CV15S start=sputtering, backfire, surging. Fuel off=runs great then dies (obviousy)

[Fish]

Does the tractor have a model number tag?

 

[StarTech]

Plastic floats are adjustable; just got to know how. But as I said most likely you will need to replace the inlet seat and needle valve as it is a known problem that these Walbro carburetors have on the Command and Courage engines. Kit includes instructions on how to replace inlet and correct installed height for the float. OR you can get a copy of and read the instructions per TT-5237.

12 521 03-S KIT; INLET SEAT (GRAVITY) CMD
12 521 04-S KIT; INLET SEAT (PRESSURE) CMD

Kit retail between $44 and $46

 

[winmod21]

I'd Remove the float bowl off the carb, turn the fuel on, and lighlty push the float up until and/or see if it cuts off fuel flow. or how high it gets before the float shuts fuel off.

I realize this is an old thread, but I'm seeking some clarification on this test procedure. Do you the above ^ with the engine running or off? When Bertsmobile was kindly trying to explain the test procedure to me, the other day, I wasn't understanding what he meant by 'pressurizing the fuel line', and/or whether you do the above test ^ with the engine running, or not. I think he gave up trying to explain it to me after I asked him if you blow compressed air into the fuel line !

The CV15 is know to have needle/seat problems with the Walbro carburetor that is why a pressure test of the carburetor is done. IF it fails the pressure a new needle and seat are installed per the instructions included in the replacement kit. I have replaced several of these needle seats over the last 7 yrs. The pump fed carburetor are the worst leakers when compared to the gravity fed versions but both can leak.

Is the 'pressure test' the same thing as the above test-- where you remove the carb bowl and push up on the float? Is that a 'pressure test'? I'd like to do the test-- if I can understand how to do it. Thanks very much for any further explaining. ;-)

 

[winmod21]

I'd Remove the float bowl off the carb, turn the fuel on, and lighlty push the float up until and/or see if it cuts off fuel flow. or how high it gets before the float shuts fuel off.

I realize this is an old thread, but I'm seeking some clarification on this test procedure. Do you do the above ^ with the engine running or off? When Bertsmobile was kindly trying to explain the test procedure to me, the other day, I wasn't understanding what he meant by 'pressurizing the fuel line', and/or whether you do the above test ^ with the engine running, or not. I think he gave up trying to explain it to me after I asked him if you blow compressed air into the fuel line !

The CV15 is know to have needle/seat problems with the Walbro carburetor that is why a pressure test of the carburetor is done. IF it fails the pressure a new needle and seat are installed per the instructions included in the replacement kit. I have replaced several of these needle seats over the last 7 yrs. The pump fed carburetor are the worst leakers when compared to the gravity fed versions but both can leak.

Is the 'pressure test' the same thing as the above test-- where you remove the carb bowl and push up on the float? Is that a 'pressure test'? I'd like to do the test-- if I can understand how to do it. Thanks very much for any further explaining. ;-)

And would you Pro's also suggest purchasing a 'Leak-down Tester' and an 'Oil Pressure Tester' ?? Thanks.

 

[Rivets]

I’d only recommend making a purchase of a leak down tester if you plan on getting into the repair business. I’ve never used an oil pressure tester.

 

[StarTech]

How I pressure test a float carburetor is invert the carburetor; usually with fuel bowl off. Attach a pressure line to fuel inlet and pressurize 5-10 psi using my pressure/vac tester. With the system pressurized wait 30 minutes to see if the standing pressure drops.

As Leak down tester and an oil pressure tester those are usually reserved for shops. I think in the last year I have used my oil pressure tester twice before the current repair job but I will need it again once I replace the oil pump to verify that I resolved the oil pressure lost issue on the Kawasaki motor. Of all things they B/O the pressure regulator spring.

 

[VegetiveSteam]

I realize this is an old thread, but I'm seeking some clarification on this test procedure. Do you do the above ^ with the engine running or off? When Bertsmobile was kindly trying to explain the test procedure to me, the other day, I wasn't understanding what he meant by 'pressurizing the fuel line', and/or whether you do the above test ^ with the engine running, or not. I think he gave up trying to explain it to me after I asked him if you blow compressed air into the fuel line !

Is the 'pressure test' the same thing as the above test-- where you remove the carb bowl and push up on the float? Is that a 'pressure test'? I'd like to do the test-- if I can understand how to do it. Thanks very much for any further explaining. ;-)

And would you Pro's also suggest purchasing a 'Leak-down Tester' and an 'Oil Pressure Tester' ?? Thanks.

Save yourself some time and inevitable injury and get it to a qualified service facility.

 

[bertsmobile1]

This is why we discourage people tacking a "me to' on the bottom of an old thread.
It just confuses every one
I was fairly sure I had fully answered your questions
but please have a little think
1) engine will not run with the bowl removed from the carb because the main jet will not be imersed in the fuel
So you do the on engine test while cranking the engine using the battery, spark plug removed so you do not overload the starter.
2) as Star has already outlined, you do the pressure test with the carb off the engine as it has to be upside down so the weight of the float is closing the valve
Most fuel pumps will pump between 5 to 10 psi so the valve has to be able to with stand that pressure
And I am in Australia so way different time zones
I view the forum on a computer & do so while having breakfast and occasionally when using the computer to research parts or write invoices
So some days I might drop in 20 times & other days only once
Add to that I do have a life so was off for 3 days motorcycling

Please download the Kohler service manual and do a basic service
This includes CLEANING the carb & setting the valve lash
Throwing parts at an engine in the hope that you will luck in a solution is a good way to compound your problem an empty your wallet .
I just about urinate in my trousers from laughter with all the posts that start with "I have changed to oil, oil filter , spark plug & air filter but......"
as if changing the oil makes any difference to a problem other than having no oil
In 300 odd services a year I replace about 5 spark plugs and find about 2 air filters so badly clogged that the mower will not start unless it has been tipped over & the filter is full of oil .

 

[StarTech]

I am a little prejudice here as I run a shop and it is how I make my living. I don't mind helping out other techs, just not the local ones for an obvious reason. They are competitors for my income. Plus them don't have any business having tools of any kind. They do more damage than they fix.

I just got in a Gravely ZTR that one of them so called repair shops repaired. They disable all the safeties and got the mower creeping in neutral so when it starts up when it came in it started moving without anyone at the controls. It took awhile to undo the wiring damage. Now off to stop the creeping. The customer that owns the mower now is wanting restore correctly as he runs a youth center where the kids uses the mower.

These mechanics even give the shade tree mechanic a good name. Now I have been called a shade tree mechanic myself as there are times I work under a shade tree. It is just because I am not stupid and know under tree is cooler than working on the asphalt driving driving when it has a surface temp of 140F with air temps nearly 100F and heat index nearly 115F. This morning actually feels cold at 61F. Since I have been very limited to working the last week. I probably will do one mower today even though it is my day off and that I just cross the 63 mark. With my meds I am suppose to stay out of the direct sun so it looking like I got to get a double carport to work under. Then I be a carport mechanic.

 

[winmod21]

I’d only recommend making a purchase of a leak down tester if you plan on getting into the repair business. I’ve never used an oil pressure tester.

Thanks Rivets. ;-) Was wondering after reading of the tests being suggested on some threads.