CT122 losing power

[No Guns Here]

I have a CT122 (not sure of the year). It's been a champ since I got it a couple of years ago. Last week it started randomly losing rpms/power. With load, without load, in gear, out of gear. I can set the throttle at say 2500rpm and after a minute or three it will start backing down. Sometimes it will run back up, sometimes it will just drop RPM's until it dies. Additionally, the tach used to stay rock steady wherever I set it. Now, when idling it bounces around a bit.

I've refilled with new diesel and changed the fuel filter. The air filter is clean and she is full of oil. The battery tests fine and strong. I see no fuel leaks in the engine bay.

What should I look at? I'm not really a mechanic but between google, me, my son and my FIL we usually figure stuff out.

 

[milkman636]

Since you say the RPMs and power come back, fuel delivery fluctuation is the most likely cause, Are there any additional screens/fitters at the fuel tank outlet on that model? One of the benefits of many older models is gravity feed to the fuel filter. You can probably confirm there's a good steady flow of fuel into the main fuel filter by simply taking it apart again and watching fuel drain through for a little bit. If you don't get a steady flow you can chase the line back to the tank and check for obstructions. There may even be junk in the tank that affects outflow.

 

[tman1020]

Sounds like exhaust blockage or fuel delivery to me.

 

[milkman636]

Tman has a good point about exhaust restriction being a possibility too. On my larger model there is a plug in the bottom of the muffler that I’m supposed to remove periodically to let any accumulated soot blow out of. The plug is removed then the engine gets started and run at working speed for a bit. I’ve never had any real noticeable amount come out personally. But it definitely is another quick check you could perform. If it doesn’t have a plug you could also just pull the muffler and check for obstruction the old fashioned way too.