B&S 1980 5hp no spark

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  #1  
Old 03-21-09, 05:00 PM
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B&S 1980 5hp no spark

Model-150202
Type-0398-01
Code-80101307

New to this forum and small engine repair. This engine is on a front-tine Till-N-Plow implement. It hasn't been run in several years. Been kept covered in a loafing shed (3-sided shed out of rain). The plug is good. The plug wire is old but looks OK. I don't know how to test the coil and can't get the flywheel off. Any advice would be much appreciated. Thanks.
 
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  #2  
Old 03-21-09, 05:12 PM
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Why would you want to remove the flywheel ?

This engine has a electronic ignition module (coil) on it, Remove the small black kill switch wire from the coil then check for spark again.

If you still have no spark the coil has failed.

If you now have spark with the small kill wire disconnected trace this wire back to the kill switch. Check for any bare spots that may be touching a ground source. Also check the kill switch for shorts.


Good Luck
 
  #3  
Old 03-21-09, 05:48 PM
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Thanks for the reply 31YTech. I have read that some small engines have a condenser and points behind the flywheel. So I was going to check. Did I say I was new to small engine repair

The coil has 3 wires: a plug wire, a black wire going behind the flywheel, and a small ground wire. The black wire is not removable. This is a 29 yr old engine.

Is there a way I can ohm out the coil to test it?
 
  #4  
Old 03-21-09, 06:19 PM
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OK, Sorry....I had my head up my butt....

There is no ohms specs that I know of on the coil, Your problem most likely is the points and condenser. If you can't get the flywheel off you can purchase coil part # 397358 and convert to electronic ignition. Just cut the one small black wire as far up under the flywheel as you can and leave the points in place. The new coil will come with a new kill wire as well.

Sorry again for any confusion....

Good Luck
 
  #5  
Old 03-21-09, 07:16 PM
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If the coil is good you can convert to Magnetron without buying a new one. The kit is p/n 394970. Forget about pulling the flywheel and messing with the points.
 
  #6  
Old 03-21-09, 07:43 PM
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That's interesting Roy; exactly what is difference between a electronic ign coil and a magnetron? Thanks.
 
  #7  
Old 03-21-09, 07:47 PM
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There are no electronic components in the Magnetron kit, it is simply an impulse coil that clips on to the existing unit. You do need a soldering gun to properly install it.
 
  #8  
Old 03-21-09, 08:37 PM
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OK, I think I understand. Unfortunately I don't know if my existing coil is any good. I might have dirty points (mud dobbers), bad condenser, a short, or a bad coil. I guess my choices are to find out how to remove the flywheel, or go with the electronic ign coil recommended by 31. Thanks for the feedback.
 
  #9  
Old 03-21-09, 08:49 PM
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I suggest putting the electronic coil on it and be done with ignition problems for the rest of it's life. It doesn't give trouble like points do.
 
  #10  
Old 03-22-09, 04:52 AM
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I think that's a good idea cheese. Thanks to all who responded.
 
  #11  
Old 03-22-09, 08:25 AM
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Most of the time when a engine like this sits in storage the flywheel magnet rusts. Sand the magnets then loosen the 2 coil screws. Put a business card between the flywheel magnets and the coil (to gap) tighten the screws and see if you have spark. Troy
 
  #12  
Old 03-22-09, 12:08 PM
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Good advice Troy. What's that saying, 'all things being equal, the simplest solution is usually best.' I took emery cloth to every contact point (flywheel magnet, coil contact points (x4), and ground wire. I get some current now. I can't see a spark (might be too light during the day) but I can feel the current if I hold the end of the plug wire. How much current should be going through the wire? This is an old engine so no high voltage I suspect. I will need to clean out the fuel system before It will start even if adequate fire is present. Seems to have decent compression.
 
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Old 03-22-09, 11:20 PM
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It has high voltage...should be enough to make a nice spark. If not, the condenser is probably weak/leaking. I've never seen a rusty flywheel cause a problem in my 17 years of small engine repair...but a lot of people say sand it off, so who knows...
 
  #14  
Old 03-23-09, 05:14 AM
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Originally Posted by cheese View Post
I've never seen a rusty flywheel cause a problem in my 17 years of small engine repair...but a lot of people say sand it off, so who knows...

I read that yesterday, It's just a myth that everyone wants to follow. But in reality doesn't help a bit with producing stronger spark.....
 
  #15  
Old 03-23-09, 07:08 AM
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Y'all may be correct; maybe the emery cloth didn't do anything. When I first check for spark a couple of weeks ago, I was insulated from the wire and saw no spark. When I did it yesterday I was not insulated and felt some current. Maybe the current was there all along just not enough to jump the gap the first time I checked. Anyway, I'll just go ahead and replace the coil with the electronic version and be done with it as was suggested. That's a reasonable expense to get this implement up and running.
 
  #16  
Old 03-25-09, 04:50 AM
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Sorry if the sanding thing was bad advice, I guess I should quit doing small engine repair after 35 years.
 
  #17  
Old 03-25-09, 05:18 AM
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Still, the recommendation to knock some rust off is a good idea. It took me only a couple of minutes. In addition to the flywheel I also cleaned the coil mounting contacts and the coil wire. How many times has a bad ground caused hours of lost time trying to diagnose an intermittent problem. I really appreciate all advice I can getBeer 4U2
 
  #18  
Old 04-10-09, 12:17 PM
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Electronic coil

Excuse me for butting in. You say I just need to replace the old coil with the electronic coil? My mechanic says i have to get a different flywheel. Sounded kinda crazy to me. Thanks
 
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Old 04-10-09, 01:10 PM
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Electronic coil

Excuse me for butting in. You say I just need to replace the old coil with the electronic coil? My mechanic says i have to get a different flywheel. Sounded kinda crazy to me. Thanks
 
  #20  
Old 04-10-09, 01:12 PM
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Originally Posted by schmoedog View Post
Excuse me for butting in. You say I just need to replace the old coil with the electronic coil? My mechanic says i have to get a different flywheel. Sounded kinda crazy to me. Thanks
I visited a trusted small engine mechanic and he confirmed the advice I received here, that I could just replace the existing coil and leave the old points in place w/o removing the flywheel. I purchased the new coil, and a new fuel tank because mine had a lot of scale rust inside. As soon as I clean up some other priority projects I'll put the tank, carb (removed to clean), and new coil back on and report my results.
 
  #21  
Old 04-10-09, 07:36 PM
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Schmoedog, The conversion to electronic ignition does not require a new flywheel. They both use the exact same flywheel, even same part number. Sounds like your mechanic may be in the wrong line of work???
 
  #22  
Old 05-02-09, 02:10 PM
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OK guys, I reassembled everything. I have much more spark with the new coil Thanks for that advice! I also installed a new fuel tank and cleaned the carb. I filled the fuel tank and changed the oil.

That's where things stalled. I have not had any success in starting the engine. Like I said, plenty spark. I'm really clueless on how to diagnose fuel problems. I don't think I'm getting any fuel because the plug is dry as a bone after 10-15 pulls with the choke out. There is some compression; I can feel it with my finger but I have not put a compression gauge on it. I think I'm gonna need some more help

Oh, and I had the model number wrong in my first post; it's 130202 not 150202. Too much rust
 
  #23  
Old 05-02-09, 06:40 PM
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Getting a compression reading might be the next best step. Did you install a new gasket and diaphragm in the carb?
 
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Old 05-03-09, 07:47 AM
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Well Cheese, now I feel more than a little stoopid. I got this tiller from my father in-law who said it worked for him. So I broke one of the primary rules of working on an engine that won't start, I didn't do a compression check; at least not a real one And now when I put my gauge on it I get almost nothing. The needle jumps VERY briefly when I yank the rope, but doesn't stay up. So I checked the gauge on my lawnmower and it stays between 75 and 100. The gauge is good but the tiller motor evidently isn't.

Are there any tricks to doing a comp check on these small engines? I just screwed the gauge in and yanked the rope...several times. Nothing.

I'm afraid to think about what the problem might be
 
  #25  
Old 05-03-09, 01:37 PM
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Forgot to add that I replaced the gasket between the carb and fuel tank but not the one between the carb and the engine block. The latter gasket looked like it was making a good seal, the tank gasket was definitely not making a seal. And I replaced the diaphragm. Sorry for the oversight in my previous post.
 
  #26  
Old 05-03-09, 07:47 PM
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These engines are notorious for having stuck valves. I'd pop the head off and have a look. Chances are with some penetrating oil and gentle persuasion, the valve will come loose. I am sure this is the problem, since do you register the existence of "some" compression with the brief jump of the needle. That means the piston is moving.
 
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Old 05-03-09, 07:52 PM
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Oh yeah, the piston's moving. I can feel the suction with my finger on the plug hole and I can feel the exhaust. That's why I originally thought it was a solid engine.

I was thinking rings; totally forgot about a stuck valve. No experience with small engines. I'll yank the head and look. Thx.
 
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Old 05-09-09, 12:15 PM
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Finally made time to pull the head. The valves appear to be operating fine. The cylinder walls look good also. I don't see anything obviously wrong.

Reassembled and still no compression. Acts as though the timing is way off. Is that possible?
 

Last edited by Penthor-Mul; 05-09-09 at 02:54 PM.
  #29  
Old 05-09-09, 08:11 PM
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put about a teaspoon of motor oil in the cylinder thru the spark plug hole, this may help enough to get it to run, after all you said its been sitting for a while, a little lube wont hurt a thing, may have a stuck ring rust on a valve seat or valve face, any way it wont hurt to try
 
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Old 05-09-09, 10:03 PM
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With the piston moving and valves operating, you should have some compression even if the rings are stuck to the piston. I'd say you either have more compression than you think (maybe bad gauge?) or there is something you haven't seen. Do the valves turn when they are down?
 
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Old 05-10-09, 05:36 AM
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tracy, I tried the oil thing this morning with my coffee. I've done this on truck engines before to check for bad rings. Same results, no compression registered on the gauge, only a quick spike when I yank the rope. [I need to build an adapter so that I can turn the engine over with my drill motor with the flywheel off. That would be so much easier than remounting the rewind housing each time.]

cheese, I'm beginning to doubt my compression gauge even though it seems to work fine on my electric-start riding lawnmower. Maybe I just can't yank the rope fast enough The valves seem to operate fine and seat well (how can I tell if the valves are not seating well?). They do not turn when I rotate the flywheel, although I can rotate them by hand, and I applied some oil to their shafts when they are in the open position. There is always the possibility that I am not seeing something

If there is adequate compression that my gauge is not measuring, then the question is why am I not getting fuel. I guess I could have hooked up the linkage wrong, or maybe the fuel intake pipe is clogged (how can I clean it out), or maybe something else. I did install a new diaphragm and clean all the orifices that I could find. I guess I could soak the carb in some carb cleaner, although I think I cleaned it well.

I really appreciate everyone's patience. I'm learning, slowly
 
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Old 05-10-09, 06:16 AM
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thinking you may not be able to pull the rope fast enough to ge a good reading, would try a tea spoon of gas in the cylinder and see what happens, if it fires and trys to run, then you need to look at the fuel system, also the diaphram uses back pressure off of the crankcase to make it function, so it may be a bear to get started that first time, at least that may give you a ray of hope
 
  #33  
Old 05-11-09, 11:32 PM
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I was thinking the same thing... you might want to try a little gas in the spark plug hole to see if it will run.

When the valves are fully seated, can you turn them by hand? (just by pressing with your thumb and rotating your thumb)
 
  #34  
Old 05-12-09, 05:15 PM
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When I added 1ml gas to the cylinder I got about 4-6 combustion cycles. Seems to be running for a short time.

I can rotate the intake valve with my thumb on top during the intake stroke and compression stroke (up or down position), and not at any other time.

I can rotate the exhaust valve only when it is up during the exhaust stroke.

Carb problem?
 
  #35  
Old 05-12-09, 10:55 PM
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So when the valve is all the way down on the seat, you can still rotate it? It may be that the valve stem clearances are in need of adjusting. Before going that far...how well did the engine run when you added gas? Did it bust right off and fire up, or was it a labored barely-running type of thing? Can you feed a little gas by dribbling it into the carb while it is running to keep it running? (careful how you do this, use a small squirt bottle or something that won't catch fire if the engine pops back out the carb).
 
  #36  
Old 05-13-09, 06:01 PM
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Yes, I can still rotate the intake valve when it is all the way down between the compression stroke and the power stroke. After the power stroke, at the beginning of the exhaust stroke when the intake valve is still down, I cannot rotate it until it goes down for the next compression stroke.

The exhaust valve cannot be rotated when it is down or in the closed position.

Both valves seem to be seating well and are not noticeably loose.

I retested the firing by adding fuel to the cylinder again. It starts right up. I can get up to about 8-10 combustions on 1ml, but I cannot keep it running by adding fuel to the carb. I'm not really fast enough and since it tried to ignite the fuel in the carb I don't think I care to try that again

It really sounds like it will run if fuel can be sucked up from the tank. I'm beginning to think that the intake pipe which extends into the tank is clogged. The engine sat up for a few years and the gas went bad (that's putting it mildly). It may have 'gunked' up the intake screen or pipe. I cleaned it and blew it out with air but maybe I didn't get it clean. Can this intake pipes be replaced?
 
  #37  
Old 05-13-09, 11:36 PM
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Yes, the pipe can be replaced. I agree with your conclusion as well... It sounds like the engine is ok, but the carb is clogged still. These carbs can clean up so easily sometimes, or refuse to work ever no matter what you do .
 
  #38  
Old 05-14-09, 04:08 PM
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So I made an adapter for my drill motor to spin the shaft faster. It worked well and I actually got the motor started by choking it (and dern near twisted my hand off in the process). However I could not keep it going very long; maybe 30 seconds at a time. I fiddled with the linkage and the needle valve with little success. I have the needle valve backed out 1 full turn. I'm not sure if I have the throttle return spring and associated linkage hooked up right I think I may be down to a linkage/carb adjustment problem now.

I'm still unsure about the 2 intake pipes extending from the bottom of the carb. I guess one or both could still be clogged at least partially. And I may yet just replace them to be sure they are in good shape. Can someone tell me what the purpose of each pipe is?

Thx for the help guys, I'm almost thereBeer 4U2
 
  #39  
Old 05-14-09, 08:22 PM
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One pipe picks up fuel from the tank, going to the fuel pump, which dumps it into the cup in the tank under the carb (carb bowl). It fills the bowl and the excess runs out back into the tank. The shorter one picks up fuel from the bowl and suplies the main jet in the carb.

Your mixture screw should be set 1 1/2 to 2 full revolutions out from lightly seated.
 
  #40  
Old 06-20-09, 10:35 AM
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OK, back on the job here (been busy with the day job). Turns out that the fuel pick-up pipe was clogged and it wasn't delivering fuel to the little bowl. Probably from the gas turning into molasses after yrs of non-use. I could fill the bowl and it would run until it was empty. After solving that problem the engine seems to run OK. I also "wired" out the two orifices beneath the needle valve to be sure they were clear. I have not yet adjusted everything to working status though. When I started it there was a small fuel leak where the carb mounts on the tank, on the muffler side. With the muffler about 0.5" from the tank and leak I thought I would solve that problem before I burned down the garage

Is anyone else wondering why they mounted the tank so close to the muffler knowing that the muffler was gonna get so hot? That just doesn't seem to safe to me.

Anyway, I'm still concerned that I have not connected the throttle return spring correctly. I'll be able to tinker with it more after solving the fuel leak problem. I may be back with more questions then.

Thanks for all the help and patience so far. The advice has been spot on. Great forum

Penthor
 
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