53 Jubilee Runs Rough Sometimes

I tried to search for an answer to this but I can't find anything that matches my problem. Sorry for the long post.

Background: I have a 1953 Jubilee that I bought from my grandfather three years ago now. It is still 6V. I only use it for mowing our 1 Acre field once a week with a bush hog. It takes about 45 minutes to mow the field. Finding that my grandfather hadn't done much maintenance in the last few years, I changed the oil and did a tune up a little over a year ago. This included a new rotor, cap, points, condenser, plugs (437), and wires. I also drained the fuel, cleaned the three fuel filters, and checked the tank (it was spotless inside from what I could see and all three filters looked clean). I also had the carb rebuilt because the float wasn't working. I am generally good at doing mechanical work but don't have a ton of experience so I do the "easy" things myself. So I think I did all these things correctly since it all ran well for a year.

The problem: As I said, the tractor seemed to run fine for the past year. Just recently it started to occasionally run rough. It would stutter and almost stall. Pushing the clutch in keeps it from stalling but it still runs rough. Sometimes it would do it once and not repeat. Other times it would keep doing it. It would never stall but would get really rough. It would sometimes do it just after startup, other times while mowing for a while. Sometimes both. Sometimes it clears up before I even have a chance to put the clutch in and doesn't come back, other times it gets so bad I can't let the clutch out or it stalls. Basically, it seems random.

What I have tried: I pulled off the air intake to the carb in case the filter was clogged. It still ran rough. I sprayed carb cleaner in the intake while it was running rough and it still ran rough. So I think I ruled out air and fuel as the issues. So I tried spark. Pulled all four plugs and could see spark. Checked the point gap and it was still fine.

Any suggestions for next steps?
Thanks in advance.

What happens if you try to choke it?? If it runs better then maybe some junk in the carb or poor spark.
When it does the problem check spark. It needs to be a blue/white in color and jump a 1/4 inch gap or more.
Next pull the carb drain plug and make sure you have a good steady flow of gas. Catch the gas to look for dirt/rust/water in the gas.
Post back what you find

When I try choking it there isn't any change. I have tried pulling the choke out to various amounts and it continues to run rough.

I pulled the carb drain plug and gas seems to come out in a steady stream (I have no basis for comparison but the flow seemed pretty steady to me, not sure if the volume was correct though it did seem pretty heavy.) Since the carb drain dumps right on the oil filter I really could not tell if what was coming out was clean, so I disconnected the fuel line going into the carb and checked that flow. It was steady and appeared clean. I cleaned the carb screen while I was there. There was one or two flakes of something in there but it wasn't clogged. Up until this problem started happening I had an inline filter on the fuel line. Having read that this is not good for these gravity fed tractors I removed it and put in a new fuel line. This had no impact on the problem. So the problem was occurring with and without a fuel filter.

When I checked the spark, it was with the engine off so I don't know if it was actively having the problem. The spark was jumping the spark plug gap when I touched it to the engine and it was blue but that wasn't a 1/4 inch gap. I will have to get one of the old spark plugs I took out last year and open it up and check the spark over a 1/4 inch gap. I will try to do that tonight.

Thanks for the help.

So I pulled the #4 plug wire and hooked it to a spark plug and put it against the engine. It sparked but it didn't seem very strong. I then did the same to #3 and it looked the same. BUT it also didn't spark a couple time as I cranked the engine. So I moved to #2 and the spark was so strong that it was sparking over a half inch from the engine. The spark then faded as I continued to crank, it then got stronger again. Moving to #1 it was like #3 and #4 but also varied in strength but also did not spark a couple times. So I tried each one again just to make sure of what I was seeing. All four had variable spark strength and sometimes did not spark at all. #2 was the only one that was so strong sometimes that it would spark longer distances. They all sparked more often than not.

This would seem to explain why I am running rough, but what would cause this?

Thanks.

Clean and regap your points. Check the gap on all four lobes
of the distributor and make sure your distributor shaft doesn't
wobble side to side when you press on it. Also, is your spring
clip still under the rotor keeping it tight to the shaft?

I checked the point gap and it was good but did not check all 4 lobes. I did not clean them either but will run a file through them tomorrow night and also check the gap on each lobe.

The shaft does not wobble at all.

The spring clip is still there and the spring itself is tight on the shaft but the cover it keeps in place is not tight and is a little loose. I will have to check how tight the rotor is on top of it. I believe it was tight but wasn't really focused on it. I do remember that when I had the cap off I also noticed that the rotor edge had contacted all four studs in the cap that go out to the plug wires. It had worn them down a little. I had no idea whether that is normal or not. I did clean off the end of the rotor since it seemed to have some carbon on it but otherwise left it alone.

I will report back tomorrow night.

Thanks.

with your trouble-shooting so far, I agree
your points are dirty or junk or the 'new' condensor is junk.(new doesn't rule out 'junk' nowadays)
When you are in there, check all connections and grounds/clamps.
clean......rust and nasties not allowed.

other possible culprits,
failing ignition switch
the insulator going thru the side of the distributor is failing
or rust-bridge arcing randomly.

side question..when you drained the bowl to check flow,
on the restart, did it clear up...even for a short time?
had one once with your symptoms...had some water in the gas.
draining the bowl cleared the water...until it built up in the bowl again.

ps after you get the ignition nailed down..the comment of finding a couple flakes in a screen.....
not what you want to hear...but it only takes one making it into the carb......to turn your purring tractor into a belching, stuttering mess

I prefer to use electric contact cleaner and/or a piece of
heavy paper (paper bag) to clean them. A file can damage
the coating on the contacts.

The cover under the rotor and over the points is a dust cover.
It has to be rotated just right to set down in a groove. It in turn
orients the distributor cap so it points the right way and the
two exterior spring clips hold them both snugly in place.

The rotor shouldn't actually contact the terminals in the cap.
If the shaft isn't wobbling to allow that and the cap/dust cover
were on right, maybe the rotor or cap wasn't made quite right.

Another thought, have you tried hot wiring it to eliminate the
ignition switch as the cause? They have been known to fail.

(quoted from post at 04:39:21 08/12/15)
side question..when you drained the bowl to check flow,
on the restart, did it clear up...even for a short time?
had one once with your symptoms...had some water in the gas.
draining the bowl cleared the water...until it built up in the bowl again.

Click to expand...

Actually, yes, it did. The first time I emptied the bowl the tractor ran great for the entire time I mowed that day. It started to run rough the next time I started to mow so I tried emptying the bowl again. This time it it ran fine for a couple minutes and then started to run rough again by the time I made it out to the field. I was able to mow the whole field but it occasionally ran rough and I would have to clutch it to keep it running. Since it didn't clear the problem up completely I thought emptying the bowl and it running better had just been a coincidence since it will occasionally go through times where it runs great.

I am not sure how it would get water in the gas. The tractor is kept in barn and hasn't seen rain touch it in at least 3 years. My Lawn Mower (2005 John Deere) uses the same gas from the same cans and it has been running fine with no issues. Would it be able to handle the water but the Jubilee not be able to handle it? Would I see water in the bowl if this was an issue?

Thanks.

(reply to post at 04:48:46 08/12/15) The rotor shouldn't actually contact the terminals in the cap.
If the shaft isn't wobbling to allow that and the cap/dust cover
were on right, maybe the rotor or cap wasn't made quite right.

Click to expand...

Thanks Royce. I will try the paper bag.
I used the tune up kit from Tractor Supply and just assumed it would be a good fit since all the parts were together. The rotor has definitely contacted the studs in the cover, I can see the grooves. I will check how much play it has tonight.

Thanks.

So I had limited time last night but here is what I did do:

Pulled the cap off the distributor. Confirmed that the rotor had grooved the copper posts in the cap. Noticed copper dust from the rotor/post contact in the cap and on the dust cover (i.e. copper dust coating the entire inside of the cap). Rotor was a little loose on the post but not a ton and not "wobbly". The spring is there and tight on the post but maybe it needs bent some to tighten up the rotor. In comparing the parts present to the parts diagram online, I notice I am missing two washers that go between the spring and the dust cover. I pulled out the old rotor that I replaced last year (I kept all the old parts) and it had approximately the same fit. I tried pushing on the shaft and it seemed pretty solid. There was a very little bit of movement if I pushed on it firmly but no movement at all if I just gently pushed on it (not sure if that makes sense, but it seemed like the normal amount of play you would have in any set of mechanical components. If it is supposed to be rock solid under any amount of force, it isn't.) I then cleaned the points using a piece of brown paper bag. I checked the gap at all four lobes and they were all .025-.026. Two were tighter than the other two but that could have just been landing at slightly different spots on the lobes. I checked all connections and everything seemed good.

So I put it all back together and checked the spark. The spark at each wire was more consistent than yesterday. No skipping of a cycle like it had yesterday. The spark still wasn't bright blue and arcing over a 1/4 inch. It was sometimes, but most of the time I had to have the dummy plug right on the engine and the spark was blue/yellow and "fuzzy" rather than bright blue and "clean" like a lightning bolt.

So I tried starting it and it wouldn't start. I smelled gas pretty strongly so I think it may have flooded while I was doing all the gap checks. (I had the fuel valve turned off but I think what was in the line drained into the carb while pressing the start button so many times to turn the lobes.). At this point I was running out of time so rather than dry all the spark plugs, I checked the fuel system again as had been suggested.

I checked the bowl and did not notice any water. There was a large bubble of air just under the screen. It probably covered half the screen. No idea if it extended above the screen. If it did, the fuel line would be pulling air rather than fuel. This bowl has never leaked and there are no leaks in the fuel system so I don't know where this air bubble would come from. I emptied the bowl and the gas seemed clean. No debris on the screen. I started to put it back together but broke the gasket as I was putting it back in. So I need to get a new one. I moved to the carb. I pulled the carb screen to check for clogs. Sure enough, there were fairly large red paint chunks in there but not enough to clog it. My guess is they got in there when I replaced the old fuel line with the new one (the old line was painted red and removing the inline filter probably knocked some paint into the line. I had the problem before this back when I know the filter was clean so I don't think this was the problem). So I got that put back together.

I couldn't try starting again due to the lack of a gasket not allowing me to put the bowl back together. I won't have time to get back to it until probably Sunday. The weak spark and bubble in the fuel bowl are both concerning me but I will have to get back to them in a few days.

Thanks.

So I was able to get back to it today. Put the gasket on the fuel bowl and fired it up. It ran great and hen died. Started back up under choke and then would have died but I kept choking it to keep it running. Fuel was very inconsistent. It would flow and then stop, flow and stop. Almost like air was needing to flow back up the line. So I opened the fuel cap and that didn't help. Noticed the fuel went up hill in one spot so I bent the fuel line down. That fixed it (my fuel was low so there wasn't much pressure to force it down the line when it was heading up hill i my guess). So I got it restarted and it still was running rough but it was consistent this time. Spark was good and air was good. So I used the myfordtractors.com carburetor tuning guidance and worked on the carb. I found my carb was WAY out from the starting point they recommend and was probably running very rich. it was also set to idle at around 1200 rpm. So after doing the adjustments per the web site, I was able to get it down to idling at around 500rpm and running pretty smooth (other than some sort of exhaust noise that i will deal with later).

I mowed the whole field and had no issues. I will see how it does over the next couple of weeks but I am guessing it was just a misadjusted carb, coupled with low fuel in the tank, a bent fuel line, and weak spark. All that combined to make it run rough. I hope.

Thanks to everyone for their help.

Glad to hear you got it running.
What did you find out with the rotor hitting the cap?

I never did anything with it (the rotor/cap interference). I am assuming that the parts I got from tractor supply weren't of the greatest quality and had bad tolerances causing them to hit. Now that the rotor has already worn down the cap, I am hoping they have settled in.

It could be that I don't have the two washers that go under the rotor. They cost $12 each through New Holland and I don't see them offered on this site. Instead, I ordered a new dust cover from here and I will see if that tightens up the tolerances to keep the rotor from jiggling around the little bit that it does just in case that was a contributing factor.