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1976 PK losing power when I mow


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#16 classic ONLINE  

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Posted September 03, 2016 - 10:29 AM

Also, that clean spot on top of the piston is a sign of worn rings. That engine looks like it's due for a rebuild. The cylinder is most likely worn egg shaped, typical of Kohlers.

#17 todapuckett OFFLINE  

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Posted September 03, 2016 - 02:02 PM

MNGB-  It loses power, sputters, governor is chasing,  bogs down, and quits.  It will usually crank right back up, but has no power.  I limp it back to the garage and try something new.  I first thought it was overheating, since it is summer in NC, but that isn't it.  Then thought fuel pump/carb issue, rebuilt both with no improvement.  

 

Classic- Thanks, it cleaned up nicely.  Replaced head gasket after trueing everything up.  If I can get it running and get some work out of it this fall, I plan on taking it back down over the winter and doing a rebuild.

 

I will update once I get everything put back together


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#18 MNGB ONLINE  

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Posted September 03, 2016 - 04:54 PM

Hi, it sounds like its running lean at full power, try adjusting the main jet located on the bottom of the carb (float bowl) turn it out to enrichen turn it 1/8th at a time, when its to rich it will start slowing down and will smoke black then go back in 1/2 the amount, Also check the throttle shaft if you have any movement (side to side) you will never get it to run run right its then time for a new carb there are aftermarket carbs on e bay the work as good as any and they are less money the a new throttle shaft and bushing will cost. I have installed at least 4 of the aftermarket carbs and they are all working great.

http://www.ebay.com/...=STRK:MEBIDX:IT


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#19 todapuckett OFFLINE  

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Posted September 05, 2016 - 04:28 PM

Thanks for all the input!  Now I need you all to put on your thinking caps.

 

The original problem was it losing power after a fairly short period of mowing.  After roughly an hour I gave up "tweaking" the carb and playing with the choke and thought it was overheating or something else.   So, you have seen the list of things I have done, I got it all back together and took it out to the pasture this morning.  I made the first lap and it started sputtering and running bad.  I realized that I was on a slope with the front left being the lowest point so I thought maybe the fuel was not getting to the drain valve and it was running out of gas. It had about a 1/4 to 1/2 tank.  Whenever it had cut out before, I would roll to level so I wouldn't run over myself while working on it, so it always "had" gas.  Filled the tank and it ran great!

 

Now, here is the "new" problem.  As long as the tank in FULL it runs great.  As soon as the level drops about an inch in the tank, it runs like crap, I have to full choke to get back to the fuel can.  I fill it up and it runs great for about an inch of gas. I even filled it without cutting it off just to see what happened, full = smooth running.

 

IDEAS?



#20 MNGB ONLINE  

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Posted September 05, 2016 - 09:26 PM

If its really a fuel flow problem then check the filter, tank filler cap vent and I know you said replaced the fuel pump but maybe its not working if all that is as it should be then I'd check the ignition system the Kohler's breakerless system had its problems.



#21 todapuckett OFFLINE  

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Posted September 06, 2016 - 08:38 AM

Filter is clean and cap is venting.  I thought about the ignition system possibly overheating and cooling during the time it took to top off the tank, but I left it running to check that theory and it sure enough it cleared up when I topped the tank.

 

I am leaning towards vapor lock, and the extra fuel is enough to keep it pushing through



#22 shorty ONLINE  

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Posted September 06, 2016 - 08:50 AM

In the tank, is your fuel pickup topside or bottom?

#23 todapuckett OFFLINE  

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Posted September 06, 2016 - 09:16 AM

Drain valve in bottom of tank.



#24 tater195 ONLINE  

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Posted September 06, 2016 - 10:34 AM

You say the cap is venting, how did you check that? Some think the gas cap not venting is an "urban legend" but i have ran across several that do exactly what you are describing and were fixed by replacing the cap. If it does not replace the air to compensate for fuel removed from the tank by the fuel pump, it will create a vacuum that the fuel pump cant over come. The flip side of that is when the gas expands and pressurizes the tank and floods the carb. The next time it does this, dont limp it back to the shop, loosen the cap and see if that helps.



#25 todapuckett OFFLINE  

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Posted September 06, 2016 - 07:09 PM

there is a hole in the cap I can see through, it where the quantity indicator needle passes through and the plastic dome is not installed.  I do need to replace it, the float looks like it is ready to fall apart and cause all kinds of problems, so hopefully that will fix it. 



#26 MNGB ONLINE  

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Posted September 06, 2016 - 08:51 PM

Hi here's what I'd try do as you did before bypass the fuel pump and run it on gravity feed it should be able to run do to 1/2 maybe 1/4 tank, I know you put a kit in the pump but I'd try it.


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#27 shorty ONLINE  

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Posted September 07, 2016 - 05:23 AM

Drain valve in bottom of tank.

That takes out my thought of a bad pickup tube in the tank.
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#28 Alc ONLINE  

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Posted September 07, 2016 - 05:31 AM

 

That takes out my thought of a bad pickup tube in the tank.

I was thinking maybe check the fuel flow right at the outlet just in case it's partially plugged and maybe  the extra gas gives it more head pressure ?  There might even be a screen  on the inside of the fuel shut off . Myself I would start at the tank and make sure there was good flow every place I could check ,right to the pump and if so like what was suggested run it without the pump to test .


Edited by Alc, September 07, 2016 - 05:48 AM.

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#29 esbbent OFFLINE  

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Posted September 07, 2016 - 09:02 AM

When you rebuilt the carb did you check or adjust the float per the specs in the Kohler manual? My MF14 (K321) was acting similar this past Saturday, I pulled the carb off and could see the float was not set right. I followed the book on float level and float drop, put carb back on and ran with no issues.


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#30 todapuckett OFFLINE  

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Posted September 07, 2016 - 09:24 PM

esbbent- Yes, checked the float, it was level and the gap between it and the housing was within specs.  Glad you got yours running again and thanks for the input






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