I have a 16 hp Craftsman lawn tractor 917-255821 that has good spark, has fuel, has compression, has new battery, new spark plugs, has rebuilt carb, has new mag, but will only sputter when cranking but will not catch and run. It ran yesterday for a few minutes but will not restart.
Quick start will not start it. Any ideas... it does not make sense.

Your carb is here: BRIGGS&STRATTON | Model #402707 (0157-02 - 0157-02) | BRIGGS & STRATTON GAS ENGINE | AIR CLEANER AND CARBURETOR | SearsPartsDirect.com (http://www.searspartsdirect.com/partsdirect/getSubComp.pd?modelNumber=402707%20(0157-02%20-%200157-02)&productCategoryId=1503500&brandId=1245&modelName=BRIGGS-%26-STRATTON-GAS-ENGINE&diagramPageId=00002&componentDescription=AIR%20CLEANER%20AND%20CARBURE TOR&documentId=00014181&backToLink=Return%20to%20Sub%20Components%20list)

I think is see an idle screw #48 and a mixture screw #44. Am I correct?

There doesn't appear to be a low and high speed mixture screw, correct?

Did this mower ever backfire bad once. There is a possibility the timing change jumped a tooth and that would throw the valves off to run.
What was the mag set at?

The sputter could be the mag is set wrong or a fuel to air mixture setting in carb is off, that's if the fuel pump working and float is set right.

Is there NEW fuel in it. Not last years. When ever having problems on season start up always get New fuel. I have tanks topped but fuel was not high in octane. Use High test when working on a mower to get started.

I didn't see a fuel filter change here was there?

What I like to do to prove the engine itself is in good running condition, I use a spray bottle of fresh gas and spray directly in carb and if the mower runs and sounds good the its carb fuel that's bad in the link. The air fuel mixture just may be off and needs adjusted. At present it needs more fuel

Never use either starting fluid...

Your carb is here: BRIGGS&STRATTON | Model #402707 (0157-02 - 0157-02) | BRIGGS & STRATTON GAS ENGINE | AIR CLEANER AND CARBURETOR | SearsPartsDirect.com (http://www.searspartsdirect.com/partsdirect/getSubComp.pd?modelNumber=402707%20(0157-02%20-%200157-02)&productCategoryId=1503500&brandId=1245&modelName=BRIGGS-%26-STRATTON-GAS-ENGINE&diagramPageId=00002&componentDescription=AIR%20CLEANER%20AND%20CARBURE TOR&documentId=00014181&backToLink=Return%20to%20Sub%20Components%20list)

I think is see an idle screw #48 and a mixture screw #44. Am I correct?

There doesn't appear to be a low and high speed mixture screw, correct?

You are correct. I changed the mixture screw #44.

You are correct. I changed the mixture screw #44.

No there is no high and low speed screw.

OK. Try this:

Put it in whatever the start position is. Choke, fast.
Take the mix screw and turn it in all the way until it stops. Back out 1.5 turns.
Remove plug and Spray carb cleaner in the plug hole. Replace plug.
Try to start
If engine starts, play with mixture scrw until engne runs smooth.

OK. try this:

put it in whatever the start position is. Choke, fast.
Take the mix screw and turn it in all the way until it stops. Back out 1.5 turns.
Remove plug and Spray carb cleaner in the plug hole. replace plug.
Try to start
If engine starts, play with mixture scrw until engne runs smooth.

Well I tried all of this and it still did not work. This is driving me crazy because I have never not been able to get a mower fixed. Any other ideas would be appreciated.

Does #12, the choke, close and open correctly.

Is this choke opened by the engine intake of air?

Does #12, the choke, close and open correctly.

Is this choke opened by the engine intake of air?

It is a manual choke. It gets to the point where it sounds like it is running with the start going, but as soon as you let go of the key the motor stops too.

The will be combustion smoke coming out of the exhaust and everything.

I have noticed that the "drivers" side (left) spark plug is wet with gas and the right one is not, but hey both are sparking when I check.

but as soon as you let go of the key the motor stops too.
There may be a couple of problems here. The" key" letting go should not have this effect at all. Maybe you have a bad connection that's shutting of the engine ( kill on the coil ) I would check that out. So please be very detailed on the key thing. You may need a new ignition switch also. It can be hot wired too for testing the engine / gas plug problem/

There may be a couple of problems here. The" key" letting go should not have this effect at all. Maybe you have a bad connection thats shutting of the engine ( kill on the coil ) I would check that out. So please be very detailed on the key thing. You may need a new ignition switch also. It can be hot wired too for testing the engine / gas plug problem/

I got the mower running by accident. With the right side spark plug removed to check if it was sparking the motor kicked off and ran with the spark plug out of the cyclinger. HUH? That almost seems as if it is now timing related but the keyway is in a correct. How do I check this twin cylinder engine to see if the timing is correct. To talk apples and apples please referr to the driverside (on car) cylinder as the left as seen sitting on the mower. Thanks a lot everyone for your help.

Is there spark on the plug you pulled? If not the problem could either be a bad plug, plug wire, magneto or a bad diode. There is one diode for each cylinder on a twin cylinder

Is there spark on the plug you pulled? If not the problem could either be a bad plug, plug wire, magneto or a bad diode. There is one diode for each cylinder on a twin cylinder

The spark plug that was pulled and laying on the engine was in fact sparking good and the motor was running very smoothly which amazed me.

Before this gets internal lets see if the spark is "hot" strong enough. Take a good plug or the one that's there and cut the ground where it starts to bend over to center of plug.

Before testing pull other plug wire. Now put cut plug on a ground or mower lay it to see it and crank engine. If the spark doesn't make that gap then its back to magneto or a bad diode.

Plug wire on and lay plug on head

Did this mower ever backfire bad once. There is a possibility the timing change jumped a tooth and that would throw the valves off to run.
What was the mag set at?

The sputter could be the mag is set wrong or a fuel to air mixture setting in carb is off, thats if the fuel pump working and float is set right.

Is there NEW fuel in it. Not last years. When ever having problems on season start up always get New fuel. I have tanks topped but fuel was not high in octane. Use High test when working on a mower to get started.

I didn't see a fuel filter change here was there?

What I like to do to prove the engine itself is in good running condition, I use a spray bottle of fresh gas and spray directly in carb and if the mower runs and sounds good the its carb fuel thats bad in the link. The air fuel mixture just may be off and needs adjusted. At present it needs more fuel

Never use either starting fluid....

I still do not have this mower running yet and it is driving me crazy. I looked back at this answer and things are beginning to make more sense. I recently got the mower to run with only the "driver" side plug in and the other side out. That seems almost as if it is timing. What did you mean if it backfired it may have jumped a tooth? This could be the answer or at least a start. Thank you for your help.

I think what 21boat says makes sense. I'm not up on 2 cyl lawn mowers, but if there are two diodes then one must fire on a positive edge and the other on a negative edge, so I'll bet that the cyl with the plug removed has a bad diode. It's firing at the wrong time or twice (positive and negative edge).

Although, this link might suggest otherwise: http://books.google.com/books?id=p3ZHkkm4QU0C&pg=PA162&lpg=PA162&dq=2+cylinder+ignition+system&source=bl&ots=J62rWVaEzE&sig=ukk0EDDU3Ldf4k4VLrs-UnkR4Bg&hl=en&ei=rXsHSoy7F4HOMoaxnKMD&sa=X&oi=book_result&ct=result&resnum=9#PPA162,M1

Look at this and the next page using "page dn"

There is a diode on the breaker points. That may be the problem.

Hence, it would mimic a timing problem.

I reiterate. Never use starting fluid. Use carb cleaner. It's a bit more volatile than gasoline and it contains a lubercant.

I think what 21boat says makes sense. I'm not up on 2 cyl lawn mowers, but if their are two diodes then one must fire on a positive edge and the other on a negative edge, so I'll bet that the cyl with the plug removed has a bad diode. It's firing at the wrong time or twice (positive and negative edge).

Although, this link might suggest otherwise: Outdoor Power Equipment - Google Book Search (http://books.google.com/books?id=p3ZHkkm4QU0C&pg=PA162&lpg=PA162&dq=2+cylinder+ignition+system&source=bl&ots=J62rWVaEzE&sig=ukk0EDDU3Ldf4k4VLrs-UnkR4Bg&hl=en&ei=rXsHSoy7F4HOMoaxnKMD&sa=X&oi=book_result&ct=result&resnum=9#PPA162,M1)

Look at this and the next page using "page dn"

There is a diode on the breaker points. That may be the problem.

Hence, it would mimic a timing problem.

I reiterate. Never use starting fluid. Use carb cleaner. It's a bit more volatile than gasoline and it contains a lubercant.

This answer makes sense. Where is the diode located? I found what may be it on the 2 wires coming out from under the flywheel from the electronic ignition coil.

Is this the diode? It would make sense why the key is all correct, I have fuel, spark, compression but the timing seems off.

Can you add to this as to how to check the diode. Where it would be located? What it would look like etc?

Guessing here: A cylindrical object with two leads probably covered with heat shrink tubing and soldered in series with the wire. Could be somewhere between 1/8 dia to 1/4 diameter and no more than 3/4" long.

Some have a Bullet shape and olthers have a band on them to identify polarity. One band probably goes one way and on the other diode it may be pointing in the other direction. They may be pointing in the same direction too.
When they point in the same direction, they can act as an or gate without interference from the other cylinder.

They usually start with 1N. 1N400? And 1N500? The ? Digit is related to the PRV or Peak Reverse Voltage.

Diodes are usually checked in the diode mode with a multi-meter. One way measures about 0.6V and the other is infinate. If you don't have a diode mode, then check on the lowest scale. If near zero in both directions, it is shorted.

Radio-Shack and some hardware stores sell heat shrink tubing and Radio Shack sells diodes. I can guess what can work. I'm guessing a 3 A 400 or 600 PRV, but a 1 A diode might also work. So 1A 400 PRV is the minimum and a 3 A, 600 PRV would be the most reliable.

Can also guess current by knowing body diameter.

Guessing here: A cylindrical object with two leads probably covered with heat shrink tubing and soldered in series with the wire. Could be somewhere between 1/8 dia to 1/4 diameter and no more than 3/4" long.

Some have a Bullet shape and olthers have a band on them to identify polarity. One band probably goes one way and on the other diode it may be pointing in the other direction. They may be pointing in the same direction too.
When they point in the same direction, they can act as an or gate without interference from the other cylinder.

They usually start with 1N. 1N400? and 1N500?. The ? digit is related to the PRV or Peak Reverse Voltage.

Diodes are usually checked in the diode mode with a multi-meter. One way measures about 0.6V and the other is infinate. If you don't have a diode mode, then check on the lowest scale. If near zero in both directions, it is shorted.

Radio-Shack and some hardware stores sell heat shrink tubing and Radio Shack sells diodes. I can guess what can work. I'm guessing a 3 A 400 or 600 PRV, but a 1 A diode might also work. So 1A 400 PRV is the minimum and a 3 A, 600 PRV would be the most reliable.

Can also guess current by knowing body diameter.

Well I found the diode. It is on the red wire coming from under the flywheel (electronic coil) The diode is black about 1/2" long and 3/8" wide with the letters IN540. It appears to have been fooled with because it is not in the plug well. In fact it swivels easily so how do I know it is in the right way as the current would see it? Your help is greatly appreciated.

http://www.datasheetcatalog.org/datasheet/fuji/1N5407.pdf

There is a digit missing. It's probably, or should be, a 1N5404.

Note hat there is a white band on one side. This side goes away from the coil.

It probably should not swivel. It may have been crimped, but that isn't a good way to make a connection to a solid piece of wire.

Are you able to test with a multimeter?

http://www.datasheetcatalog.org/datasheet/fuji/1N5407.pdf

There is a digit missing. It's probably, or should be, a 1N5404.

Note hat there is a white band on one side. This side goes away from the coil.

It probably should not swivel. it may have been crimped, but that isn't a good way to make a connection to a solid piece of wire.

Are you able to test with a multimeter?

Thank you. You are right the number is 1N5406 and the white band is away from the coil. I can get it tested. What should it read? How do you measure it?

OK, so I'm off on the breakdown voltage. 4 vs 6.

A lot of the multimeters have a diode test mode. In this mode, it passes a small amount of current and reads in voltage. Since it's a silicon diode, it should read around 0.6V and infinite when the leads are reversed.

If your capable of measuring a DC voltage, then a 1k resstor in series with a 9V battery connected to the diode and measure the voltage across the diode in both directions. Again, around 0.6V in one direction and open in the other.

The low ohms mode x1 will be a go/no go test. The diodes usually fail shorted, so if it reads nearly zero in both directions, it's bad.

A 9V battery in series with a 1K resistor in series with an LED connected to the diode will light in one direction and not the other. Again, this is a Go/No Go test.

The resistor, LED, battery clip and 9V battery are available at Radio Shack. 1/4 W or bigger for the resistor should be OK.

http://www.datasheetcatalog.org/datasheet/fuji/1N5407.pdf

There is a digit missing. It's probably, or should be, a 1N5404.

Note hat there is a white band on one side. This side goes away from the coil.

It probably should not swivel. it may have been crimped, but that isn't a good way to make a connection to a solid piece of wire.

Are you able to test with a multimeter?

Well this mower is still not running and I am going to start tours through the jungle since my yard is getting very high... help? I changed the diode and it still does the same thing, it will sputter with the starter as if it is on the verge of running but will not catch and run. It looks possible the timing is off but the key looks fine. How do I verify that the motor is timed with a cylinder at top when the flywheel is on the magneedle? Help I have noticed the one spark plug is new but it is starting to look like it is producing combustion but the other is clean like new.

You know. I think we may have been led astray.

Did you by chance do a valve adjustment on the engine?

I'm not sure of the clearances, but it's normally done with the piston at 1/4" down on the power stroke. Intake and exhaust on that cylinder are done at the same time.

You know. I think we may have been led astray.

Did you by chance do a valve adjustment on the engine?

I'm not sure of the clearances, but it's normally done with the piston at 1/4" down on the power stroke. Intake and exhaust on that cylinder are done at the same time.

No, there has been no valve adjustment. The reason I wonder about the timing is because the "passenger" side piston is down about a half inch when the timing mark on the flywheel is lined up with the left side of the magneedle. I thought the piston should be top of cylinder at that point.

This is definitely something out of the ordinary and is going to require someone really good at looking at the facts to determine which variable is not correct.

The plugs will likely fire at the same time, just one in the power stroke and the other in the exhaust stroke.

That was the premise of 1 coil for 2 cylinders in automotive engines.

The plugs will likely fire at the same time, just one in the power stroke and the other in the exhaust stroke.

That was the premise of 1 coil for 2 cylinders in automotive engines.

So have you ever heard of such a thing as having a 16 hp Briggs that has
1. spark (brand new quick start plugs)
2. fuel (fresh)
3. Compression seems to be good
4. Cranks over good and fast
5. combustion smoke comes out of exhaust

But with all of this it will not run?

If those plugs have the "booster gap" they don't seem to work for standard ignitions.

Get a normal plug.

Sometimes the easiest answer is the right one. Try draining the fuel tank and put in fresh fuel

Hi guys. I have a similar Craftsman with the same model no as being discussed. The one I have runs just fine with the passenger side plug disconnected but won't run at all with the driver side disconnected and PS connected. It acts like it has the power of 1/2 an engine. I cannot find an engine number. But the real question is, does the flywheel have to be removed to find the diode(s)? Thanks for this thread, it surely will help.
Regards to all.

This could still have a weak coil. A little trick to test that is take a good spark plug and cut off the curl part so its now a straight out piece away from the center of the plug. Crank engine, If the spark won't make that bigger jump then it's a weak coil for that cylinder. A spark doesn't mean its 'Hot" enough to run the engine..

Do you have the actual No# of the engine yet.
Model
Make
Type??

Of the engine itself..

I didn't look back on the previous pages but did you check the flywheel "key" If that is off then the timing will be off.

How to check on basic valve adjustments...

http://www.youtube.com/watch?v=j77Y5iwXTzg&feature=PlayList&p=63A0A822C64C8D2D&index=40

http://www.youtube.com/watch?v=hGkn0jR9RJM&feature=PlayList&p=63A0A822C64C8D2D&index=41

Is there fresh fuel?

Do you have the actual No# of the engine yet.
Model
Make
Type?

Of the engine itself..

I didn't look back on the previous pages but did you check the flywheel "key" If that is off then the timing will be off.

******
No I have looked everywhere. All the shrouds are off and I have not seen or felt a number nor have I found a stamped plate.

I have not pulled the flywheel as I am trying to avoid that, but will if req'd

Thanks for the spark plug 'tip'.

Regards to all.

earlgo:

Briggs stamps the numbers on the blower housing and then PAINTS over them. There is no plate.

You will either have to feel for some small depressions or look very closely with a flashlight. Usually it's on the flat portion.

Hi Guys:
In this case the numbers are stamped on the driver's side heat shield on the flange facing front. I took all the shields off and put them aside so I could fix things. This one is a Model 402707 type 0157 02 code 86060512 and someone already said that, so stupid me.

I got both plugs to fire and the engine runs with either plug wire disconnected. However someone put automobile plugs in it: Champion 12Rs. The good news is the radio hardly has any static in it.

I adjusted the needle valve and it starts and idles OK but has NO power. It barely turns the blades and moves in 3rd gear on grass that has been cut 3 or 4 times. When the throttle is opened up all the way it dies. I am thinking plugged fuel filter or junk in the float chamber.

My old but newer 12.5 HP has a lot more power than this alleged 16 HP model.

Regards to all.

Hi guys:
New plugs, the right ones this time, new gas filter, draining the schmutz out of the float bowl, a careful carb adjustment according to the manual, and I am in bidness, as they say.

Thanks for your support and have a great holiday weekend.

One down, one still to go.

Good job!

earlgo If you don't have the manual for your engine I have it for you down the raod.
And the parts to cross reference with

http://www.briggsandstratton.com/maint_repair/manual_and_more/docdetails.aspx?showpdf=272112-DOMESTIC_LO.pdf

http://www.briggsandstratton.com/maint_repair/manual_and_more/docdetails.aspx?showpdf=MS6931_LO.pdf

At least you have more insight on how its all laid out

Getting the engine manual and parts list was easy once I had the number from the heat shields.
What I would like is a copy of the lawnmower manual 917.255821 but even the guy on e-bay with a bazillion manuals doesn't have this one.

If I can get all the heat shields back in place and the lights fixed, I should be set to go.

I can take photos of anything someone needs to see, in reference to this mower, that is. I am assuming that one can link to photos in an on-line photo website.

Regards to all.

You can post pictures using "Go Advanced/Manage Attachments"

Hi guys.
I have replaced the coil with a new one that doesn't use the condenser or points. I cleaned all the schmutz out of all the crevices and the thing starts OK. I adjusted the carburetor as suggested by the manual. When the engine runs it is absolutely necessary to have the choke more than half way out. I do not know if this is normal or not. I have put 8 or so hours on the mower since the repairs and it works OK with the excpetion that the thing needs the choke to run and I don't think it is running at full HP. This is not normal for me as the 12.5HP Craftsman does not need the choke and it runs very strong all the time.
Any suggestions?

Regards,
Earlgo

Baffled240:
The new coil I bought is a part no 394891 and it has all the electronics built right in and is intended to replace the points and condenser and I am assuming the diodes. After being put in the engine started right away. The engine still has to be choked to have any power, but I am working on that. The coil helped immensely but it was $60.
Good luck.

Have you found an operators manual for this tractor? I need a copy! Thanks, Wilson


I have a 16 hp Craftsman lawn tractor 917-255821 that has good spark, has fuel, has compression, has new battery, new spark plugs, has rebuilt carb, has new mag, but will only sputter when cranking but will not catch and run. It ran yesterday for a few minutes but will not restart.
Quick start will not start it. Any ideas...it does not make sense.

No I haven't. There is a guy on e-bay who has manuals for a zillion craftsman tractors but not this one... I asked specifically.
Wish I could find one, too.

Regards,
Earlgo