Losing power under load

[troycat]

Mowing with my 1940 9N Front Mount, going through tall grass the motor seems to pop or sputter like its running out of gas, when I get through or lift the deck the rpm"s come up and sounds fine. Checked for fuel flow at carb, seemed good. New TSC Coil & points a year ago. Tractor had been running good. Thanks for any suggestions!

 

[Bruce (VA)]

6v or 12v?

" Checked for fuel flow at carb" How? At the fuel line or by removing the bolt on the carb bowl?

There are ways to check for spark & fuel that work & ways that don't. For example, having gas to the carb is nice, but having it past the float is what counts! That’s why removing the bolt in the bottom of the carb is the way to do it. And, same thing w/ spark at the plugs. Some folks think that checking for spark means pulling a plug wire off & looking for one. Well, it's the distance the spark jumps at the plug that gives you the info you want. It takes about 17kv to jump a 3/16" gap & 22kv to jump ¼” in the open air, so that's why you need to use a spark plug. Or, a store bought plug checker. Remember, it’s 14psi outside of the engine & about 90psi at a 6:1 compression ratio in the cylinders & compressed air creates electrical resistance, so you really need the 17-22kv to fire the plugs when the engine is running.

" New TSC Coil & points a year ago."

I wouldn't be the least bit surprised if the rubbing block on those points was worn out. Quality parts are critical to longevity. Having learned the hard way, I most always use Blue Streak brand points. They are made by Standard parts & available at many auto parts stores. (frontmount points also fit a 48 Ford as I recall) Beware of sticker shock: $16-18 a set. My next choices are Wells or Echlin. Look for a brown rubbing block. Unfortunately, many folks have experienced problems w/ points made by Tisco, Sparex, A&I Products and any TSC ignition parts..
50 Tips

 

[troycat]

Still A 6 volt system, I did check for fuel at the line, I will check at the bottom of carb tonight and check the spark. I wouldn't be suprized either if the points are bad already. Any idea how to seal the breather tube at the engine block? Thanks!

 

[R Geiger]

(quoted from post at 02:58:57 06/04/11) Mowing with my 1940 9N Front Mount, going through tall grass the motor seems to pop or sputter like its running out of gas, when I get through or lift the deck the rpm"s come up and sounds fine. Checked for fuel flow at carb, seemed good. New TSC Coil & points a year ago. Tractor had been running good. Thanks for any suggestions!

If what Bruces says checks out ok, might want to take a look at the plugs. It will run real good on 3 just no power. Might have one fouled.

 

[Bruce (VA)]

"Any idea how to seal the breather tube at the engine block? "

Why? Because it's smoking? Or is it broken & leaking oil?
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[troycat]

Both actually

 

[Bruce (VA)]

If it's leaking oil, seal it w/ JB Weld. But, if it's smoking, that's called 'blow-by' which comes from bad rings. You do not want to stop the breather from smoking. That's why it's there.
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[souNdguy]

popping ( popcorn.. etc.. ) and low power under load could both be symptoms of a lean condition.

try tugging on choke to see what that does. if it helps.. try enriching mainjet a bit and retest a few times... as long as it don't smoke black/sooty out the tail pipe.. etc..


soundguy

 

[troycat]

Fuel flow is fine, Mowed for a short while last night and tractor ran good. So something with the spark. I'm going to get some of those fancy points you guys talk about (although the places I was at last night would have to order them in) and some new plugs. Thanks guys for all the help, wealth of knowledge & experience on this site. God Bless!