engine boggs down when pto engaged

[Anonymous-0]

hi guys,

i have a 1956 massey harris 50. i has a rebuilt engine, alternator, and i recently put in electronic ignition. i was running a bush hog and it ran fine for a while, then the thing started to miss and bogg down when the pto was engaged. i could get it going, but as soon as it was under any load it bogged down and stalled. runs fine when pto isn't engaged. could it be the ignition or coil? i'm no mechanic, and i'm getting tempted to go buy a new kubota...but i like this old tractor. thanks for any help you can give me.

chris

 

[JIMCO]

I have a 33 and i was baling hay and i had the same problem. I put another coil on it and ran fine.

 

[Jerry/MT]

The coil doesn"t know anything about the pto.

When the pto is engaged, is there some external load on the hitch or the pto? Were you "hogging at the time this occured? How big is the "hog?

When this happens again, quickly shutdown, pull the centerwire out of the distributor cap, hold it near a good ground and try to start. You should see a FAT, BLUISH-WHITE SPARK the color of lightning. If you don"t, your problem is in the ignition system, most likely the primary circuit. Since you have an electronic ignition, the points aren"t the problem so lets assume that te elevtronic ignition is running correctly, for the moment.

Is you electrical system 6V or 12V? If it"s 12v do you have the correct coil for a 12V like NAPA IC-14SB(~$15) or was the 6 V coil retained and a resistor put in series with the coil to limit the current? If you have a 6v coil without the reistor you could have a coil overheat problem. Check all the connections and make sure they are clean and tight. If the sick spark still exists, put a jumper across the key switch to eliminate it from the circuit. If that clears the problem, replace the switch. Make sure that your battery is fully charged. If all these things check out , I"d start to suspect the elctronic ignition.

Let say you have the requisite FAT, BLUISH-WHITE SPARK. Then you need to check the timing and the advance. For that you need a timing light. If the timing is off, reset it and try to work it again to see if the condition clears. While your checking the timing, see if the advance works by reving the engine and watching the spark advance with the timing light.

If you have the correct spark, timing and the advance is working, you need to check the fuel delivery. If your carb has a drain plug on the fuel bowl, get a container, open the tank valve, and hold the container under the carb and reove the plug. The fuel should CONTINUOUSLY GUSH OUT like a cow peein" on a flat rock. If it dribbles or is intermittent, the fuel deliery is restricted. Check the tank vent( usually the cap is vented), the filters in the sediment bowl, sometimes there is a screen in the fuel inlet elbow on the carb. Look for a kinked fuel line. Until you have an adequate fuel supply, you won"t develop max power. Is your carb adjusted properly, especially the power jet? When the engine bogs down, does choking help it? If so your mixture could be too lean because of a misadjustment or an air leak downstream of the carb metering section. Leaky thottle shaft seals, leaky gasket between carb and manifold or leaky at the cylinder head intake manifold connections or a crack in the manifold itself.

Make all these checks systematically , checking the operation of the engine after you make any change. Record the results in writing so you don"t forget and can analyze the reults latter. Since the engine needs good spark at the right time and the cylinder needs to be charged with the correct ammount of fuel and air, when you get these three things right, the engine will be running correctly.

 

[JIMCO]

When the coil is weak and engine is under heavy load,it doesn't have enough electrical current going to the plugs.Tractor doesn't have power,misses and shuts down. That is the way my 33 did,until i took the coil off of my 44 and tried it and worked fine.A new coil costs about $40.00.If you have another gas tractor in the same horse power class try that one first before you buy a new one.

 

[Anonymous-0]

thanks guys...

 

[Laurence Lombard]

I"m afraid to say that I cannot add much to this thread except to say I get the distinct impression that Jerry/MT has attended to more than just a few sickly spark ignition engines in his day. Now I need remove from my imagination the image of the Fat Bluish-White Spark (like lightning) and the Cow Peeing on a Flat Rock!

 

[Jerry/MT]

These metaphors help people remember what to do when their engines don"t run well. It caught your attention, didn"t it?

In my professional carrer, I found a little humor always helped the situation, also.

 

[Anonymous-0]

well thanks again guys. it was the coil. put a new one in and i'm back in business.