Loss of power YT3600

[Dirtbag]

I was wondering if any of you have had a situation like mine that you might be able to help me with?  When reaching an incline with the PTO on, my mower slows and the motor begins to shake as if it doesn't have enough power to climb the hill.  The governor is holding the throttle wide open, so it would seem that it's not getting enough fuel.  I went through the carb and blew out the jets and passages, but saw no issues.  I've replaced an out of spec coil, spark plug wire, cap and spark plug.  The maximum compression according to the maintenance manual is 142 lbs., and mine is 138, so that isn't the problem.  I replaced all the bearings on the deck last week.  A friend mentioned that his mower was acting the same way and that he was told that his hydrostatic drive was the cause, so I drained the fluid and replaced it with 40 weight based on a forum recommendation, yet still no change.  I've owned this lawn tractor for almost twenty years and it's been a good one, but I'm not sure what else to try.  Any ideas?

[bilgrotie]

Hello, a method that I use to trouble shoot fuel systems is to use an external fuel tank that I can place above the carburetor providing gravity feed fuel supply. CAUTION, you will need to disconnect the fuel line from the tank to the pump or you will have fuel shooting out of the pump when the engine starts.  If that cures the problem check the fuel pump(my 6700 has one) and also flush the fuel lines. Some tanks have an internal filter that can become clogged.

[Dirtbag]

I replaced the fuel filter last year and tested the fuel pump.  Fuel supply doesn't seem to be the problem.  The engine starts and runs fine.  I'm going to double-check the valve timing.  Thanks

[bilgrotie]

Hello, does the tractor have its' regular amount of power on level ground, will it pull a car or truck?

 The reason I mentioned using a gravity feed fuel supply is that my next door neighbor had the same problem that you are having. His mower would cut the flat front lawn just fine but would miss and die when working on the sloped back yard. After my son replaced the filter and rodded out the fuel line the tractor ran fine. The fuel line would pass enough fuel for partial throttle but when more power was called for the carburetor would not receive enough fuel and the mixture would lean out and the engine would die.
 
Have you tried apply partial choke when the power falls off, I have a Yamaha motorcycle that only runs when the choke is partially on. I will get to those carbs someday.

[rattosh51]

Agree with Bilgrote, need to see if can pull something on level ground. If it can't handle the load,
then I would check the float adjustment, make sure there is no air filter restriction, no kinked or weak
fuel lines. 20-yr old fuel lines may start to collapse when under load, so it may be worth running new ones.

[RAB5050]

Although I tend to agree its a fuel problem likely the pump,when I turn on the ignition and wait a split second for the pump to come up to full pressure I can here a slight creaking as the fuel lines adjust to the higher pressure. Having said that if you haven't looked at the differential oil lately you should. My mower was a gift the first owner had it sixteen years and never changed it. I changed it out and it had turned to a kind of jello consistency. It may have been robbing a few HP.
RB

[Dirtbag]

The mower doesn't seem to bad with the PTO off, but when mowing, it only takes a slight grade to make the engine begin to shake.  I haven't tried the choke, but I just went through the carb and everything checked out including the float level.  I pulled the engine out a couple years ago to replace the gasket on the front cover and had to cut the gas line off the carb to get it off.  This left little slack in the line, which could possibly cause a restriction.  I'll replace the fuel lines this weekend, test the fuel pump and replace the transmission fluid.  Thanks everyone for the feedback.  

[sparkless]

dirtbag hello, i'm sorry i have no answers for your problem and i hope you find a solution to them soon. something you talked about in in one of your posting caught my eye. you made note that you placed a nonspec coil into your tractor. i really need help finding one for my yt6700. any help? thank you, sparkless

[Dirtbag]

I looked at cyclepartsnation.com and found under generator for your model two TCI units (exploded view), part # (JE8-85630-00-00).  They don't carry them, but if this is the part you need, I found them at yocracing.com for $68.06 each.  Once on their site, scroll down to generator accessories, then click the same heading on the next page.  This will open a screen with a quick search for you to plug in the part #.  You might search this part number and find a better deal, but at least they're still available.