105 won't start low compression stale gas what do I do first?
 

Ok, so I really don't know a lot about tractors or engines. I have done some pretty big auto maintenance though like ball joints and rebuilding a Bronco front end, so I think I can learn. I got my choke cable done finally last night and started looking at other things. I can't get it started even with starting fluid. Turns over no problem, but won't start. She has been sitting for 2 months so the gas is probably stale. So I started draining the old gas, took of the sediment bowl and drained at the petcock. I still have to get fresh fuel so I start looking through the service manual and read about a compression test. So I do one. 65-70 psi. Uh oh!! Spark plug is real sooty looking. Where do I start? The Kohler seemed to run well last time it ran. No noticeable smoke or odd noises. Could carbon build up on the head or something else cause low compression, or is it definiyely time for new rings or a possible rebuild? Sorry this is rambling but I get "Cub time" in fits and spurts, so I am trying to take advantage of a few hours this week.

98% of all carburetor problems are electric. First thing, check for spark.

You are going to get a low compression reading because the Kohler motors have a compression relief system built in, otherwise the S/G wouldn't turn the motor over fast enough to get it started.

Don't get me wrong, yes you probably should clean out the fuel system, but the first thing I always do is check for spark. Then work backward from there.

And yes, the carbon should be cleaned out of the combustion chamber at least every couple of years (depending on use) but that probably isn't going to keep the motor from starting right now.

So to check spark, I pull the plug out of the engine and lay it on the block and turn off the lights right? Turn the engine over and look for the spark across the electrode? Then followw it to the coil, then points? Is this in the service manual, or just general knowledge? I am going out right now to check for spark.

What is the procedure for checking spark? Sorry, I am really that uneducated about all this and I want to make sure I am doing things correctly.

I've got a little gadget that I got at Harbor Freight for about 2 bucks that goes in between the plug and the wire, it lights up each time the plug fires. But yeah, remove the plug and ground the end to the motor and turn it over, while looking for spark.

Normally, when I get a new to me old Cub, I check the battery with a test light to see if there is any life in it, if the light burns bright the battery is better than if the light burns dim, not dealing with rocket surgery here... If it's dim or doesn't light at all I unhook the battery and get a boost box and hook up to battery cables. Turn the key to the "run" position, then using the same test light I check to see if there is power to the coil (small lug +) if there is then go to the other side (small lug -) then turn the motor by hand to open and close the points (test light will go on and off as points open and close while touching test light to the neg. side of the coil). Turn the engine till the points close then open and close them with your finger or screwdriver and watch for spark between the contacts of the points. If you have power to the end of the wire where it hooks to the points but no fire between the point contacts then file the points a little and try it again, you will probably want to check the point gap, especially if you have filed them. If you don't get a light at any of these steps then you have to go backward from that point, and you will usually find a bad wire or bad ground.

Some of the guys will argue that you need a volt meter to check volts and resistance and that I don't know what I'm talkin about, but this method has never failed me yet, if you get fire to the points and a decent fire at the plug then this should be good enough to at least get the motor started. After the motor runs then check volts and resistance and replace/repair parts as needed.

One thing that I'm sure the guys will agree with me about is, if you don't get power to the places that you need power to, there are three very important things to do.

Check your grounds, Check your grounds, and Check your grounds.

spark
 

FWIW.
Sometimes a spark plug can short down the center electrode appearing to not have any power getting to it.
If you stick a bolt or screwdriver in the plug wire boot and position it close to say the head, and look for a spark as you crank it over, that will tell you if or not you have spark.
I taught small engines to my 4H kids for a few years, and one time asked them if a engine would run without a carburator? of course they said no!
Wrong I said, and I proceded to remove a carb from an engine.
then I sprinkled a little gas in the intake port with a spray bottle and cranked it over and it ran.
of course it ran as long as I sprayed a little gas in the port.
Yes, the rpm was uncontrolled but the fact remained that the engine continued to run.
3 things are needed:
Air,
fuel,
and ignition, at the right time.
if you approach the problem with those things in mind.
usually it is quite simple to find the problem.

ol'George,

I agree, I think sometimes we unintentionally make things more complicated than they really are.

MrChic-

You might also ohm out the coil wire. I recently had one bad on a tractor and it drove me nuts. I finally decided to ohm it and found it broken. It's not an everyday occurence but it happens.

Wayne

I'd suggest pulling the plug and laying it on the head and spinning it over. If you see spark, dribble a teaspoon of good gasoline down the spark plug hole. Put the plug back in, connect it, and see if it will fire with the choke open and at half throttle. If it fires a couple times and quits, you probalby don't have fuel flow. If it doesn't fire, you might have a weak coil (or plug wire like whystle says) where the compression kills the spark.

I haven't been having much luck with starting fluid lately. Probably someone made it safer by making the stuff less volatile or something. I was trying to start my 126 the other day and after spraying a bit in the carb, I had to spin it over a long time before it fired at all. Even then it was very weak. I seem to remember starting fluid being better than this. Does it get old with time? This was some Napa stuff that is probably more than 5 years old. With real gas, it should always fire at least a couple times.

Good Luck! Your compression doesn't sound that bad since you were probably operating the automatic compression release at starting speeds.

The first thing I would check is the battery. The battery may turn the motor over....it still needs current to fire the spark plug. The starter will hog the most current....sometimes leaving little to no current to fire the spark plug. The age/condiation of the spark plug has plenty to do the spark plug's performace. Best thing to do once a champion plug is fouled is replace it. An Autolite 215 spark plug is a good plug for your Kohler motor. A new points and condensor may needed.

The fuel system-carb, sediment bowl and gas tank may need cleaned out.

Best thing you can do all you small motors is go to a 30 gas rule. Any gas (2 and 4 cycle ) in my storage container that is 30 days old is add to one of my autos. I will add a fuel stablizer to my storage container before I add gas to them. Two good stablizers are Sta-Bil and the one that Briggs and Stratton sells.

I don't used starter fluid. Gumout carb cleaner works great.

Hey all, thanks for all the advice. The battery is new, only a few months. I will charge it tomorrow just to be sure.

I drained most of the gas from the tank through the petcock with the glass bowl off. How do I get all the gas out? It looks like there is a little more in there. Do I need to take the tank off?

When I was fooling with the sediment bowl, I noticed if I tightened it real good and opened the fuel petcock, gas wouldn't flow. If I loosened it, then it would start flowing and leak. There was not alot of gas in the tank at this point. Could this just be because of the gravity feed of the fuel system?

I have a new plug and I will try it. As far as laying the plug on the head. The head is not really accessible, it is covered by the shroud/sheetmetal. Am I trying to ground the plug? Is placement on the engine somwhere critical to do a good spark check?

I maybe headed to the dealer this weekend for new front wheel bearings, so maybe I will pick up a coil and points. Is there anything else needed for a good tuneup? I have a new plug, oil, and air filter. Should I get a new plug wire? What exactly is the condensor?

Sorry for all the questions. I can handle the chassis type stuff much better on my own. Thanks for all the help.

Good idea to charge the battery.

Try taking the whole fuel bowl assembly off of the tank, let it drain and look inside the tank for rust, crud, or what ever. Then take the fuel bowl assembly apart, clean it well and blow through it. If the tank has crud in it you will probably want to take it off and clean it out.

Not sure I understand this part, almost sounds like the vent in the cap is plugged or the tank has crud in it.

Yes, you are trying to ground the plug, placement is not important, as long as it gets ground and doesn't ignite any fuel.

[QUOTE=Merk;15205] The starter will hog the most current....sometimes leaving little to no current to fire the spark plug.



I had that happen to me. I spent a long time going in wrong direction before I figured it out. Bad armature.


And it happened suddenly.


.

Not sure I understand this part, almost sounds like the vent in the cap is plugged or the tank has crud in it.

No the tank, looks nice and clean. Maybe I will get a new gas cap while I am at it.

Probably should pick up a carb kit too. Wow my shopping list is getting long.

:bigthink:

filter bowl
 

If the Carb float bowel is full of gas, the needel valve is seated, or closed if you perfer.
And is basically saying I don't need any more fuel in me.
so you will see no fuel flow to the carb looking through the glass bowel,because the line is closed off by the needle valve. if it can't get out the end, it can't flow.
when you loosen the glass bowel, you are allowing fuel to flow because there is a leak in the system so to speak..
Now if the needle valve is stuck closed in the carb. with or without fuel in it that is a different story.
first and formost see if you are getting spark and we will talk you through it.
Do what you like, but I would not get in a hurry to purchase a coil, condenser, points just yet, lets see what it needs or is wrong, most likely is is something simple. and you are learning "process of elimination".

Many Many times a simple thing like the points having a slight bit of corrosion
or rust will prevent them from working and with a little cleaning all is well.
this is the fun part, finding the problem, not throwing parts at it til it runs.
Growing up in the early '50's we didn't have $$ to spare so we learned to spend only where needed.

ol'George is exactly right...

I used to try to explain to my ex, that throwing money at every problem that comes along is not always the best plan of attack.

ol'George, is also right about the gas flow issue, I never thought about the other end of the hose being attached to the carb, I just figured that it had already been taken off.

And I wouldn't buy a new cap, IH wants about 9 bucks for one, just take yours apart and clean it out, or try blowing through the little hole in it from the outside to see if it's clear.

Ok, my battery is good, my plug wire is good (I checked, no resistance), my tank is clean and flows, but I will check the cap. So I need to check my plug, coil and points. Points I think I got. What is the best way to clean them? Should I steal one of my wife's nail files? Is there a way to test the coil? The ground for the coil is the one connected to the block correct? The one that goes to the starter gen, is that the hot lead? I am going out to get fresh fuel and put some sta-bil in the can first (Thanks Merk) and I really hope I can get this figured out tonight.

The Neg (-) side of the coil goes to the points, that is the same side the condenser is hooked to.

Nail file will work...

If you need to check your coil... http://www.onlycubcadets.net/forum/showthread.php?t=11

spark or not
 

Power to the coil,
There is still a debate as to if the hot wire (usually from the ignition switch) is connected to the plus or minus markings on the coil, and I don't want to get into a debate. it will work both ways.
I prefer to hook it to the + marking on the coil.( some coils are not marked)
The other wire - goes to the points where they are grounded/ungrounded as they close or open, thus completing the circuit, providing ignition or "spark"
While the points are closed, the power is building up in the coil, it does this instantly.
It is when the points open, that the spark occurs, not when they close.
a person can turn on the key, or put a hot lead to the coil + and watch a spark occur at the spark plug by opening or closing the points with your finger, popsicle stick, pencil or anything else non conductive.
Turning the engine over will do the same thing either by hand or using the starter.
This will tell if you are getting spark.
You will at most times see a small spark, at the points, while the points are closing or opening, this is normal.
It is the condensers job to keep this small spark to a minimum, to prevent the points from eroding greatly or prematurely.
The points should have a gap of say .016-.019 ( it varies) when pushed open by the cam and the points need to be clean so they make contact with each other, when closed
yes they can be lightly cleaned with a small nail file. the proper way is to use a diamond dusted point file, but most folks don't have one.
Sometimes something as simple as a piece of paper carefully pulled through the points will remove oil or contamination so they will make good contact. be careful not to leave residue/ fuzz etc.to prevent good contact.
I have found bugs that love to buld a nest in points, carb vent holes,
gas tank fill vent cap holes. just most anything that they can plug up.
it seem at times it is their destiny to make mans life hectic!!
ol'Geo.

I AM AN IDIOT!!! Please don't kick me off the forum. I should not own tools let alone Cubs or anything gas powered. To start my tractor I have to jump from the battery across to the starter generator. Well you still need the key in the run position to get spark, so when the key is sitting on the tunnel, there ain't no spark.:bash2: I learned alot from the experience though. I learned that putting the points cover back on a narrow frame is a pain in the butt. Now gas is pouring out of my carb, so I guess it is time to jump into carb removal/cleaning/rebuilding. Cross your fingers. But once that is done, she should fire right up.

Nothing of the sort!!
One thing you are, thats honest!!
We all make little goofs some times.
The person who does nothing, makes no goofs.
You are learning like all of us. no matter the age, when a person is all finished learning he is passed on to another world.
ok, so does it try to run, with the key on???? and are you getting spark?
If so and you are pis- er leaking gas out the carb, lets try something simple.
turn off the gas and try to run it on what is in the fuel bowel. that is if it will now run???
I say this because sometimes a person is lucky and they have just a simple piece of dirt in the needle/seat keeping it from closing.
now report back to us so we can help.
This is fun,
I do admit i did laughed at the mistake, not at you, but at thinking about some of my mistakes in the past, I wished they were all that simple.
Geo.

Mike,
That's pretty darn funny!!! I've done some goofy things over the years myself. Hopefully you get that tractor up and running soon!
Jason

MrChic-

I haven't been fooled by the ignition key in a long time but I'm glad to know I'm not alone. Lately I've been fooled by the foot pedal safety switch on my 1250 and the pto lever being forward (engaged) on another. It's easy to do when the tractor will start without your being on it. When my mind's on the problem sometimes I'll overlook the obvious.

I'm sure you'll have it purring like a tiger soon. Wayne

Hey guys, thanks for the support. It is just so frustrating because I wanted to be doing maintenance like an oil and hydraulic fluid change and not spend the weekend chasing a non existent problem. Oh well you live and you learn.

Bill, how many times can use that big gallon of carb cleaner before it is all contaminated?

George, it fired right up after I walked away for a little break and went back. The leaking carb may have been starting fluid that I sprayed in there in my ill attempts to get running with out the key in. After I ran it out with the fuel off and opened the petcock again it didn't leak and started right up again. I still want to do the carb though just because I need to learn and the tractor will run better I am sure.

I learned a lot from the exercise in futility so that is the positive, oh yeah and she RUNS!!! That kohler shakes so bad I thought it would shake right off the jack stands.

I really appreciate the help. I am now going to focus on my front wheel issue so I can get her moving again.

If I got kicked off the forum every time I did something stupid, I would spend all my time trying to get back on and never would get any work done!!!

As someone already said but I believe it is worth repaeting, The guy who never does anything wrong probably isn't doing very much.

Glad to hear that it ran for you!

If you take the plug and stick your tongue on it, when you turn over the engine it should taste like lemons. Oh wait...I think that's for 9-volt batteries!:beer2:

I thought it was tongue on-the-flagpole on a freezing day to see if the lake was solid enough to Ice skate :bigeyes:

Some mention has been made of PB's "Tuneup-in-a-can". I will add my testimonial to the rest that the stuff works. A short blast in the carb while it's running and things just seem to get better. Follow the instructions on the can.

Tongue on the flagpole. Sheesh! Who would do something like that? (tongue firmly in cheek):biggrin2.gif: