turn the fuel tap on the right hand side of the carb on.
I have even seen them fitted backwards or with the choke & throttle hooked up crossed over or the choke backwards
solved! It must be a gasket/fuel delivery problem, I reinstalled all the gasket then it worked great. Also replaced spark plug, air filter, sharpened the blade, and put in new Honda Oem 10-30w engine oil, this machine runs great.
You stated "solved" but not what the problem you found was. Was a gasket not on correctly or what? Enlighten us?
I've worked so hundreds of horizontal Honda GX series and found your symptoms did not make sense. Very much doubt that anything was wrong with the carb.
