Z4202 Fuel Consumption Increase

[Dreaded]

From your statement. You said exaust smells rich. That indicates to rich of a air/fuel mixture caused by carburetor misadjusted or need cleaning.The carburetor could just need a good cleaning, if the air ports that control the air fuel mixture is clogged they will cause it to run rich because it will draw more fuel than air. I do not think the valves would cause this though after that long of use they need adjusting.
You stated it ran smooth and I take it to mean no loss of power. You also could have a problem with a mechanical issue that is loading the engine and lowering the rpm that would cause the mowers governor to open throttle more to maintain rpm. This could be as simple as a belt idler bearing making it harder for the engine to maintain rpm. So this problem can be caused by a lot of things.
As DeadmanRoss316 said start with the easiest and work your way through it then if you don't find the problem go back and check everything again. It is easy to miss some simple thing that is causing the problem.

 

[SPIKER]

Hello, All. I have a 2009 Z4202, owned since new and have been meticulous with servicing. Done about 350-360 hours on the Kohler Courage, which purrs like a kitten. I have observed a noticeable increase in fuel consumption over the last 3-4 months. I have also noticed the exhaust smells a bit rich. I intend to adjust the valves (for the first time) to see if that improves the situation Does anyone have other suggestions? And, as a final, but not unrelated, query - has anyone fitted a fuel gauge to their Z4202?

carb needle &seat gone bad

 

[Smithsonite]

Air filter first, then check bowl as others have mentioned. Sticking needles are common with the s#$* fuel we have today.

 

[Dreaded]

carb needle &seat gone bad

I have found that in most cases of the needle and seat gone bad or sticking that it is either not going to get fuel or it is going to flood out. The way he stated his problem is not indictive of a needle seat problem because if it is even slightly seating open it will cause flooding that will make it hard to start after a short period of time and he did not indicate he had this problem.

 

[grumpyunk]

Dreaded, the time I had the problem with the Kohler, after the leak was cured, the fuel consumption went from over 1 tank to do the front yard only, to about 1 tank to do front and back yards. Significant reduction in fuel consumption doing the same amount of mowing. The only thing changed was the needle and seat.
Others' experience may differ, and likely will.
If using a manual shutoff, a leaky float valve or worn needle/seat could just allow a functionally higher level of fuel in the bowl, without causing external leakage. I thnk that's what I had back when.
tom

 

[Dreaded]

Dreaded, the time I had the problem with the Kohler, after the leak was cured, the fuel consumption went from over 1 tank to do the front yard only, to about 1 tank to do front and back yards. Significant reduction in fuel consumption doing the same amount of mowing. The only thing changed was the needle and seat.
Others' experience may differ, and likely will.
If using a manual shutoff, a leaky float valve or worn needle/seat could just allow a functionally higher level of fuel in the bowl, without causing external leakage. I thnk that's what I had back when.
to

Tom I work on a lot of mowers during the summer. I have not had an instance of the needle and seat causing this but I have had a float that caused the carb to be overfilled by being set to high. This caused a higher fuel consumption.On this occasion no one had been in the carb so all I can assume is that it became set higher by use. I test carbs float level by using a clear tube off of the drain. With clear tube raised beside the carb so you can see the fuel level. It should be level with the bowl gasket. In your case the new needle and seat may have correct the float hight setting.

 

[Smithsonite]

I've seen this countless times as well, Dreaded.

 

[chuckpen]

Well,

Generally, gas can go two places. Fire or into the oil. how does the oil smell? I do like the idea of a poorly adjusted choke as well. How does the plug look? rich or lean?

 

[Dreaded]

I've seen this countless times as well, Dreaded.

Everytime I have seen a needle/seat problem has been that either it flooded the engine causing it to smoke white exuast or go into the oil and not run smooth or you get no fuel. I have found most of the time the needle/seat will not cut off the fuel flow if the needle/seat is bad and there by flooding the engine oil.
I am not saying the the needle/seat was not a problem for you. If it has to high a level in the carb then it is the float not adjusted correctly. The wear on the needle/seat can cause the float to raise higher (the rubber end of the needle will wear a grove that allows the float to come up higher, it does not take much wear to raise the float high enough to cause this symptom) or the seat can come unseated and cause the float to be lower. This is what you might be seeing and it might not be that the needle/seat needs replacing it may just need the float adjusted. I do not usually replace the needle/seats in a carb. The reason is our fuel is so bad now that it will build up residue in the fuel tubes that run through the carb. I have soaked many overnight in carb cleaner and still not got the tubes cleaned out. So if I have a problem that require a rebuild of the carb and cleaning does not fix it I just replace it.

Next time you see this try checking the fuel level by using a clear tube to see exactly where the level is then try adjusting the float to get the proper level. I have wasted many hours trying to fix carbs and decided to do some testing of my own such as measuring the needle height in the seat then replacing the needle/seat and re measuring. From this I found in the one I tested that the needle was higher with the new seat/needle causing the float to be lower. The float level cam back to factory setting and fuel level came down to the correct point. This was on a carb that the customer used StayBill in all his fuel so the carb was very clean. This carb did not show any build up but it flooded into the oil. In this case I did replace the needle/seat but because the carb was not dirty and I used it as a test.

 

[Smithsonite]

I have seen every single combination thereof. I would say 95% of the time they're either filling the crankcase with gas, or starving the bowl dry, but I've also seen everything in between as well. MA fuel SUCKS.