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Hi, I'm new to the forum here and hoping to get some tips on a problem I'm having trouble figuring out. I have an old Snapper with an 8hp Briggs model 190702-2130-01 engine. This engine has been running very reliably for nearly 40 years and still runs very smooth except for a stalling issue that just started this year. What happens is that I can start the mower, it runs for about 5 minutes and stalls abruptly. I can wait a minute and it cranks back up, runs 1-2 minutes and stalls again. It does this consistently. It doesn't run rough or smoke or anything else, just abruptly stalls.

My first thought was that the float is sticking so I took the carb off and thoroughly cleaned it out and reassembled it. I also put a new air filter on it because it was time for one. This didn't help. I then bought a needle valve kit and replaced the needle valve and seal in the float bowl and that didn't help either. I verified I have a good spark, I continue to have a spark as it stalls so it's definitely a fuel issue. I've also replaced the fuel line and fuel filter so no issues with supply into the carb.

What else could be causing it to stall out regularly like this and then start back up fine after a minute or two?

Thanks,
Brian

Flush fuel tank. Install new fuel line from tank to carb. Clean it again. Blow out with compressed air and SAFETY GLASSES.

Yep, I did all that already. I also did pull the engine cover and cleaned out all the fins, just to be sure it wasn't overheating but I don't think it is. I changed the oil at the beginning of the season and verified it still has the right amount of oil and the oil looks good as well.

2 things to consider.
1. Your engine may have points/condensor, which can cause screwy symptoms. If you need to repair that, just snip the wire going to the points, and install the electronic coil. No need to pull the muffler.

2. Take off the valve cover and check the valve clearances with the engine cold. That may be your trouble.

I know I'm a newbie here but I tried to do all the basic stuff before posting here, was looking for some new ideas. It isn't the ignition, it isn't the valve clearances, the engine runs perfectly smooth and then stalls. Let it sit a minute and it cranks up fine. I cleaned out the fuel tank, replaced fuel lines and filter already, replaced float needle valve and seat. I appreciate any other tips that might be causing this.

Tried all of the stuff? What are the valve clearances then?

Just because you see a spark is meaningless.

You need to listen to folks that have worked on this equipment for a living.

Why would I wish you to check your valve clearances?

Why would I ask you about the ignition?

If the first 2 digits of the third set of numbers are 84 or less, then the engine had points at one time.

But I am leaning toward the valve clearances, as that also happens a lot.

When overheated, the block warps slightly, and the valve area will drift slightly toward the tappets, making the clearances too small, and the engine will start and run fine, but as the valve gets hot, it will expand, and the valve will no longer seal, as the tappet is preventing it from closing.
The engine stops, and cools down a bit, and the valve contracts from cooling, letting you start the engine again, etc.
Which is why you need to check your clearances when the engine is cold.

gpburdell said:

I know I'm a newbie here but I tried to do all the basic stuff before posting here, was looking for some new ideas. It isn't the ignition, it isn't the valve clearances, the engine runs perfectly smooth and then stalls. Let it sit a minute and it cranks up fine. I cleaned out the fuel tank, replaced fuel lines and filter already, replaced float needle valve and seat. I appreciate any other tips that might be causing this.

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When does it die? After you run it for 10 min? What sound does it make? does it sound bogged down or sound the same as if u killed the engine grounding the ignition.

If it stops going put, put, put and comes to a stop, get an ignition test light and run with it on your engine. When it stops\sputters, look to see if there is still spark. Maybe your ignition is starting to go bad...
Try running it and when it stalls, spray some starter fluid into the intake. If it responds, look into your carb.
Whatever. Get down an dirty to find your problem.

Step back and think what it is doing, sounds can point you to which part is not working - air+fuel+compression+ignition= running engine. That's what I do.

When the block warps, the valve seat also cocks a bit, so it has a poorer and poorer seal, and creates even more heat, making things worse.
So a proper valve job would be in order, cutting the seats and valves, not just lapping.
But this is all just speculation, which is why we do simple tests and measurements, so we don't waste time/money.

Here is a picture of my engine, it is a basic old 8HP pull start engine. I don't think it has a valve cover to take off and measure, I think I'd have to take the head off to get to the valves. There don't appear to be any points, just a coil next to the flywheel that has two wires, one is the spark plug wire, one is the wire you ground to kill the engine.

Fish, I don't mind checking the valve clearances, is there a way to do that on this type of engine without pulling the head off? It doesn't seem to be a gradual problem as it's heating up, it funs fine and then all of a sudden dies.

Upupandaway, it dies after 5-10 minutes and then dies every 1-2 minutes after that when you re-start it. It runs completely smooth until it dies and when it dies it mostly sounds like you turned the key off. Every now and then it will start to die and then recover and run a couple more minutes before dying. I have put an ignition light on it and watched it when it dies and the light shows good ignition as it's stalling.

I'll get some starter fluid and try spraying that in when it stalls and see if it fires.

gpburdell said:

it is a basic old 8HP pull start engine. I don't think it has a valve cover to take off and measure, I think I'd have to take the head off to get to the valves. There don't appear to be any points, just a coil next to the flywheel that has two wires, one is the spark plug wire, one is the wire you ground to kill the engine.

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Basic Briggs magneto sounds like. Pull the small kill wire. Should drain the tank dry if it's good. That coil needs to be LOAD TESTED to rule it out. As in a PET-4000. Look it up on youtube. Not some Christmas light inline waste of time ignition wire checker. All electrical circuits require load testing. As in full amp draw for that circuit.

gpburdell said:

checking the valve clearances, is there a way to do that on this type of engine without pulling the head off?

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Yes, there is a breather cover with two screws vertically that hold it on. Under that are your valve springs and keepers. That is where you check the gap. Use a new gasket when done and DON'T OVER TORQUE the screws when you reinstall the breather. Gentle snug is all you need.

You've missed something. Easy as that.

You claim to have checked everything and still doesn't run. Most likely a fuel issue. Again, that fuel tank has to be SPOTLESS inside. Carb as well.

Make a video and post it on youtube. Show us what you are working with.

Looks to me like that engine will have a points and condenser ignition system. Go, where does the second wire go, under the flywheel or to a ground connection? Either way I’m thinking you may have a coil with either a hot open or hot short, which causes lose of spark when the coil gets hot.
Slomo, why do you keep recommending that a DIY guy spend $40.00 on a spark tester that they will use once maybe twice. I’ve been at this for a lot of years and have yet to see where that tool has a location in my tool box. Inline tester is much cheaper and easier to understand for the average guy.

And to get to the valve chest you need to remove the carburettor because it is right behind it

Sorry if I misspoke, didn't mean to imply I'd checked everything or it would be fixed, lol. I've only checked the basic things that I knew to do and am trying to figure out what else to check. I've flushed and cleaned out the fuel tank again. Thank you for the tip on the valves, I'll take that cover off and see what the valves look like. I'll work on it this weekend and report back what I find.

gpburdell said:

Sorry if I misspoke, didn't mean to imply I'd checked everything or it would be fixed, lol. I've only checked the basic things that I knew to do and am trying to figure out what else to check. I've flushed and cleaned out the fuel tank again. Thank you for the tip on the valves, I'll take that cover off and see what the valves look like. I'll work on it this weekend and report back what I find.

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If you have the top off, snap a pic of the flywheel/coil area. The last set of numbers on the stamped model numbers is the date code. If it starts with the numbers 83/84 or less, then it has points, as that looks like the original coil. You may still get a flash on your ignition tester, as you would on a spark plug.

Checking the valve lash on these is more involved than with an OHV model, you might watch a youtube video of it or 2. I may do a video of it someday, as most of the youtubers don't do a good valve service, but it will give you a general idea.

From the looks of the air filter, it is an older engine with points, so I would look there first. The points are under the flywheel, so generally it is much easier to just snip the wire to the points, and bolt on a new electronic coil, so no need to pull the flywheel.
On a Snapper, getting to the valve cover is not the easiest thing either. But a check of the clearances is definitely a good diagnostic step.
I stress doing testing before just buying parts, as I hate wasting money.

So take a pic of the top of the engine with the starter off, so we know for sure if you have points, as it may have had the electronic kit installed on the old coil.

I forgot to include that last code. This engine is a model 190702, type 2130-01, code 85010810. The date code is 85 so sounds like it isn't points. The owner manual that came with the engine shows both a foam filter and cartridge so this must be right about the time they changed over. The valve clearance is 0.004 intake and 0.008 exhaust. The spec says it should be 5-7 on intake 9-11 on exhaust so it's just a tiny bit out of spec. I did not remove the head to get the piston in exactly the right position so possible I'm off a bit.

I cleaned the gas tank out again and I also discovered you can buy a whole carburetor for $26 so decided to try that since it wasn't expensive. That did not completely fix the issue but did change the behavior. It now tries to stall every couple of minutes but catches itself and recovers. I'm going to re-examine the fuel supply. I've also never taken the head off the mower, should I go ahead and do that and clean all the carbon out? I can tell from cleaning the spark plug there is definitely some build up in there.

85 will be points
Atom patiented the Hall Effect Trigger in 1966 ( from memory )
Although B & S could have installed them for a 50¢ royalty per unit they decided to wait till the patient expired which would have been 1996 if I got the 66 patent date correct .

Rivets said:

Slomo, why do you keep recommending that a DIY guy spend $40.00 on a spark tester that they will use once maybe twice. I’ve been at this for a lot of years and have yet to see where that tool has a location in my tool box. Inline tester is much cheaper and easier to understand for the average guy.

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Right tool for the job. They are $70.00 now. Better to see the full capabillity of the coil compared to a light which doesn't show the condition of the coil. Brown spark or nice blue purple spark. You can't tell much using the Christmas lights you guys use. Most people are fooled when the dome light works but the car won't start. Average guy doesn't need to be working on a lawn mower. Usually create more problems for themself.

Those (Christmas Tree Lights) have worked fine for me for the last 40 years and only. $12.00. Todays coils are not like those used will point/condenser ignition systems. If you are doing this as a business, then “maybe” you can justify purchasing an expensive tester, but for the DIY guy really doesn’t pay. Truthfully I can’t remember the last time I ran into a coil which was producing a “weak“ spark. If you really think you have a weak spark run this test. Gap a new, good plug to .150” and install in the cylinder. Install an inline tester and check for spark. Spark at .030” and no spark at .150” means weak coil. Cost to you, less than $15.00. I’d rather purchase a light bulb fluid tester or wire stretcher.

After reading the last posts, I am leaning toward valve lash. With that engine on that model, it is even more complicated. Removing and installing those valves can be tricky without the right tools. But I would take a peek under the head gasket, your engine could be badly worn, and a proper valve job would make it smoke like a freight train.
Take off the head, and take some pics.

Thanks, I'm going to get a head gasket and then I'll take it off and take some pictures

gpburdell said:

Thanks, I'm going to get a head gasket and then I'll take it off and take some pictures

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I would wait until after pulling the head, before ordering parts.

Rivets said:

Those (Christmas Tree Lights) have worked fine for me for the last 40 years and only. $12.00. Todays coils are not like those used will point/condenser ignition systems. If you are doing this as a business, then “maybe” you can justify purchasing an expensive tester, but for the DIY guy really doesn’t pay. Truthfully I can’t remember the last time I ran into a coil which was producing a “weak“ spark. If you really think you have a weak spark run this test. Gap a new, good plug to .150” and install in the cylinder. Install an inline tester and check for spark. Spark at .030” and no spark at .150” means weak coil. Cost to you, less than $15.00. I’d rather purchase a light bulb fluid tester or wire stretcher.

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Snap On or Harbor Freight take your pick. I like to see what the coil can and can't do.

And my cheaper method will do exactly what you want it to do.

Oh, I just figured it was a given if I take the head off I need to replace the gasket

gpburdell said:

Oh, I just figured it was a given if I take the head off I need to replace the gasket

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The older engines had a metal/asbestos clad gasket, which I have been know to reuse. I would wait until you know the condition of your engine before buying anything.

Have you replaced the spark plug?

Also you need to blow back through the fuel hose with the gas cap off.
Some of them old Briggs had a very fine screen inside the gas tank.
Some came out with the petcock and some did not. They will run for little while and shut down. (and re-start almost immediately, but the engine will usually not just quit fast it will hunt and surge first.
Also try running the engine with the kill wire off. Disconnected at the Magneto.


I suspect you are wasting time removing the head. Carbon buildup would not cause your DESCRIBED issue unless a piece got hung in the spark plug gap and that is not likely to be an intermittent thing as you describe.
Loose carbon would go out the exhaust port.

You really need to be careful with the TWO HEAD bolts that are by the exhaust port. They can twist off easily if you do not know how to pre-loosen them easily by doing the gentle rap shock to their head. The exhaust gets them hot and galls/seizes the threads in place.

Thanks, I'll try blowing back through the gas tank. My mower is an old Snapper riding mower that has a black plastic gas tank where I can't see the inside the tank because of how it's curved. It could have a screen in it, I'll see if I can find a borescope to peer inside with. Thanks for the tip on the exhaust bolts. I agree that is unlikely the problem but thought it might be a good idea to clean it out. I noticed in the manual it even says to remove the head periodically and clean it out, though I've never done it before. I'll also see if I can disconnect the kill wire right at the magneto.

Install a correctly gapped NEW spark plug. (and do not feel bad if it runs ok afterwards)

Yes leave the heads bolts alone for now they have been at rest since 1985 and good chance one or more will twist off. Your description does not warrant taking the head pull chance yet. NO NEED IN CLEANING ON A DEAD HORSE. You need to do some good through basic testing first.

I've got one of them old snappers with the 8-12 hp Briggs. One is manual start only and one is elec and manual.
Is yours both manual and electric crank? (or manual only??????????)
Does yours have the engine kill on the throttle lever?????????????or on a key switch?????????

In that 2 or so minutes that the engine won't restart, have you checked for spark in that time period?

The gas tank cap vent may be plugged on a engine that old .

Fish said:

Just because you see a spark is meaningless.

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THIS is why I prefer the PET-4000.

Forest#2 said:

Loose carbon would go out the exhaust port.

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It will also flake off and get between the piston and bore.

This is why all engine manufacturers say to pull the head and de-carbon the cylinder/s every say 5 years or example. Check YOUR engine manual for proper info.

Forest#2 said:

Have you replaced the spark plug?

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Very wise very wise.