# H60 Tecumseh runs very poorly



## bwright1818 (Dec 2, 2014)

I have an old Ariens, probably late 60s or early 70s. It has a well worn H60 Tecumseh. It fires right off but runs poorly, firing very intermitantly and finally stops. It restarts right off and does the same thing.

First, let me say that I am a boat mechanic with 40 years in the business; and I have some fairly extensive personal experience with small four stroke power equipment. This one has me temporarily stumped, though!! What I CAN say:

Fuel system: Tank is clean, filter is clean, good flow available to carb. Carb has been cleaned and preset adjustments to 1 1/2 open. From there, I have messed with them either way, to no avail. Sitting at rest, not running, there is no overflow. Pulling float bowl off and operating float by hand, gas flows and stops as it should. Float level is parallel to housing. No fuel trapped in float. New mounting gaskets were installed and they are oriented correctly.

Ignition system: Tried three different plugs, including one brand new one. Condenser leak tests excellent on a magneto analyzer. Points have been cleaned like new and adjusted to .020". When engine runs, an inline neon spark checker never falters, even when engine is clearly not firing.

Fuel: No water in gas that is visable. It IS ethanol fuel but it's only a few weeks old.

Power head: 120 psi compression. Valve clearance about .008 on both valves.

Spark plug condition: Engine will run correctly for about 10 seconds on a clean plug; then it starts its bad stuff. Pull the plug and it is pretty black, right away.

I have an H80 of the same vintage that will do the same thing, but it takes half a driveway of blowing, before it happens. Any ideas how to trouble shoot this any further? I was thinking a leak down test, which I do have tool to do it with....Also, I will probably take the carb off again and check it over again; however, I am confident it's clean. So I would be looking for some other exotic problem, which some of you guys may have seen?


----------



## SteelyTim (Nov 14, 2014)

First thing I do in this situation is grab a spray bottle of gas, shoot it a couple times into the carb, and then see if I can get it to run decently well while slowly spraying gas into the carb with a very light spray on the trigger. If it'll run that way, you'll know it's something with the carb.

If it's got a primer bulb, shoot carb cleaner into the primer hole (remove the primer hose and spray in there) to see if you can get gas coming out of the topside of the carb through the primer hole in the carb throat.

If you've got the time and are sick of screwing with the carb, pick up a carb for around $30 or so on ebay, slap it on and be done with it.

To me, H60s are a lot easier to get running than H80s when they have fuel issues. Let us know what you find.


----------



## greatwhitebuffalo (Feb 11, 2014)

bwright1818 said:


> I have an old Ariens, probably late 60s or early 70s. It has a well worn H60 Tecumseh. It fires right off but runs poorly, firing very intermitantly and finally stops. It restarts right off and does the same thing.
> 
> First, let me say that I am a boat mechanic with 40 years in the business; and I have some fairly extensive personal experience with small four stroke power equipment. This one has me temporarily stumped, though!! What I CAN say:
> 
> ...


see this thread

http://www.snowblowerforum.com/foru...ere-tecumseh-carb-problem-mystery-solved.html

there is a hidden passage in the Tecumseh carburetors that is very difficult to clean, see this thread. also there is a very tiny small passage in the main jet that feeds the idle circuit, it takes a .020" pin to clean it, a sewing pin. until you get all those passages cleaned out the carb many act up. there are 3 tiny idle/off idle discharge holes under the side welch plug, make sure they are clear- and there is 3 air bleeds in the entrance of the carb on choke side, make sure they are clear. best thing to do it soak the carb in a mixture of gasoline and mineral spirits for about a day or 2, then blow all those passages out with compressed air. you many have to drill the carb plug to get at the hidden idle jet passage and poke it out, then reseal it somehow.

or, just get a complete new or good carb somewhere.

it may also have intermittent spark problems i.e. points/condenser

on the Tec. engines, there is a filter screen in the bottom of the gas tank on the petcock, remove the entire petcock assembly and clean the screen- or remove the screen entirely and put an inline filter in.

on many of them the petcock itself is blocked with gunk and dirt. 

old fuel lines on these machines disintegrate and the rubber pieces come through the line and clog up the carb. 

you did put a needle/seat in, and check the float to make sure it's not filling up with gas inside ?

a quick carb rebuild/kit and quick cleaning usually gets these going, but if problems persist, EVERY PASSAGE MUST BE CLEANED- there's no way around it


----------



## motorhead64 (Dec 15, 2013)

BrigTrht1818
Don't overlook the cap vent on the tank, particularly if it is the older steel tank cap. The vent hole in that type cap gasket is a pinhole in cardboard. Try running with the cap off to see if you are getting a vacuum lock. It definitely sounds like a fuel supply problem. MH


----------



## bwright1818 (Dec 2, 2014)

motorhead64 said:


> BrigTrht1818
> Don't overlook the cap vent on the tank, particularly if it is the older steel tank cap. The vent hole in that type cap gasket is a pinhole in cardboard. Try running with the cap off to see if you are getting a vacuum lock. It definitely sounds like a fuel supply problem. MH


Thanks to all! The gas cap was a great idea....but, coincidentally, I had just put a new one on during all this, because a critter had chewed on it. At any rate, I can pull the new fuel line off the carb, hold it over a container, open the fuel valve and gas flows enough to run a small car engine.

I do know about the tiny passage in the main jet, as well as I am aware of the by pass holes under the welch plug. I rechecked the tiny jet in the main jet last night, with a bristle of a wire brush. It was okay. I have to admit that also last night, I reset the high speed jet to 1 1/2 again, just as a check. However, it didn't feel real difinitive when it bottomed out. Maybe something's going on there....something split and cracked, maybe. Although I can make it go too lean or too rich by messing with that needle, there does still seem to be some sort of fuel deal going on. If it were sucking oil around a loose valve stem, I don't THINK it would be fouling a clean plug within the seconds that it does, right?

I bet, in my life time, I have cleaned about 500 carbs. Seriously. But I know I still may have missed something. The older you get, the more you realize how dumb you really are...at least, I do.

I hope to mess with it again, this weekend. Thanks again! Keep those ideas coming!


----------



## scrappy (Dec 7, 2014)

My 2cents is weak spark. I never trust the neon type. Have had this adjustable gap Thexton for 20 plus years. My dads 1967/8 Tec will show 20kv with hand pulled and spark plug removed. 

This little tool has worked on cars trucks quads old harleys and it always shows the true spark. always a blue color spark, if yellow it's weak.

Also with points, I have found the points have to be free of oil & grease..

Amazon.com: Thexton THE404 Spark Tester: Automotive


----------



## bwright1818 (Dec 2, 2014)

I didn't mention that I also have an open gap checker...one that looks like a spark plug with the ground electrode removed and an alligator clip, to hook it to ground. On that test, the spark is reliable and blue. I actually took the points right out and carefully refaced them. I do this all the time on my own stuff and have great success with it. I then reinstalled them and reset them. This caused zero change in behavior of the engine. I admit that it SOUNDS as if the ignition is clearly dropping out sometimes. But again, the neon remains steady AND BRIGHT. The funny thing about single cylinder engines is that it's all or nothing. There is no comparing compression readings or doing a balance test! They can be tougher than muliti-cylinder engines because no matter what the problem is, it's either firing or not! That's one reason I will sometimes resort to the neon checkers; but I agree, that is only after an open gap test.

The funny thing with this neon test is that, usually, if the plug is fouling, the KV will go down and you can kind of see and interpret that, in the intensity of the flash. THIS flash remains bright, whether, skipping or not. Normally, that would mean lean misfire...but the plug comes out black and sometimes quite wet. I do have a squirt can with gas in it. I guess I should try that, even though I was _thinking_ too rich.

This old blower is probably not worth the powder to blow it to ****....but now I HAVE to know the answer!


----------



## classiccat (Mar 1, 2014)

I recently had similar problems with my HM80; started-off strong at 1 1/2 turns-out and started running like butt when warm...Plugs foulin and all of that mess. Once I leaned-out the main mixture valve (_bowl_) 1/2 turn (_from 1 1/2 to 1 turn out_), it ran strong. ...that was before I ripped the head-off 

You sound like you know this but just in case...make adjustments on a warm engine & do 1/8 turn at a time and wait for the engine to respond.


----------



## motorhead64 (Dec 15, 2013)

bwright1818
I would have to know, too. I would pull the head and eyeball the state of the combustion chamber. It may be in severe need of decarbonizing. If your plug is fouling in such a short run, everything is black in there. I would also adjust your float to a slightly lower setting...it should be a little lower than level to insure it is not flooding the cylinder. While the head is off, see if you have excessive wear on the valve guides which is not uncommon on older H60 engines. MH


----------



## scrappy (Dec 7, 2014)

bwright1818 said:


> I didn't mention that I also have an open gap checker...one that looks like a spark plug with the ground electrode removed and an alligator clip, to hook it to ground. On that test, the spark is reliable and blue. I actually took the points right out and carefully refaced them. I do this all the time on my own stuff and have great success with it. I then reinstalled them and reset them. This caused zero change in behavior of the engine. I admit that it SOUNDS as if the ignition is clearly dropping out sometimes. But again, the neon remains steady AND BRIGHT. The funny thing about single cylinder engines is that it's all or nothing. There is no comparing compression readings or doing a balance test! They can be tougher than muliti-cylinder engines because no matter what the problem is, it's either firing or not! That's one reason I will sometimes resort to the neon checkers; but I agree, that is only after an open gap test.
> 
> The funny thing with this neon test is that, usually, if the plug is fouling, the KV will go down and you can kind of see and interpret that, in the intensity of the flash. THIS flash remains bright, whether, skipping or not. Normally, that would mean lean misfire...but the plug comes out black and sometimes quite wet. I do have a squirt can with gas in it. I guess I should try that, even though I was _thinking_ too rich.
> 
> This old blower is probably not worth the powder to blow it to ****....but now I HAVE to know the answer!


 OK We are on the same page. A dead mis-fire is a no start. LOL 
post up what you find.

~scrappy


----------



## scrappy (Dec 7, 2014)

motorhead64 said:


> bwright1818
> I would have to know, too. I would pull the head and eyeball the state of the combustion chamber. It may be in severe need of decarbonizing. If your plug is fouling in such a short run, everything is black in there. I would also adjust your float to a slightly lower setting...it should be a little lower than level to insure it is not flooding the cylinder. While the head is off, see if you have excessive wear on the valve guides which is not uncommon on older H60 engines. MH


Agree with removing the head for a look see.


----------



## bwright1818 (Dec 2, 2014)

Sorry if I was too wordy. I tend to be thorough, which, when describing stuff, means wordy....and stuff actually gets LOST in the translation! Yeah, it always can be started. It just runs bad and will sometimes quit.

I have five blowers and a generator, all with Tecumseh horizontal shaft engines. I do find that they can be persnikity about the carb adjustments; but usually, I can tweek them back into the groove without very much trouble. I also have one Briggs powered generator. Its adjustments seem more stable but doing a carb job is a lot harder. The Tecumsehs, I can usually drop the bowl, on my back, outside in a storm, if need be and have them up and running again in about ten minutes. But THIS H60 seems to have more exotic problems than usual. (Yes, I have had THIS carb off and on my bench and parts washer, to clean it.)

What I can see of the combustion chamber through the plug hole is pretty black but not super caked up. I have no doubt the valve guides are worn, though. I hope that's not the end problem. I was thinking that I could briefly take the side valve cover and breather off again and run it for a bit, with a new, clean spark plug. I was thinking that, that way, if it were drawing oil in around the stem, it might be less inclined to, with the cover off and wide open to the clean air.....you know, just as a minute or so test. If it ran okay that way, it might show the stem was the problem? Stupid idea?

At any rate, I will take the carb off again, this weekend, regardless.


----------



## suspicionofignorance2 (Jan 26, 2014)

I'm wondering if you have an old coil starting to fail...engine warms up, coil internal wiring either shorts or opens...reducing or eliminating the HV...You may have to quickly check for healthy spark when engine dies,,,Is it ?


----------



## Grunt (Nov 11, 2013)

Hello and welcome to the forum bwright1818. With your experience in small engines, this must be a real head scratcher. Do you ever have a problem with the recoil pulling back when you start it? Although very rare on snow blower engines and next to impossible on marine engines, I wonder if the flywheel key is sheared and the engine is slightly out of time? The soot on the spark plug tells me it is running to rich, almost like the choke is still closed. Are you testing the engine with the heater box on or off? Unless you are getting some oil smoke from the muffler,I personally don't think a valve guide would cause this problem. Since you have a leak down tester, I would give it a try, nothing to loose, and a guarantee that a valve is not hanging up. The more questions you and we ask, the closer we get to the fix.


----------



## bwright1818 (Dec 2, 2014)

That's great! Thanks! I'm 99.99999% sure the flywheel key is okay; although yes, it does kick back when pulled over, sometimes. The engine had this problem, so I went in and checked over stuff in the magneto. The key was fine then; and when I installed the flywheel, I actually used a torque wrench. (I have the Tecumseh mechanic's handbook, which is a great book. TONS of info.) Anyway, after the mag service, the engine still ran the same way. It's interesting that you brink up the kick-back, though. At least once, as it was chugging and puffing, it back-fired and RAN BACKWARDS for maybe four revolutions. While I guess I am kind of used to that, from two-stroke stuff, I thought, "How can a four-stroke do that??" I just figured that, although it's a four stroke, the magneto fires every single revolution; so as long as there is fuel in the cylinder, anything could happen..........Hmmmm, burnable fuel in the cylinder, when there shouldn't be......That might be a significant clue....

As for the leak down, I have a 10/32 that runs perfect. I should do a leak down on that, first, to establish some kind of base expectation for the H60.......I have never done one on power equipment, before. Only outboard motors and stern drive engines.


----------



## Grunt (Nov 11, 2013)

I don't have an ACTUAL leak down tester. I made one from the metal shell of a spark plug and welded a female air hose fitting to it. I apply 15-20 psi of air with the piston at top dead center of the compression stroke and listen for where the air comes out. I have found many leaky exhaust valves on flat head engines this way. Your compression readings and valve clearance being good has me stumped also. 

Tecumseh made an off-set dial indicator for checking the timing on their flat heads which is still available but expensive for the limited use it will get. Most people pull the head and use a digital caliper to measure the piston top to cylinder top spec and adjust the timing according to the points ignition section in the manual. I have never done it, but I have read where people adjust the point gap narrower to achieve the correct timing. Going from the spec of .020 to maybe .017??

Another thought (uh ohh) is your oil level good and has no gasoline smell? If your carb has been dumping fuel into the cylinder, you may now have an over filled gas contaminated sump?


----------



## bwright1818 (Dec 2, 2014)

Well, a minor update....I couldn't leak down test the 10/32....It has a compression release built onto the cam!! Duh!! I have seen that thing, too; so I should have known!


----------



## Grunt (Nov 11, 2013)

Try moving the piston down a little off the compression stroke and try again. On power stroke, both valves should be closed. The compression release works just before TDC.


----------



## suspicionofignorance2 (Jan 26, 2014)

I'm confused...I didn't think a vintage 6hp had a compression release mechanism..? More so, with a 120 psi reading 
on compression test..
If it were mine, I'd be focusing on that coil...and checking health of the spark when it fails...as I mentioned earlier...


----------



## scrappy (Dec 7, 2014)

With the open gap spark tester, set at 'SE' or about 5KV you can clip it to the spark plug, connect the plug wire to the tester end and run it under load. If you have a nice blue spark when it dies.. not an ignition problem.


----------



## bwright1818 (Dec 2, 2014)

scrappy said:


> With the open gap spark tester, set at 'SE' or about 5KV you can clip it to the spark plug, connect the plug wire to the tester end and run it under load. If you have a nice blue spark when it dies.. not an ignition problem.


I don't have an open air gap tester that can be set to a KV number but I do have one that could be put in line and run. About what distance apart would you think that the 5 KV would end up being?


----------



## scrappy (Dec 7, 2014)

bwright1818 said:


> I don't have an open air gap tester that can be set to a KV number but I do have one that could be put in line and run. About what distance apart would you think that the 5 KV would end up being?


 about 1/8 of an inch


----------



## bwright1818 (Dec 2, 2014)

Okay, so today, I went out and flogged the H60, some more. You guys that were leaning towards spark seem to be right and I was wrong!

Before I did anything, I tried some new gas, just to be sure...no dice.

Then, after you guys mentioning an inline, RUNNING, open-gap tester, which I didn't have with me today, I decided to try something.....I opened the plug gap way up...probably .050" or so. It wouldn't even start. Then I closed the gap up to maybe .010 or less. It started and ran much better than it had, but not great. Encouraged, I scrounged the basement and found a used coil, went back out and put it on. I also installed a new plug wire and boot, while I was at it. It runs pretty well, now! Thanks to everyone! I learned something from this: Don't believe the neon testers!!! Funny, I used to have good luck with them; but they failed me this time!! I am going to get one of those open gap ones, for SURE!! It would have saved me a lot of aggravation!!

Now the next problem...Once it was running well enough to idle down some, I heard a mild grinding noise. Seems like the flywheel or rotating blower intake screen, rubbing on the blower housing. Then I saw the output end of the crank floating around a bit. Uh oh....So, while it was running, I held the crank up with a screw driver. This dropped the front part of the crank and the noise went away. MAN, is this thing worn out! Anyway, I found another block cover on eBay, so that's coming. Hopefully it will be better than mine!! I also bet the crank float problem might be causing what I had left of a little misfire, due to point float? Maybe that's part of the reason she was kicking back on start up, too...???

Anyway, thanks very much for ALL the input and ideas, everyone! You all helped me to rethink this whole thing, and it worked! (I am also glad it wasn't the carb! I would have been a bit MORE embarrassed than I already am!!

Bill


----------



## scrappy (Dec 7, 2014)

My Thexton gap tester solves another mystery.


----------



## Shryp (Jan 1, 2011)

Could be the old coil was a looser fit from the floating. Maybe it just needed regapped.


----------



## suspicionofignorance2 (Jan 26, 2014)

Good job...Coil troubles can be confusing..The ebay block piece should fix it right up...You say its a "worn" eng...But remember ---you got 120psi compression on it..I'd be very happy with that..


----------



## GustoGuy (Nov 19, 2012)

Good to hear you got it running well. I hope it continues to run well for you from now on.


----------



## RoyP (Oct 16, 2014)

bwright1818 said:


> I have an old Ariens, probably late 60s or early 70s. It has a well worn H60 Tecumseh. It fires right off but runs poorly, firing very intermitantly and finally stops. It restarts right off and does the same thing.
> 
> First, let me say that I am a boat mechanic with 40 years in the business; and I have some fairly extensive personal experience with small four stroke power equipment. This one has me temporarily stumped, though!! What I CAN say:
> 
> ...


Soak the carb in NAPA Carb cleaner, gallon pail. remove all the jets that you can.....soak for about 2 hours....rinse with water......blow dry every possible drop of water out of it. Blow air through every possible hole that you can see. Or......buy a new carb..


----------

