25 HP Kolher Comman (Cub Cadet LT1050) Surging acting like out of gas

[taxidermist]

Get a spark tester and run your mower until it dies then check if you still have spark. It is a cheep way to rule out the coil. Where in MI are you located?

Rob

 

[sukey]

I'm just west of Lansing.

I've tried to check the spark a little- I've pulled the wires when it's running (to see if a loss of spark would replicate the issue) and the engine bogs down but doesn't stall out like when it's having the issue. However at this point i'm not rulling anything out, i'm going to get a spark tester or maybe use an extra plug to do a quick test. If it was spark or engine related i just don't understand how a new carb would make the problem better.

What do you guys think about these "theories"
1. A clogged up crackcase breather causing a pressure build up? OR
2. A minor headgasket leak causing exhaust gases to blow back into the intake system (only rears it's head when the engine gets warmed up??)

 

[taxidermist]

I dont think is a head gasket problem. You can check the CC breather while its running to see if its plugged. I am not sure about the new carb making it a little better. Check the spark and get back to us and lets go from there.
Rob

 

[reddragon]

try running with gas cap off....if its vent is plugged...it could do a similar thing

 

[RAJOD]

I have a CV16 Kohler Twin doing the same thing. Acts like its being starved of gas after running 15 min. Leave it off a few minutes and it runs fine again.

I replaced the fuel pump but did not help. Checked hoses all seemed ok.

1. Could be blocked oil separator causing the fuel pump not to work well
2. Blocked gas tank vent. Will check this out
3. Loose Dipstick cap - not sure if this would lower the crankcase pressure enough to cause fuel pump not to work.
4. Fuel filter blocked. checking this too.
5. Gasket leak.

Since mine runs great I might just hook up an electric fuel pump and not worry about the pulse type fuel pump.

I'll post back if i figure it out.

 

[RAJOD]

I was having some issues with my Toro 266H (16Hp V twin Kohler command)

It would die after around 20 minutes of driving. I would let it sit for 5 minutes and it would run great again. It seemed like it was starving for fuel.

Funny thing was my wife could mow all day and it would run fine for her.

I bought a new Fuel pump for it but it did not do any good. Then i thought maybe the fuel line could be cracked.

Long story short. It was due to the fuel line running between the gas tank and the frame. I had drained the tank in the spring and the line must have slid under the fuel tank when I put it back together.

I weigh 230 and mife wife is 115Lbs. She was not heavy enough to crush the gas line so the mower ran fine. I was just heavy enough to compress the line after like 20 min if mowing.

Anyway I took it apart and moved the fuel line in the proper place.

I also have a new filter and fuel pump.

It runs great now. My wife thinks i did it to get out of mowing

 

[crewdog]

Starting cutting grass this season and I'm having the same problem you were having last year.Did you ever figure out what the problem was.Somebody said to try replacing the fuel shut off solenoid. Any ideas would be helpfull.Thanks

 

[sukey]

Sorry not to add an update in so long-

Unfortunately I never really figured this issue out. However I've narrowed it down to something with the air intake/fuel supply.

If I run the mower on about half power it seems to be less of an issue (cub cadet salesman said to run at full throttle but the 25 hp engine cuts fine at half throttle)

Also to really make this weird- I noticed that if I spray the air filter with carb cleaner the thing runs great. I'm embarrassed to admit that I keep a can of carb cleaner on my tractor and quick spray the filter if it starts acting up. (i know it's not safe, and i know it's a "duct tape" fix- that's why i'm embarrassed)

I'm going to pick up a new air filter tomorrow and see what difference that makes. I did notice my mower is missing the oil soaked pre-filter that is in the book for this model- I'm wondering if too much air flow has caused this issue and soaking the filter somehow helps, but this doesn't really add up to me. I'll post more when i know if i don't set myself on fire while mowing.

 

[Rivets]

Have you changed the pulse line going to the pump and where it is attached to the engine. You could have a crack at the point where the pulse line meets the block which opens when it gets warm. I would also check valve clearance. If it is to close heat expansion may cause the valves to same open to long. Also, I don't know the spec of you engine, may have hydraulic litters are pumping up.

 

[sukey]

Have you changed the pulse line going to the pump and where it is attached to the engine. You could have a crack at the point where the pulse line meets the block which opens when it gets warm. I would also check valve clearance. If it is to close heat expansion may cause the valves to same open to long. Also, I don't know the spec of you engine, may have hydraulic litters are pumping up.

Pulse is good- I've replaced all the lines, clamps, and checked for cracks. I event checked fuel pump flow by pulling off the outlet and turning the engine over- it spits a strong flow of fuel.

As far as the heat expansion - I would imagine that would be worse on hot days opposed to cool days- I mowed when it was 50 out yesterday and it was the same as 90 degree day. I'm not sure how to check the valve clearance- is it difficult- and it is adjustable?