Re: Farmall M Runs When Chocked - Need Help

Sparetime

New User
Thanks everyone for the replies and helpful advice. I'll comment on a few posts where I can, but will need to spend some more quality time with the tractor when I have a chance to check out some other suggestions.

[color=blue:90330be1d5][b:90330be1d5]Throttle/throttle plate/governor[/b:90330be1d5][/color:90330be1d5]

- Seems like I'm getting conflicting information on the throttle position. One indicates that the way I described mine working is correct (idle position = farthest from driver / high throttle = closest to driver) which I think is the case based on the governor/throttle plate positions I've described. I could see them being mixed up at the bell crank had I disassembled them, but I have never taken them apart from when the tractor was running fine, so I couldn't have reversed them. I'm currently working on the assumption they are not reversed at this point, but will investigate further.
- I was pretty careful on reassembly of the throttle shaft. Note that I think I forgot to mention that I did not remove the throttle plate from the throttle body. There seemed to be no binding or slop/play in it. Basically, it seemed to be working perfectly fine so I decided to leave it alone. Worth a recheck though!

[color=blue:90330be1d5][b:90330be1d5]Carb - Gas/Air flow[/b:90330be1d5][/color:90330be1d5]

- I still haven't completely ruled out something with the carb. such as a blockage or float problem, but I've sure spent a lot of 1:1 time with this thing so far. It does just seem like it's not getting enough gas, but as several posts have suggested the root cause could lie elsewhere (manifold leak, loss of venturi, points, etc.)
- I initially have set the main jet to 3 turns out during carb. reassembly procedures, but did experiment with turning the screw out probably twice that or a little more when trying to diagnose fuel flow issues. It had no effect at all, which brings me back to blockage/lack of venturi investigating.
- Fuel filter - As noted I seemed to be getting good fuel flow to the carb. and float assembly, although I obviously can't see the float in operation once it's all back together. It has run fine with the current filter in place in the past, but replacing it at this point makes sense. It's cheap and rules out one more potential problem area.
- Carb. fuel inlet filter (the brass screen one that screws into the carb. that the fuel line screws into) was removed and throughly cleaned. I could see daylight clean through the screen once clean. It had some minor buildup, but is clean as can be now.
- Only checked manifold bolts for tightness (all good) and checked condition of carb. gaskets, both of which were in reasonable shape. I replaced them anyway. Further work on this front is warrented at this point.

[color=red:90330be1d5][b:90330be1d5]So, my next steps I believe would be are............(starting with the easiest stuff 1st)[/b:90330be1d5][/color:90330be1d5]

- Check point setting and condition
- Replace fuel filter with gravity fed compatible filter (or maybe remove completely?)
- Test compression on all cylinders
- Test for gasket/manifold leaks (propane/carb. cleaner)
- Inspect bell crank assembly & inspect/reassemble throttle shaft assembly & settings
- Reinspect/clean carb., particularly mian flow pathways? (ack!...not again!! :shock: )

Thanks for any additional comments or advice!
 
I'd still venture to say it's the carb, barring some memorable event such as overheating, removing the intake manifold, etc.
The best advice was checking for the vacuum leak.
I had the same situation of needing ¼ choke to make it run right. After using brake cleaner around the manifold and carb, I noticed an increase in running condition when I sprayed around the throttle shaft.
Also, learn from me that, if you send it in to get rebuilt tell the re-builder you found the throttle shaft area to be problem. I originally sent mine in and when I got it back it ran the same. Sent it in the second time after talking to the re-builder and he replaced it for no cost. Didn't make it right, but wanted to fix it right.
 
All excellant thoughts and suggestions. I think the thing to remember is that the tractor was running fine and then not. So what changed.
My similar experience with an H was crud in the fuel tank.
But we are all missing the main issue. The more important issue here is why is this post scattered all over the forum and not in one post :)
Happy Thanksgiving,
Dell
 

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