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Deadguy

Barn rescue 856 running roughly

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I have recently rescued an 856 from sitting in a barn for some years.  After changing the oil, gas, fuel filter, spark plug, and carb it runs fine for a little while, then gets rough and weak.  See the attached video.  Around 40 seconds in is where things start to go downhill.  Any ideas?

IMG_1378.MOV

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Posted (edited)

Ok,

 

So apparently posting videos does not work.  Oh well.

Edited by Deadguy

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Is it worse at high RPMs?

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Posted (edited)

Plugged fuel tank vent ?    Loosen the cap and see if that helps.

 

BTW, the video opened for me.

Edited by Ed Kennell
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Bad fuel pump?

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Glad the video works for someone!  I doubt it is a plugged fuel tank vent, as there is plenty of fuel at the carb.  Fuel pump is an idea.  How long do those stay ok sitting around?

48 minutes ago, Achto said:

Is it worse at high RPMs?

 

It was at full throttle for the entire video,

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13 minutes ago, Deadguy said:

  I doubt it is a plugged fuel tank vent, as there is plenty of fuel at the carb. 

 

 

If there is plenty of fuel at the carb, the pump can not be the problem.     

Does it run better when you spray starter fluid around the throttle shaft.  Could be sucking air.

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Video is taking forever to load, so a couple more thoughts off the top of my head:

 

You say you "changed" the carb, do you mean you replaced it?  Did you also replace the fuel lines?  They could be old and disintegrating, allowing bits of rubber and miscellaneous junk into the carb.

 

How about the points and condenser?

 

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Definitely sounds like it's running out of gas. 

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I have not changed the fuel lines or condenser yet.  The carb was changed out with one from a blown k181 that I already had.  It ran even worse on the old carb.

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I have a condenser, carb gasket set, and fuel lines on the way.  Will keep updated!

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The video played fine it just took  bit to load because it was over 100 meg. Sounds like the float may be sticking and not allowing the fuel to fill the bowl like it should. I would take the float bowl off and look to see if there is any junk in the inlet and see if the float is bent or binding. Too me it sounds like its running low on gas and slow to re-fill the bowl. I would definately do this first before I started throwing parts at it. Its running good so its not a ignition problem as of yet. So, investigate the carb first. How clean is it inside? Gunk inside it from sitting? Partially clogged inlet from the gas line? Float sticking or bent slightly? The pump seems fine by the way.  I couldn't see the fuel in the filter so I would assume you can see at least a partially gas filled filter?

10 minutes ago, Deadguy said:

I have a condenser, carb gasket set, and fuel lines on the way.  Will keep updated!

 

I would do as I suggested first. If you question the fuel pump I would setup a gravity feed to see if it runs better or better yet check the pressure if you have a fuel pressure gauge.  If the pump is indeed good and no float problem is found I would disassemble the carb and boil it out and then blow it out with compressed air and kit it and re-install it.

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The fuel filter was full of gasoline the whole time.  The carb was brand new less than a year ago, but I will take it apart and clean it out.  The fuel lines are dry rotted and a bit sketchy, so they may have put some crud in there.

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29 minutes ago, Deadguy said:

The fuel filter was full of gasoline the whole time.  The carb was brand new less than a year ago, but I will take it apart and clean it out.  The fuel lines are dry rotted and a bit sketchy, so they may have put some crud in there.

 

Try running it at a lower RPM. If it runs good there then throttle up. If it starts to run bad at high RPMs I would lean towards the condenser. You could also borrow a condenser from one of your other :wh: to check if that is the issue.

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It ran about the same (albeit slower) at lower throttle.  I also found a small leak in the head gasket.

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9 hours ago, Deadguy said:

The fuel filter was full of gasoline the whole time.  The carb was brand new less than a year ago, but I will take it apart and clean it out.  The fuel lines are dry rotted and a bit sketchy, so they may have put some crud in there.

 

What you know so far..... Fuel filter is full of gas= fuel pump ok, Fuel lines are rotted = possible particles are causing a problem, Carb was brand new was run and then sat a while? If so passages can get plugged or partially plugged and cause a problem. The idea of robbing parts from a running working engine has never thrilled me. Do you have a volt/ ohm meter possibly with the ability to check the capacitor? If so do a cap check to rule it out. Generally if a cap is bad you will have a tell tale sign of burned or pitted ignition points.

11 hours ago, AMC RULES said:

Definitely sounds like it's running out of gas. 

 

I agree 100%  from what I hear it sounds like its running out of gas or starved.

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You said in your OP that it was changed gas but it almost sounds like it's ingesting water as well. Why not buy some fresh fuel, hang a nice can above the carb and put a fresh line to it for a nice new gravity feed. Take the entire fuel system out of the equation - and you get to see how thirsty these things are. I use a 6" PVC cap with a brass fitting screwed into its center. I have the wife hold it above the carb - one of her many handy uses. If it runs well on nice fresh gas, it's not the carb.

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It only has had fresh fuel since I got it.  The same gasoline in the tank is the same gasoline from the same gas can that everything else I have has gas from, and those all run fine.  No possibility of bad gas or water in the gas. The points look good.   

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Does this tractor still have it's original sediment bowl on it? 

      Image result for garden tractor fuel bowl

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There is no sediment bowl.

I tried running it again this evening.  Same deal, whether the cap is on or off.  Runs smooth until warmed up, then the intermittent stuttering and cutting out in the video.  Now I just have to wait until the parts get here I guess.

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Hey Dead-dude - I was taught that it's always ignition first and, though this sounds like fuel starvation, you've gone though it pretty well for that. What about a hot coil? I don't know what coil this has but, if external auto coil, could be the wrong one (no internal resistor). If a magneto coil, hot breakdown. I don't know what else to offer. My old Honda 550 behaved this way. After about 10 miles in the GA summer, she'd drop to 2 cylinders. Put her aside for an hour and fine again.

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Posted (edited)

Sir,

 

Would you consider looking at the carb adjustments? In info below is for a Kohler carb. The Kohler file below also lists a different carb that was also available that has different jet adjustments. Please note which carb you have and also do write down your adjustment positions. It helps if you can use a magic marker or a touch of finger nail polish to mark the adjustment screw. The adjustments below are for the Kohler carb which is supposed to be the more common carb for this engine.

Keep in mind that even if the same type of carb is taken off and identical engine the carb adjustments can vary because of internal condition, and other factors.

 

Does the carb that you replaced the original with have a low speed adjustment and a high speed adjustment? If so I would like you to count the number of turns or partial turns required to gently and I will repeat gently seat the adjustment screws and write it down. According to Kohler's information the low speed jet should be one and 1/4 turns from the seated position and the high speed or main should be 2 turns. Now, if the carb is a different model or off a different sized engine this figure is going to change. Do this with the engine NOT running and then set the adjustments to what I have mentioned and see if she will start. If she won't start then turn the adjustments back to where they were in the first place get it started and warmed up and let it act up and then adjust the main ( adjustment near the fuel bowl) a little counter clockwise and this will richen up the mixture a tad bit. Note if it starts running any better or not. If it starts running a bit better try a tad more rich and do this in small very small steps. Increase RPM's and see if she starts to lean out and if so richen a little more as needed to obtain a nice runnable condition. Once that is done go to a idle and adjust the low speed for a balance of a good RPM and run ability.

 

Please do report back and advise of a condition change better or worse. I'm thinking that it may be a simple adjustment procedure needed and you have nothing to loose except a little of your time.

http://www.kohlerengines.com/onlinecatalog/pdf/ens_593_f_all.pdf

 

Spark plug at .025 gap? Points at .020? Points unburned or pitted?

Edited by 6bg6ga
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On 7/27/2017 at 6:48 AM, Deadguy said:

The carb was changed out with one from a blown k181 that I already had.  It ran even worse on the old carb.

 

So, it ran bad before the carburetor was changed, and it improved slightly but still runs bad afterwards. Makes me think that it's not the carburetor but a bad fuel delivery system, including the pump and fuel lines. I have seen fuel pumps that work erratically. Because the tank is higher than the carburetor, if the one-way valves in the pump are weak, fuel will flow through the pump and fill the bowl. Engine will run and a weak pump will keep trying to fill the bowl, but if the one-way valve discs are not sealing or the diaphragm is weak, the fuel volume can't keep up with the need.

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Posted (edited)

Post 13 says he has a full fuel filter which should indicate there is enough pressure to both fill the filter and the bowl. It the filter was partually filled I wouldn't dream of questioning what you have said rmaynard.

Why not try adjusting the jets first to rule that out completely if the poster hasn't already done that?

Edited by 6bg6ga

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Posted (edited)

If the fuel filter is between the tank and pump were most of them are,  It will always stay full even with a bad pump.

I have never seen a filter between the pump and carb where a full filter would indicate the pump is working.

Edited by Ed Kennell
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