Engine Used to run but won't start now " 8hp 32" lawn tractor with electric start

[bobthewoodbutcher]

For starters , my SEARS model number is 536.255113 (it only says Craftsman on the cover page all other references are SEARS)
the engine is Tecumseh

i have the complete old manual but It does not reference an age. The local mower shop says it could be a 1960's model
It ran when i bought it although it was hard to start.
I used it throughout the summer after I finally got the blade height to my satisfaction. no more than 6-8 times

It seemed to use a lot of fuel so I figured I would "tune it up" Big mistake!

After reading the manual I got it running, with the manual settings on the carb, but rough and poorly. this involved a new J8 plug to replace the one that was in there( no idea what the old one was.)

the next time it would not start. 2 or 3 pops and nothing I twiddled with the mixtures but nothing.

My friend is a Mercedes mechanic who started out with B& S small motor training. He came over and rebuilt the Carb
Hard start but after lots of stalling and adjusting he got it running and set the idle, etc so it would run at all speeds, idle etc. He had used up his available time and said to run it tomorrow and he would be back to tweak it.

I has not run since. lots of cranking not even a pop. i got it to run on starter fuel once or twice but only for a few seconds

here is what i tried. I used his settings and cranked it swinging the throttle through choke to idle and back again repeatedly like he did to get it to start originally

did the same with factory settings

removed the rubber cover from the plug and held the wire near the muffler and had spark but when i put the wire back on the plug and grounded the plug against the muffler I could not detect a spark

changed the plug to the old one. Same as above but there might have been a weak spark but I might have only imagined (wished) it

Re assembled everything , cranked it. nothing, sprayed starter fluid lightly near the carb throat ( filter removed) not a pop. more starter fluid , nothing. Waiting for my friend to be free

I have fresh fuel, obviously air and at least an occasional spark. Why can't i get an occasional pop?
common sense says I do not have a spark.

I'm totally stumped

It least I have my walk behind

 

[ILENGINE]

Re: Used to run but won't start now " 8hp 32" lawn tractor with electric start

Does sound like a spark issue. Can you get us the model number off of the engine tag. Should start with 143

 

[bobthewoodbutcher]

Re: Used to run but won't start now " 8hp 32" lawn tractor with electric start

sorry it took me so long
the engine model is 143-286122 serial # 8012R
this morning after jacking the throttle from choke to idle. back and forth about 4 times i did get a single pop. nothing after that.
going to get a new J8 plug

 

[bobthewoodbutcher]

Re: Used to run but won't start now " 8hp 32" lawn tractor with electric start

I tried this today and I think I am getting closer
I f I almost ground the spark plug wire I get a spark.
If I connect the spark plug and ground the threads i get no spark. conclusion: my spark is too weak to jump the gap
I bought a spark plug spark tester and performed the above test with the same results.
My friend did not like the new j8 champion plug I bought at Home Depot in the mower parts dept because the tip was extending above the threads.
I bought a new champion J8 at the auto parts store and the tip was flush with the threads It was listed as a small motors plug

The manual said to set the gap at 0.030 which is where I have been setting all the previous plugs.
Since I was not jumping the gap at .030 I reduced the gap in the new one to 0.025 but the gap was tight so i guess I am a little less than that.
now I get a consistent spark but only a few pops. My friend is coming soon to tweak the carb


Will running the mower with that small of a gap present any problems?

wish me luck

 

[bertsmobile1]

Re: Used to run but won't start now " 8hp 32" lawn tractor with electric start

That tells me either the coil is dieing has a bad ground contact of if this a points and condenser engine the condenser is bad.

 

[bobthewoodbutcher]

Re: Used to run but won't start now " 8hp 32" lawn tractor with electric start

the parts list indicates it is a magneto but I see a condenser and a contact breaker in the parts list
I did not know that a magneto used contacts. now I do not know what I have.

I removed the nut that removes the fan screen and there is a large washer under the fan screen.

Under the washer is a white plastic part with 4 protrusions that key into notches in the fan/blower. I am hesitant to go further because I am afraid of messing up any timing
i did not see a flywheel key but I think that is because I have no gone far enough.
i have attached 2 pages from the manual



I seems that everything I have done so far has created a chain of new problems

I started with everything running fine, just a little rough and eating a lot of gas.

I tried to adjust the carb from the manual which resulted in the engine not starting
then my friend decided to rebuild the Carb which has now exposed a weak spark and the engine wont start

please help if possible

 

[bertsmobile1]

Re: Used to run but won't start now " 8hp 32" lawn tractor with electric start

bob.
A magneto consists of a power generating section and a timing section
The power bit is the coil and magnets.
The timing bit was originally points and a cam with a condenser ( capacitor to some )
In 1961 some clever sods ( in Australia ) invented a system that eliminated the points, called a "Hall Effect Trigger " which eliminated the points.
Up untill the patient ran out they were a stand alone section connected to the magneto coil.
After patient ran out they were incorperated into the coil unit and the price quadrupled.

So some older engines still have points, some latter ones have points eliminators ( can be retro fitted to old points engines ) while the modern ones have an "ignition module" which is the coil and trigger combined.

As you said it was an older engine I assumed it still had points fitted.

 

[Boudreaux In Eunice La.]

Re: Used to run but won't start now " 8hp 32" lawn tractor with electric start

I really don't care for the Tecumseh engines for a couple reasons. They are good engines though. Me and a friend of mine had a Briggs shop and parts were cheaper for those. Also easier to get. Then I met a girl when I was single at the time and she had a Craftsman rider mower with the same engine you got. It would run on half choke only most of the time. There was a mosquito hawk inside the gas tank. I tried to get it out with some long needle nose pliers and one of the legs broke off.

No filter on the gas fuel line. I rebuilt that carb and same thing. I tore that carb apart 2 times before I finally took the seat out of the carb. Lo and behold there was that dang mosquito leg in the hole under where the seat sets at. I soaked that carb 2 times in acid and that leg did not go away. Tough stuff...........

When I got it right I put a fuel filter on it. Also I got a brand new Craftsman tool box in the deal, A roll around bottom and top set for my time trouble for other work also that I did...

You can replace that system you have with a regular new style Mag coil and do away with the points. Just do away with the wire that goes to the points under the cover.........

 

[bobthewoodbutcher]

Re: Used to run but won't start now " 8hp 32" lawn tractor with electric start

Well, I am back. Still not running. We got it to run twice since my last post but the next day nothing. the carb has been rebuilt ,twice. points and condenser/capacitor replaced. points set at .020 after much discussion

I now have a coil on order. Spark tester shows an occasional spark but nothing consistent.
I am getting pretty good at removing the flywheel. the first time was a bear but I was surprised that the second , third and fourth was almost as difficult. I discoverer by accident that if i loosened the nut and hit the starter; the centrifugal force will spin the flywheel up the tapered shaft. do not loosen it too much or you can lose the woodruff key.

thanks for all your ideas. So far I think ( hope) I am getting closer. there is not much left to change. I will probably never be Bob the mechanic

bob the woodbutcher

 

[EngineMan]

Re: Used to run but won't start now " 8hp 32" lawn tractor with electric start

When you get the new coil it should give a nice blue spark when the air gap is set up right. it seems you going by the book, but you don't have one let me know.