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318 bogging down on inclines when pto engaged. help!!!

7400 Views 19 Replies 8 Participants Last post by  D-Dogg
I just mowed for the first time with my new to me 1983 318. It runns great except when mowing up a hill. the engine boggs down and trys to die unless i shut off the pto and then throttle down and then back up again. If i let it idle for a couple of seconds and then fire the pto up again it runs fine until half way up the hill. it has a 20 horse onan so it should have more than enough power for my little hills. I have to think that it is the governor or something in the carb, any ideas? I am very new to this garden tractor stuff but want to learn and see myself being a huge 318 geek before long. LOL
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It sounds like a fuel problem. I am wondering if it has a fuel filter. I would also check the fuel line and and tank and make sure no crud is in there. Also check for watrer in the fuel.
I just ran new fuel lines, with a new filter and put fresh fuel in the tank. the air filter needs to be replaced but I think that it is in the carb. when it boggs down i can smell un burned fuel.
How badly does that air filter need to be replaced?

Will the tractor drive up the hill no problem with the PTO off?

When you changed all the fuel lines did you verify the pickup was clean?

Is the choke partially closed?

Can you do a fuel flow test?

You could try some Seafoam in the tank, but it sounds to me as if either the fuel pump is not delivering sufficient volume, or perhaps the float is sticky.

Seems to me I read a link or two about Onan floats and ethanol causing them to swell.
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Sounds like it could be the carb. One other easy thing to try is spark plugs if you have not changed them..

I had a Honda generator that ran fine until the load got too high and then it quit. Turned out to be a bad plug.
Good point ccsial, I've seen some leaking plug wires too.
it runs fine up hills with the pto off. I just replaced the fuel pump and checked the pick up tube while replaceing the fuel lines. the air cleaner is in bad shape and I bet the spark plugs are old. I will change them and then give it another try. does anyone know how to twll what year an onan engine is. the p220 that is in this 318 looks very new. serial nimber is J 973745824
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J is the 10th letter of the alphabet, so October, and the next two numbers indicate 1997 (if this follows the logic of Onans used in gensets).
Hi carleshicks , :Welcome1:

D-Dogg does these 318's have vacuum hoses ??? Just throwing an idea out
there ...

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You thinking a small enough vacuum leak that the fuel pump is delivering some, but not enough fuel, x595? I assume it's the same setup on the P220.

How did that vacuum line look when you replaced the fuel pump, Carl?
Change the air filter ,it sounds as if it may be "choking" off the amount of air you need ,and install the new plugs,b/c it sounds as if they are fouled from to rich a fuel mixture from a clogged airfilter some carb cleaner in your fuel,and then report back....the only other thing that comes to mind is my 316 will slow dowb going up a grade ....and I know it needs rings as it burns 316 is a 1984 I believe. Good Luck,Jim
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thanks guys I will replace air cleaner and plugs and report back
My best guess is fuel volume while under load. I would go ahead and remove and service/clean your carb, check the jets, and blow out all the orifices b/c based on your story that it hasn't run in a while or mowed recently, perhaps some varnish has built up in the canals of the carb, thus reducing fuel flow. Who knows, but do the easy stuff first like the air filter, plugs, inspect fuel lines, especially the fuel pickup to.

Another thought. How hot is the ole girl running? Check all your fins also, b/c if it ain't breathing/cooling good then that starves HP also. Just check everything on it.:praying:
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I think it's a spark issue. One cylinder not working properly. Make sure both plug wires are on, then test to make sure both are getting spark...
Well I changed the air filter, spark plugs and did an oil change, still doing it. I see that the previous owner installed an extra spring to hold back the throttle at the carb. if I take it off it idles way to high. I am willing to bet that the governor is trying to overcome that spring tension when under load. does anyone have the service manual that can send me the info on adjusting the carb. I have to believe that is where my problem lies.

also the vacume line looked good when I replaced the pump.
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Or you are sucking in air from a leak ???? Jim :thSick:
in the fuel line? or vacume line? I just replaced the fuel lines.
A vacuum leak at either the carb or intake manifold would do it.

You inspected the vacuum line to the fuel pump and made sure it is connected and sealed at both ends.

Next step would to be to check for a leak around the carb and manifold.

Some use a propane torch for this, but if you're not certain your plug wires might not be leaking and arcing, propane might be a little dangerous.

Once your sure of your wires, you can start the engine, and pass an unlit propane torch around the carb and intake, listening for an RPM change. Safety dictates you should do this outside with a partner and a fire extinguisher close by.
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Or spray some carb cleaner around the intake and do the same....
Now this was on a Briggs, but this very evening my neighbor who had been having the same problem came over and asked if I had a spare mixture screw as his seemed to be MIA.
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