Onan 24 Problems

DouginUtah · July 09, 2003, 01:08:28 PM

The last time I used my LT30 I ended up having problems keeping the engine working. Here is what happens. I engage the belts and start cutting. After about 10 seconds it acts like it was out of gas and starts to die. I release the belts and it idles. When it first happened I suspected water in the gas and dumped half a bottle of Heet into the gas tank. This seemed to help considerably for a short time. Then it continued the rev and die routine. I tried pumping gas as it was dying using the in-line squeeze bulb. Sometimes this would help but it ended up dying if I kept cutting. Before using it I had let it sit for several months but I did empty the gas tank and fill it with new gas.

My thinking now is that I should clean the carb, thoroughly, by tearing it down and rebuilding it.

I'm wondering if any other Onan 24 owners have experienced this type of problem and how it turned out. Any advice on rebuilding the carb? :-/

BTW, the log I was sawing is at this link:
http://www.xmission.com/~sherwin/wm_ash.jpg
It was a 36 dia. ash – had to use an axe to make clearance for the saw guides. Got some beautiful 21" wide boards from it. And, NO, that is not Bibbyman. ;D

-Doug

Bibbyman · July 09, 2003, 01:14:25 PM

Who ever he is, he's a snappy dresser! 8)

Back when we were running engines. (had an onan 20, 24, B&S 18 and Kohlor 25) First thing I'd do is change the gas filter. I'd buy a dozen at a time. Most of the time that would fix it. Could it also be the fuel pump?

Here is the Bibbyman that dropped in to help a fellow WM owner in Durango, CO.

biziedizie · July 09, 2003, 02:48:31 PM

  I would say replace the inline squeeze bulb and that will fix it.
  I used to have problems like yours with a boat that I used to own and years later I had the same problems with another boat and both times it was the bulb.


   Steve

Bro. Noble · July 09, 2003, 02:53:55 PM

We bought our last WM from a fellow that had let it set a long time without draining the gas. It would run real rich like it was choked (it wasn't) and the fumes were awful. I cleaned it while still on the engine with no improvement. WM said to adjust the float and told me just how but that didn't help either. I called to order a needle and seat but the only carb parts they had were high altitude kits. I ordered one figuring what I needed was more air and less gas and it was just a different needle and seat anyway. When it came it didn't resemble the one on my Onan 24.

Took the DanG thing off to clean it corectly. Found a diaphram in it that had lost a good part of the rubber coating. I figured a new diphram would cure all my problems. The engine parts book showed two different carbs neither had a diaphram. Called the local Onan guy and told him the model stamped on the carb. He called back and said Onan said my number wasn't any good and they didn't have a carb with a diaphram in it. He suggested I buy the correct carb. I agreed as I was tired fooling with it and didn't see a better alternative. When it came it was exactly like the old one including the modle number stamped on it------and the diaphram. The thing runs great and has much more power than before. Uses lots less gas and the exhaust is clean.

I believe was a modle 6400 made by Nikki. The diaphram is on the front under a plate with three schrews. If you have one of those, that may be your problem. Ours is a 96 model.

Just read Steve's post. I'd try that first as it would be easier and cheaper. Looks to me like onde you get the line full to the pump and filter, that the bulb doesn't come into play, but I don't know. Let us know what happens.

Good luck

Noble

biziedizie · July 09, 2003, 03:18:13 PM

K I didn't get to finish my post as a nagging customer just called. :D :D
  The bulb not only gets the carb primed it also acts as a siphone. There's a small check valve in there as well to keep the fuel kinda under pressure. If there's any sort of leak where air can get into the bulb it releases the presure and the motor will die. :(
  Now this ain't the best way to test to see if the bulb is hooped but it will give you an idea. 8)
  Prime the carb and fire it up and squeeze the bulb very gently and slowly and see if the motor keeps running. Don't squeeze it too fast as it will kill the motor.
  I think them bulbs are about 3 buxs so it's a cheap fix.

   Steve

biziedizie · July 09, 2003, 03:22:01 PM

Almost forgot!
Hey Noble is your mill gravity fed? When you mentioned that your carb has a diaphram in it that was the first thing that hit my mind.

Steve

Tom · July 09, 2003, 04:16:18 PM

I used to run into this problem all the time.

The first thing I did was install a glass sediment bowl in the gas line where I could see it. You can get them from NAPA or Genuine and probably Ag stores. I was surprised to find that everybody doesn't handle them. That catches water before it reaches your pump.

I found that the heat of the day expanded the gas in the tank and when it would cool that night, water would get sucked into the tank through the gaskets, etc. Dew is bad but rain is almost a surety.

To make the engine run again here is what I did.

Pour all the gas out of the tank or siphon it out to get rid of the water.
Put the same gas back if you want but leave the water out. :D

Dump the water from the sediment bowl.

Take the hose off of the pump and purge the pump. (you can use the starter but be careful)

There is a bolt on the side of the carburetor that faces the gas tank. Unscrew this bolt and drain all the old gas and water from the carburetor.

Put the bolt back but don't over tighten.(no gasket but there may be a flat metal washer, don't lose it.)

It should run till next time.

The best thing you can do for yourself is install a glass sediment bowl. It makes filters last almost forever too.

Larry · July 09, 2003, 04:23:48 PM

Nice looking ash Doug. I think ash is neglected, under utilized, and way under priced.

Got any secrets on how you keep the pitch off the band when cutting 21" wide ash boards?

Kevin_H. · July 09, 2003, 04:46:10 PM

I have had the same kinds of problems, The last time it was a bad O ring in the quick connect on the fuel tank, It had a bad spot in it and would keep the little valve in the quick connect from opening all the way, Thus restricting fuel.

I also change my fuel filter every time I change the oil, doest cost much and one less thing you have to worry about when your 50 mi from home sawing.

DouginUtah · July 10, 2003, 01:32:14 PM

You have given me some good suggestions. There is some information that I left out that I ought to add.

When I bought this mill, the previous owner had modified it, as WoodMizer puts it, "extensively". I suspect the mill was sold originally with a smaller engine and had the Onan added later. Consequently, I don't know what is stock WoodMizer and what is an add-on. The fuel tank is a boat tank with a modified washing machine wringer roller supporting it. Last fall I replaced the fuel hoses and fuel filter. However, I don't remember changing the squeeze bulb primer. I would never have suspected that but since Steve mentioned it I think it might be the problem as it doesn't feel the same as it used to. (It used to get hard when the carb was full, now I can squeeze and squeeze and it doesn't get hard.) So the bulb will be the first thing I change.

The fuel tank is about 6 to 8 inches below the carb. I'm not sure what the fuel pump on this engine looks like. There is "something" between the fuel filter and carb which is neither electrical nor mechanical that one would guess to be the pump but I don't know how it works.
I just went out to check on the pump and it seems there *is* something going though the cover so it may have an electrical connection. If so, I guess I could hook up a line to a gallon jug and see if it is pumping fuel.

I have put up a temporary page with a few pictures to show what I have.
http://www.xmission.com/~sherwin/temp1.htm

If the bulb replacement doesn't do the job then I guess I will look at the connector to the tank. (leaking o-ring?).

Thanks for all the help and suggestions. I just want to get this thing running properly so that I can sell it in good conscience before I move into the old folks home.

-Doug

(Larry C.: I'm going to try and do a new post concerning pitch, etc. Maybe next week . It will have a subject of "Push-off".

Tom · July 10, 2003, 03:03:13 PM

In your second picture, that square object above the filter is the pump. I don't know the mechanics of it but, believe me, it pumps gas.

On the bottom left of your picture is a spring and you have the fuel line running behing it. That's were my sediment bowl is installed.

If your priming bulb doesn't get tight, then the check valves inside are probably not working and it isn't pumping. That would be a cheap fix. (get a sediment bowl when you go buy the new primer bulb :D) oh! take a small piece of the hose so you can be sure that you get one that has the same size fittings.

You still may have a bit of water in the carb bowl. Drain it. It doesn't take but a moment. You may be burning the gas off of the top of the water in the bowl and not getting enough back in quick enough and are starving the engine. An engine will recrank in a situation like that and idle fine but hesitates to run.

Your carb picture seems to be taken from the front of the engine. The bolt I'm talking about is the brass looking one on the right side of the carb as you look at the picture.

DouginUtah · July 10, 2003, 03:22:13 PM

Tom,

Thanks for the reply. Regarding the draining of the carb, would it be that large brass "screw-head" to the right side of the carb (see picture) that would need to be loosened to drain the bowl?

-Doug

Larry · July 10, 2003, 03:36:58 PM

That fuel pump looks similar to the one on my Briggs. If it is the same all it has is a rubber diaphragm with air on one side and fuel on the other side. Think maybe it pumps from vibration off the motor but not for sure.

If my motor sets for a while like during July - August the diaphragm dries out and won't pump good until fuel soaks back in. If the diaphragm has a crack gives the same symptoms you are having.

shopteacher · July 10, 2003, 04:24:14 PM

When I was student teaching, I was teaching a graphics class and mentioned the diaphragm in a 35mm camera, big mistake. :D :D :D The girls all turned red and all the guys bust out laughing.

D._Frederick · July 10, 2003, 05:12:43 PM

The fuel pump on the Onan is air operated by the impules created by pistons in the crank case.

Minnesota_boy · July 10, 2003, 05:42:12 PM

If you have recently replaced the fuel line, you may have done as I did and missed a loop to feed it through between the engine supports. it takes a bit of running, but the fuel line will pinch when the engine is engaged and eventually crack there and let in a bit of air. Since air pumps easier than fuel, all the carb gets is air and dies under load. Mine does it occasionally now. I'll have to replace that fuel line as soon as I get the mill back home.

Bro. Noble · July 10, 2003, 06:37:36 PM

Doug,

That is the fuel pump just above the filter. On your carb, that circular plate with three screws has a diaphram behind it (at least on ours). If the other remedies don't help you, check that diaphram.

isawlogs · July 11, 2003, 10:35:34 PM

I also replaced my gas line and had the same probleme hapen, pin hole in the line and engin would die out under load r&r gas line and solved it .
Good luck

ladylake · July 12, 2003, 06:11:40 AM

Doug
I'd check the vent on your tank, can't suck fuel out of a vacume. You said it ran fine for a while after adding heat which would have let air in the tank at the same time. Steve

johnjbc · July 12, 2003, 10:32:52 AM

My Wheelhorse Garden Tractor has the same pump. It is a diaphragm
pump. There is a hose that makes a connection from one side of the diaphragm to the crankcase of the motor . When the piston goes up and down the bottom of the piston causes the pressure behind the fuel pump diaphragm to push it in and out pumping the gas on the other side of the diaphragm . There are check valves on the inlet and outlet fuel connections that allow it to pump. The check valves are little flaps over passages in the metal. Works just like the fuel pump in a chain saw carb.
Several years ago my farm tank got low so I tilted it to fill the tractor and got a lot of water/rust in the tractor. Even after cleaning it out I had trouble with the pump loosing prime if it set over night. Had to disconnect one end of the fuel pump and suck until fuel started coming into the filter. Never did develop a taste for gas. :

:

cut2size · July 16, 2003, 08:56:27 PM

I have had a similar problem with my 24 hp onan on several occasions. Once it was the spark plug wire, it has also been the squeeze ball twice. Take the gas line loose from the exit side of the ball and see if gas flows when pressure is applied. I also had a problem where the butterfly on the carb was not completely open and got similar results. That time I changed both spark plugs first. The air filter can also become so clogged that the engine will not perform under load.
If anyone has changed engines because of engine failure, I would be interested in buying the engine shroud as mine has succumbed to metal fatigue.
David