Ford 8n - Must Have Choke Out

[blount2000]

A problem has cropped up with my Ford 8N.

I use the tractor primarily for bush hogging, and the tractor ran fine at the end of the season last year (around October). I did not use the tractor any during the winter, but did put fuel stabilizer in the tank when I parked it in the shed. I also went out and cranked it and let it run for about 10 minutes every couple of weeks over the winter, although I did not drive it any.

Now that the bush hogging season has started this year, I have run into a problem. The tractor cranks as easily and quickly as in the past, and will idle and rev up fine when just sitting there, but now it must have the choke pulled out a little bit or it will immediately go dead whenever a load is placed on the engine. I did a little bit of cutting this past weekend, and I had to hold the choke out a little to keep it running. With the choke held out it ran just fine.

I went out at lunch today and let it idle for about 10 minutes to warm up. I sat in the seat, gave it a little throttle, engaged the PTO with the bush hog attached, and as I let out the clutch (the tractor is in neutral) the tractor dies. I cranked it right back up, gave it the same amount of throttle, pulled the choke out about 1/3 of the way, and when I let out the clutch (still in neutral) it did fine and the PTO spun the bush hog right up without any problem at all.

I don't have a problem holding the choke out a little, but I've been told this can make the engine run hot and damage things.

I've tried a couple of things (see below), but don't want to just start throwing parts at it. From what I can see, the next proposed step may be to do a carb rebuild kit (unless advised otherwise). I'm not super mechanically inclined, but I do have a manual and have viewed some online videos of how to do the carb rebuilt kit and I think I can do it successfully.


Anyway, could this be anything other than a fuel delivery issue?

Thanks!



Other Info:

8N (not sure what year)
6V with front mount distributor
Fuel bowl was quite clean
Removed & cleaned fuel screen at bowl
Removed & cleaned fuel screen at carb
Have vented gas cap
Fuel bowl remains full of gas when running
Pulled plug out at bottom of carb, turned on fuel knob, and fuel runs freely out of bottom hole
Carb adjustment screw setting not changed since last year when running fine

 

[grainger12002]

try to clean out the main jet first, i think its the bottom one,but take the top off and look down you will see a jet,unscrew it,run a fine wire thru the center to assure its clean and free of obstruction and try it, also be sure you have good fuel flow from tank-may be able to access by inserting a flat screwdriver form the plug at bottom ....

 

[Baby Grand]

Sounds like either you're not getting enough fuel (check/clear the jets, as grainger suggest) or you may be getting too much air (leak between the carb and the cylinders) causing it to run lean.

 

[Jerry/MT]

Having to run with a the choke partially closed can be caused by a weak spark or too lean fuel/air ratio.

Since I assume non of your carb settings were changed , a lean mixture can be cause by an air leak around the carb's metering section. The usual culprits are worn throttle shaft/ seals, leak at the carb to manifold interface, rust hole or crack in the intake manifold and a bad manifold gasket at the block. The carb may also be dirty, especially the transition port that is above the idle port on the carb. This supplies fuel for operation just off idle before the main jet begins to provide significant ammounts of fuel.

A weak spark can cause this problem also and it's not uncommon for engines not run ofthen to have corroded oily and dirty points and also the advance weights can stick causing the timing to be retarded at increase rpm, though that is generally not a problem.

I'd check the spark first and make sure that it's good( FAT AND BLUISH-WHITE) and if that's the case then consider checking for leaks around the places I mentioned. CAREFULLY spray starter fluid around the places I mentioned and if the engine speeds up, you found your air leak. If you don't find an air leak remove your carb and give it a good cleaning making sure the transition port is open and the passage clean.

 

[Soundguy]

ditto what jerry said.

she's lean or weka spark.

not ethat lean can be a fuel stoppage too. tank tap.. sediment bulb screen.. elbo screen. bit of crus under a needle.. etc.

ps.. using choke won't make her run hot. letting her run LEAN can certaintly do so..

 

[eddie48]

Why not just open up the main jet screw a quarter turn and see if that fixes the problem before you start taking things apart?

 

[Baby Grand]

Trick:
To find an air leak, spray some carb cleaner on the area in question with the engine at idle.
If RPMs pick up, you've found a leak.

 

[Egon]

Why not just open up the main jet screw a quarter turn and see if that fixes the problem before you start taking things apart?

That's just too easy!

 

[Soundguy]

and it's bad info! or at least incomplete...

you don't open a main needle to fix a dirty carb.

you can simulate enrichment with the choke.. just like opening the main.

if it ran, adjusted the way it is, without choke, then the darn needle just didn't screw in on it own.

easy fixes are rarely the best ones.

to the op. do as you please.

 

[Egon]

What's bad about it. If it works it's pretty quick and easy?

If it only works temporarily then one has a pretty good idea that there is something extra in the fuel and can act accordingly!