BX1500 - Runs rough at full throttle!

DaveInColorado · Jun 3, 2004

I now have 136 hours on this beast and do every bit of maintenance per the schedule with Kubota filters and synthetic Rotella T for engine oil. My boys put more hours on it than I do mowing lawns so this problem could have existed for a week or two prior to me noticing it (though I did ask and they said they didn't notice - duh). When I'm using it, it is usually the FEL, tiller, or box blade and consequently I'm rarely above 1/2 throttle. Tonight I had to drive it about a mile so I put my ear protection on (with radio) and put the pedal to the metal and let her rip up the road at 8 mph. I'm not positive when it happened or if I just didn't notice it at first, but before I reached the destination I started to notice it "missing", then noticed it was smoking just a bit; too much fuel smoke, not burning-oil-engine-on-fire overheated smoke. I had to mow a steep ditch for about an hour at 2/3 throttle, then headed back home at 1/2 throttle. It runs like normal at 1/2 throttle. Arriving home, I removed the air filter to take a look. It was brand new 36 hours ago. I did the Kubota recommendation (I don't like it) and used a little air to blow it out from the inside. Reinstallation didn't change a thing. I guess the next thing I'll do is replace the fuel filter which isn't due until 500 hours. We've had some rain recently and quite a lot of below freezing nights and warm 70 degree days. I guess I could have water in the fuel filter from the temperature cycling. That would not bother me if that is all that I need to change. I've gone through at least 15 gallons of diesel in the last month or two.

Any hints on what might have happened and how to fix it? I checked the Operator's Manual - nothing of any assistance. The water temperature was a little below normal and the water level is fine. I check the oil every week or so and the last time I checked it was still where I left it 36 hours ago - top mark. I didn't hear any weird internal engine noises. Like I said - it feels like a clogged air filter on a gasoline engine but I really don't think that is it. We have grass everywhere we mow and the dust is minimal. However, and a big however, I do have to replace the air filter every 25 hours on little MTD lawn tractor because it clogs up and starts running rich and diluting the oil with gasoline. Cleaning the air filter lets it run another 15 minutes - no more, so I have to replace it. Maybe that indicates that it is dustier here than I estimated.

My son will be using it today to mow a 2 acre field and 1/2 acre lawn. I told him to keep it under 2/3 throttle where it doesn't smoke and still runs good and to bring it back home if things take a turn for the worse.

Just to make things more complicated and screw up your analysis, after putting the air cleaner back on it was running very slow and very strange. A throttle adjustment didn't have any effect so I grabbed the throttle cable to see if it was broken and all of a sudden it started idling normally as soon as I touched it and the throttle worked again. ???? /forums/images/graemlins/confused.gif I'll give the throttle connection a good lookover tomorrow when it is light.

Bird · Jun 3, 2004

The first thing I would check is the fuel filter; maybe change it, but I'd probably drain a little fuel into a clean glass jar, let it sit awhile, and see if there was water in the bottom. And of course, you can mow at whatever speed you want to, but personally, I'd run PTO powered implements at PTO rated speed, which is just almost full throttle.

Mahlon · Jun 3, 2004

Sounds like water in the fuel. Change both fuel filters & drain out/discard about a gallon of fuel in the bottom of the tanks.

regards,

Mahlon

DaveInColorado · Jun 3, 2004

1.) Both fuel filters? Where's the other one? I think I have only one filter and it is easily changed.

2.) Why no water separator? If there was room in there I would considering adding one. The space is tight!

3.) BX - how do you drain fuel from the bottom of the tank? It is molded plastic and stretches 4.5 gallons across a large area under the seat.

4.) Will it never clear itself?

5.) This makes sense because I had just added 3 gallons of fuel. I never leave the cap open for even a second after refueling but I do leave the can out in the rain. I'll change my evil ways and put it under something.

6.) Kubota fuel filter - who cares? It is just a simple inline filter. My Kubota dealer takes a minimum of 1hr 15min for a round trip just to get a dumb fuel filter. I'll get two, but I bet I could find something at AutoZone to fit.

Mahlon · Jun 3, 2004

( 1.) Both fuel filters? Where's the other one? I think I have only one filter and it is easily changed.

2.) Why no water separator? If there was room in there I would considering adding one. The space is tight!

3.) BX - how do you drain fuel from the bottom of the tank? It is molded plastic and stretches 4.5 gallons across a large area under the seat.

4.) Will it never clear itself?

5.) This makes sense because I had just added 3 gallons of fuel. I never leave the cap open for even a second after refueling but I do leave the can out in the rain. I'll change my evil ways and put it under something.

6.) Kubota fuel filter - who cares? It is just a simple inline filter. My Kubota dealer takes a minimum of 1hr 15min for a round trip just to get a dumb fuel filter. I'll get two, but I bet I could find something at AutoZone to fit. )

On a BX2200 the first fuel filter is under the floor pan, plumbed between the fuel tank outlet and the electric fuel pump. The second filter is in the engine compartment. There may be only one filter on a 1500, if so I'd consider adding the second one.

I've drained fuel by pinching the hose with clamps, then disconnecting it from the first filter's inlet. Get a BIG container. Have some Oil Dri or kitty litter at hand.

I don't like the absence of a water separator either. I've got a Yanmar filter/bowl that I'm trying to figure out how to plumb in/mount. Once I figure that out I'll post it.

It >may< clear itself, but you're asking for trouble if you do so. Fuel injection system parts are expensive to replace and I doubt that water corrosion damage is covered under warranty. If you get enough water into the combustion chamber you might break Really Expensive Things.

I've been searching for an exact equivalent in the Purolator line but haven't found one. I think there's a Wix equivalent, though. I'd want an exact equivalent so that I have some assurance that the filter's particle size is the same.

regards,

Mahlon

MadReferee · Jun 3, 2004

( 2.) Why no water separator? If there was room in there I would considering adding one. The space is tight!)

Get yourself a Mr Funnel, the standard one will do. You will be surprised how much water is actually in 5 gallons of pump or off-road diesel. Website is www.mrfunnel.com

Do a search here for Mr Funnel and read what other TBNers have said about them.

kevinj · Jun 3, 2004

I have a bx1500 and the filters are the same as a bx2200. They are a bit of a challenge but vise grip makes a hose pinch plier which makes it a bunch easier. If you go to wix you can get a cross reference from the kubota part #. I have not used any wix so I do not know if th OD is the same, this would be important as the filter clamps on the body.

kevinj · Jun 3, 2004

( Why no water separator? If there was room in there I would considering adding one. The space is tight!
)

I think this is the reason for 2 filters. They are see thru so if you clean them and put a light behind them you can see if there is water in the bottom of them.

DaveInColorado · Jun 4, 2004

After finding and fixing the problem last night, I reflect wistfully upon the old "Blind Men and the Elephant" poem. I appreciate the opinions, but all were way off the mark! I'm a firm believer that one must make mistakes in order to learn from them and thereby gain experience and wisdom in life. I also have a certain amount of pride that I carry around, knowing that I am a trusted person in many different ways. People look up from their toils as I walk by, thinking "I wish I was as skilled as Dave in all things mechanical!"

The conclusion is that this was a very important learning experience for me. So important was it that I must horde my knowledge so that I can later annoint my followers with it and keep my Grand Exalted Kubota Master Mechanic title intact and possibly make a few bucks on the side. I think I deserve this title because I make more mistakes than most and consequently my knowledge has increased exponentially in a very short amount of time.

I will award one tilt meter to the first person who correctly guesses the cause of the problem!

JWE · Jun 4, 2004

( I will award one tilt meter to the first person who correctly guesses the cause of the problem! )

Dave, I am absolutely sure that I know the cause of your problem. You fell and hit your head.
Please send the tilt meter!

John