EX450 won't maintain 2700 rpm for pto speed

[Eyecatcher]

EX450 with 320 hrs on it. Noticed while bush hogging (working it hard) after about an hour, it would no longer reach 2700 rpm, 23 - 2400 max, and blowing blue smoke. Changed outer air filter (expensive) and thought it was ok, but then discing, again after about an hour, same thing. I would think that blue smoke would be oil, but crankcase is full, never has used any oil. Fuel has stabilizer in it. After it cools off, it will turn close to 3000. Seems to have plenty of power. My big concern here, other than an approaching mechanical failure, is use with a pto generator if we have a hurricane. Below 2700 won't give me 60 cycle power.

 

[dieselbeef]

fuel filter..the longer ya run it the less rpm you will get

 

[Katahdin]

I concur it may be a fuel filter issue.

EyeCatcher, you may be overdue for servicing the fuel/water separator. On my LX this is above the rear axle on the right-side from the rear. You'll want to shut-off the fuel valve to that, drain the bowl, remove the bowl, clean it, etc. There is small plastic filter/screen inside that that's also due to be replaced. You can get a filter replacement from a Yanmar dealer, but it may be cleanable.

The spin-on fuel filter on the engine is due at 500hrs. It wouldn't hurt to replace that as well, and if you picked up some bad fuel somewhere, that could expedite the timetable on replacing it. The NAPA replacement number for the spin-on filter 3399, or get the Yanmar one at your dealer.

Hope that helps, let us know how it goes!

 

[Eyecatcher]

Serviced the fuel/water separator yesterday, and it had a lot of mud in the bottom. Plastic screen didn't look too bad, but it's pretty hard to tell just how bad it is. Kinda fun putting it back together and keep the 2 part screen placed properly, but finally got it. I'll get the replacement spin on when I go to town.

 

[Gods Country]

On a side note I replace the fuel element filter annually for this reason, and the main fuel filter every other year. They're relatively cheap and not worth the problems a dirty filter can cause......:2cents:

 

[Katahdin]

All this talk of clogged fuel filters and preventative maintenance inspired me to change my filters as well. Here's some pics of the parts we're talking about....the only mishap in my process was I dropped the fuel separator o-ring somewhere and had to run to the local hardware store to replace it. I had the filters on-hand already. Better to change them now then in January when the water and algae trapped in the filters ices up! :thumbsup:



PS. As I understand it, that red ring in the water separator is supposed to float as in indicator water is in the filter. The ring does not float in fuel.

Also fyi, WIX Filter 533399 (shown) is the same as NAPA filter 3399.

 

[Eyecatcher]

Got the filter changed, and seemed to solve the problem. Worked it pretty good yesterday, and it ran fine. Boy was that spin on dirty on top - much worse than your pix. Pretty rusty in there too. 356 hours, guess it was time. There's another in-line metal filter mounted just below the spin on. Did you change it too?

 

[Katahdin]

I think the inline-metal-filter-looking-thing you're referring to is the fuel pump that primes the lines and filter going to the injector pump. You probably hear it clicking when you turn the ignition key to warm the glow plugs.

 

[tbalz]

hey eyecatcher,

Did the fuel filter fix your problem? I had the same thing happen snowblowing at -10deg this morning. once I hit full operating temp it started blowing blue smoke and only hitting 2300rpm max. I back off the throttle to 2200rpm and the smoke went away. it looks like I will be putting a fuel filter on tonight.

 

[Eyecatcher]

I think you will find you have a dirty fuel filter. I had identical symptoms, only it wasn't cold. I changed the outer air filter, and then the fuel filter. it had a lot of gunk in it. I also changed fuel suppliers. After inspecting the filter, I don't think I was getting clean fuel. This did solve the problem.