97 case 1818

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Tom W

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May 19, 2024
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9
I have a case 1997,1818, with an onan p218. It developed a flooding out problem. Its what I think is happening.

Starts fine runs good at idle and wot. As soon as I tilt the bucket down and lift the front end up it starts back firing through the exhaust as well as pops through the carb. Why I belive its flooding is if I put my hand over the top of the carb for a couple seconds I get raw fuel on my hand like a noticeable amount. It's wet. Seems like good vacuum as well. I can smell raw fuel as well. I tilt the bucket up to return the machine to level and
It runs fine. It does the same under load if I'm digging dirt etc. It seems to run fine at wot as I'm driving across a flat area. If I'm on an incline it does the same, coughing popping etc.
I took the top of the carb off and cleaned out the bowl and needle valve as well as what I could without removing the carb from the intake. I am stumped. Any thoughts?
 

brdgbldr

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Jun 1, 2012
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1,258
I have a case 1997,1818, with an onan p218. It developed a flooding out problem. Its what I think is happening.

Starts fine runs good at idle and wot. As soon as I tilt the bucket down and lift the front end up it starts back firing through the exhaust as well as pops through the carb. Why I belive its flooding is if I put my hand over the top of the carb for a couple seconds I get raw fuel on my hand like a noticeable amount. It's wet. Seems like good vacuum as well. I can smell raw fuel as well. I tilt the bucket up to return the machine to level and
It runs fine. It does the same under load if I'm digging dirt etc. It seems to run fine at wot as I'm driving across a flat area. If I'm on an incline it does the same, coughing popping etc.
I took the top of the carb off and cleaned out the bowl and needle valve as well as what I could without removing the carb from the intake. I am stumped. Any thoughts?
I am not familiar with that machine but it sounds like a governor problem.
 

brdgbldr

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Jun 1, 2012
Messages
1,258
Can you explain that a bit?
A governor automatically increases the throttle when the machine is under load to give it more power. Depending on the type of governor on the machine, It may not be opening the carb to give it enough air to burn the extra fuel needed. It could be a simple linkage problem or the governor could be shot.

Of course, as I stated before, I am not familiar with that particular machine. I did look up the specs and see that it does have a mechanical governor.
 

foton

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Mar 1, 2018
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1,345
along the same line kinda,, I was thinking the carb. float or the needle and seat not working as it should causing the flooding. yeah I know nothing about that machine also.
 

foton

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Mar 1, 2018
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1,345
there is a arm that goes to a shaft thru the engine block that thru springs hooks to the throddle cable with the engine running if you push on that shaft to raise engine speed you should feel it push back, that is not a way of adjusting it ,that will tell you if it is working some. there are you tube videos on small engines that will expain it better. make sure you get it right, engine damage can happen if gotten wrong.
 

pogo

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Joined
Mar 29, 2010
Messages
59
I have a case 1997,1818, with an onan p218. It developed a flooding out problem. Its what I think is happening.

Starts fine runs good at idle and wot. As soon as I tilt the bucket down and lift the front end up it starts back firing through the exhaust as well as pops through the carb. Why I belive its flooding is if I put my hand over the top of the carb for a couple seconds I get raw fuel on my hand like a noticeable amount. It's wet. Seems like good vacuum as well. I can smell raw fuel as well. I tilt the bucket up to return the machine to level and
It runs fine. It does the same under load if I'm digging dirt etc. It seems to run fine at wot as I'm driving across a flat area. If I'm on an incline it does the same, coughing popping etc.
I took the top of the carb off and cleaned out the bowl and needle valve as well as what I could without removing the carb from the intake. I am stumped. Any thoughts?
I would get a rebuild kit for the carb, sounds like a float issue.
 
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Tom W

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May 19, 2024
Messages
9
I have the kit and I'll check the gov later this week. Thank you and I'll report back
 
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Tom W

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May 19, 2024
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9
I ran it yesterday. The govenor seems to be working. The butterfly in the carb is adjusting while opening and closing the throttle. It is pouring gas into the carb wether wot or not. Pulling it all apart this weekend. Thank you.
 

foton

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Mar 1, 2018
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1,345
sometimes the float will absorb gas if a hard foam type or if it is brass can crack and hold fuel fuel and will not close the needle and seat causing flooding just make sure to check that out.
 
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Tom W

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May 19, 2024
Messages
9
Carb soaked in cleaner for 2 days. New gaskets, float and needle valve. Intake and exhaust manifold gaskets new. Same crap. Runs good at idle or wot. On a grade starts to back fire and sputter. Gov seems to be working it is pulling the butterfly open and closed when opening closing the throttle. I can't find a oil pressure sending unit that would be cuasing this issue. I can't for life of me understand this.
 

haymaker

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Mar 14, 2023
Messages
165
My 91 Bobcat 543B would start and idle but if you tried to throttle up it would backfire through the carb.
It was the what Bobcat called the engine speed sensor.
Some called it a crankshaft position sensor. It was a sensor that picked up a spot on the flywheel that was telling the spark control module the timing was not advancing properly.
This 542B has a very early distributor less ignition system. I would think the late 90s Case would have a similar system.
Just something to think about if it is not the carb.
 

foton

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Mar 1, 2018
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some of the onans you can set the timing, if it is off that could cause a backfire condition, so that is something else to check and see if it is one of those models. Oh, a bent flywheel key and or a vaccum leak which will make it run lean can do this too.
 
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Tom W

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May 19, 2024
Messages
9
So following some pointers where to start digging. This morning i started chasing wires from the harness to the sensors and coil. i tested the coil-good. I found some wires in the cab that were chewed by a mouse fixed that. I tested voltage regulater all good. I pulled the coil off because it sat down inside the engine cover a bit and just wanted to inspect it. thats when i FOUND it. the low oil pressure switch. long story short I disconnected it and it runs good now. I was about ready to add a gallon of gas over the top of it and roast some marshmellows.

that all said I learned a lot about the wiring and engine components. Cold Old Style going down pretty dang smooth right now. I want to thank you all for the pointers hopefully I can return the favor some day.
 

[email protected]

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Jan 27, 2024
Messages
36
Thank You that is another avenue to check into.
I have the 1818 same eng. Same issue but a bit different. Mine would just Stall out I then could restart it but would happen when I wanted to use it. So what I ended up doing was I put an electric fuel pump on it. Solved that issue. As one person said it could be the carb float, Low oil shut off on air cooled engines etc. But the fact was it was not drawing the fuel and to get to that is a not so fun job. Good luck If you still have not found the issue.
 
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Tom W

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May 19, 2024
Messages
9
Too funny-I had the same stalling issue when I first got it 2 years ago. The fuel line ran from the bottom of the tank to the top of the motor about a 2ft run. The rubber gas line had to make essentially a 90 deg turn to hook to the top of the fuel pump. It would only stall once it was good and warmed up. I put a 90 deg fitting at the top of the pump and secured the line better. that solved it. What I figured was the once the rubber line had gotten warm enough it pinched itself off cuasing the stalling. Made sense because the line was old.

Fast forward to the current mess I had with it cutting out- bypassing the low oil psi sensor did the trick. For those with this model you have to remove the coil to see it. I need to hook up another oil psi gauge and sensor but its running good now. fun machine and very useful. All frustrating to say the least.

I hope if others with this make and model read this thread that it is helpfull to them. thanks for the contributions.
 

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