JD 445 No Power Under Load

[hardlyrob]

Hi Guys;

I have a JD 445 23hp gas lawn tractor with the Kawasaki v-twin, 511 hours on it. The problem is two part - first it cycles when idling at mid to full throttle (faster, slower, faster etc. - about 1 second interval).

Secondly, it has no power under load. Started to mow the lawn for the first time this season, and engaging the mower deck will stall the tractor. Stepping on the hydro forward can stall it. Not right.

This is the first time I've used it since moving 2 feet of snow back in Feb. with the front end loader. It was cycling then too - but I figured it was water in the fuel, so added dry gas. It still has the same gas in it - about half a tank left.

Any help would be appreciated!

Thanks!

Rob

 

[Dutch445]

couple things to check, you could have
fouled a plug with poor gas. you can
try pulling off plug wires 1 at a time. (use heavy
gloves or insulated pliers if doing it while the motor
is running)when you
do, listen to see if you notice the motor acts
the same as it does now. The other wire should
just about kill it.
if it isn't the plug, it could be a bad coil, of which there
is one on each side of the head where you spark plug
lead comes from. (new plug on the dead cylinder side
with no spark could indicate this, or swap coils from
side to side).
either way, if you were running 1 cylinder for a while, check
your engine oil, you may show an increase in oil level
due to the excess fuel going down in the base, which means
an oil change to remove that gas diluted oil.
there is also a circuit board under the dash, on the
right side behind the sidescreen that has some engine
control, so check the easiest stuff first (spark etc).
and if you do have bad fuel, get it out, change the high
pressure fuel filter under the frame, and start with fresh
known good gas. dry gas added to ethanol isn't a great idea,
as ethanol is alcohol, and drygas is just more alcohol which
dilutes your gasoline and creates an even poorer fuel.

 

[beenthere]

This new member started two threads. Welcome to the forum, but it helps to only start one.

The other thread has the OP response that he thinks the problem is solved.

http://www.tractorbynet.com/forums/owning-operating/204763-jd-445-no-power-under.html

 

[r8nger]

Oops got it

 

[Rob_H]

OK - so I'm not as smart as I thought I was. Here's the current situation:

JD 445 514 hours on it, no electrical problems before this other than a dead battery.

The engine started to cycle at idle in Feb. when I was clearing snow with the loader. It sat until late April, when I changed out the loader, put the mower deck on etc. to make it the Summer version.

Now it is cycling, and running about half power - pretty useless, can't even move it. I searched around on this forum and found similar symptoms for a bad MAP sensor - so I got a new one of those ($260 - Ouch!!). When that showed up, I installed it, and no difference in performance. However, if I disconnect the vacuum line from the sensor it idles fine, and works OK - still low on power.

Based on some other research, I tested the spark, and had a bad coil. This morning I replaced one of the coils, and the engine runs surprisingly well on either cylinder. Now with one new coil, a new MAP and the engine dies completely if the MAP vacuum hose is connected. With it un-connected it idles well, and runs at full power for about 10 minutes before it starts losing power under load. Sometimes it recovers and I can mow a bit, sometimes it stalls out. If I turn it off, and let it sit for a couple of minutes and restart, it runs fine for five or ten minutes then starts cycling and losing power. In any case it runs fine with the mower disengaged.

Any ideas?!? It feels like a sensor / ignition module / computer problem, but I don't know where to look next.

Thanks!

Rob