Shop Products
Houzz Logo Print
amadauss

Briggs 19.5 twin turbo tractor will not start

amadauss
10 years ago

Model 917270821 Cranks but will not kick over. At first I thought plugs and changed those (has two) and then still cranking, thought spray some starter fluid in carb but still would not even kick over a bit with the fluid. Took note no spark in one of the wires. Line was frayed so changed magneto with new one, looks a little different then old one but matches up ok when replaced. Sears service center matched it up. Put it on correctly(Have not checked wires again to see if spark in both thinking brand new). Checked breather on gas cap and its ok. Gas is getting to carb. Not kicking over for that little bit it would do with starter fluid so thinking it has to be something electrical, right? Did get a new carb kit to give the carb an overhaul but have not done that yet. I am recharging the battery right now but always would get a little start with the fluid sprayed in carb so not sure. The grass is getting higher. Thanks.

Comments (58)

  • amadauss
    Original Author
    10 years ago

    Here are a few pictures of the engine compartment. The Model is 42E707 type is 2631 E1 Code is 9805075A
    I put on a new magneto with the two spark plug wires.

    [URL=http://imageshack.us/photo/my-images/11/r9c3.jpg/][IMG]http://imageshack.us/a/img11/7018/r9c3.jpg[/IMG][/URL]

  • amadauss
    Original Author
    10 years ago

    Another picture

  • amadauss
    Original Author
    10 years ago

    one more pic with cover

  • mownie
    10 years ago

    Well, I must admit my sleepy headed mistake in not catching the obvious before I posted last night. I gotta stop checking the forum late night after work!!!!!!!!!
    This is an opposed twin L-HEAD engine...........there are no push rods or valve covers. So let's just forget any references I made in that direction.
    We need to set some terminology straight here.

    CRANKING or CRANKING OVER means only one thing....it means that the engine is being rotated or spun by some external means (a pull rope or an electric cranking motor) so the engine can begin the combustion process and run.

    FIRING means that a cylinder (or all cylinders) is operating normally and producing useful power. A cylinder that is not producing power is said to be "misfiring". Misfiring is also generally referred to as missing. Firing is not a reference to spark at the plug.

    RUNNING is what happens the moment the internal combustion process begins. It is at this point where CRANKING ends. Running is not "kicking over".

    OK, with that behind us, let's see what we can find out.
    If you have been using an ether based "starting fluid"....stop that right now.
    Get a can of spray carb cleaner and spray about a 2 seconds long burst of cleaner into the carb with the choke and throttle wide open.
    Immediately crank the engine. The engine should run for about 2 or 3 seconds on that amount of cleaner.
    If the engine does run 2-3 seconds on each burst of cleaner shot into the carb, you have a problem in the fuel system.

    You say "gas is getting to the carb". That may be true but "gas getting to the carb" does not mean gas is "getting THROUGH the carb" to the engine. The test using carb cleaner will determine whether the engine wants to run but is fuel deprived.

    Ether IS NOT suitable for use in this genre of engine except in ambient temps near ZERO degrees F.
    At higher ambient temps it is too explosive and can cause engine damage including cracked pistons and/or broken piston rings.

    This post was edited by mownie on Wed, Aug 21, 13 at 12:13

  • amadauss
    Original Author
    10 years ago

    Thank you so much for the response. I did pull the plugs and had my son crank it and I was definitely feeling compression in the holes. I will try the carb cleaner which I have right now and post results. Thanks again.

  • amadauss
    Original Author
    10 years ago

    No luck with spraying the carb cleaner. Gave it a couple of shots of the cleaner and just cranks away. No start. I did use that starter fluid spray a few times before this so, could the carb be gunked up a bit from it? I gave the carb another spray of the cleaner and thought give it an hour or so and then go try to start it again by spraying for 2 or 3 seconds and then cranking it. I had changed the gas filter beginning of this season but maybe need to do it again. Any suggestions appreciated.

  • amadauss
    Original Author
    10 years ago

    Tried it again and no luck. Just cranks and does not start. I did already have a carb overhaul kit I bought a couple of months ago to work on the carb as preventive maintenance and thinking maybe need to do this, Kit number is 694056 made for my tractor. I also checked the gas line and it looks like there is gas flowing to the carb. Thanks

  • walt2002
    10 years ago

    Well I will go against what I said. Thanks Mownie for getting thing straightened out.

    You installed a coil. Did you install it correct side up? The plug wires exit the coil heading towards the "back" of the engine then turn and double back under the coil and come out on the spark plug side of the engine.

    Walt Conner

  • walt2002
    10 years ago

    I see in the pictures that the plug wires are routed correctly indicating correct coil installation BUT the coil looks odd to me for that engine.

    Walt Conner

  • mownie
    10 years ago

    If the engine does not try to run on the carb cleaner sprayed into it as described, the issue is not due to a lack of fuel.
    So it comes back to what you stated earlier about going to Sears for the magneto and ***" Sears service center matched it up."***.
    And Walt says it looks odd for that engine. (Walt is the go to authority on these opposed Twins).
    So, what is the part number of the magneto Sears sold you?
    The correct Briggs part number for the magneto that fits your engine is 394891. This number also is the same number used by Sears in their owners manual parts list. If the number they sold you is not 394891, you may have bought a magneto for an older version of opposed Twin, and it might not be compatible with your version of Twin ignition system.
    You said you were going to check for spark, have you done that yet?

  • tomplum
    10 years ago

    That actually is the new style Briggs coil- since late last summer.590781 is the new OPTW coil #.

  • amadauss
    Original Author
    10 years ago

    Thanks all for help. Will go and look for spark again to make sure it is there. And you are correct Walt, it does not look like the old one but they must have decided on new style, correct? Here is a pic of the box. Went to look for a number on magneto but their is none. It also looked a little strange on top of box with the part number being erased which is correct and then someone puts a new number on and scribbles that out and lists the correct number again. Also had this wire which my guess is the kill switch connection which I did not need because just plugged in original. Would that be an issue? And that little piece which it stated on a slip of paper in the box to use if you had something else you did not need anymore, condenser maybe? Cannot find the paper. Showed where to put that part in small picture on it.

  • amadauss
    Original Author
    10 years ago

    Picture of wire and part.

  • amadauss
    Original Author
    10 years ago

    Here are some pictures of the old magneto. I wrote ground on one of them thinking does the magneto need to be grounded? I thought maybe that other connection would do this. Did not see a little screw on the new one to attach that new wire to.

  • amadauss
    Original Author
    10 years ago

    2nd picture

  • amadauss
    Original Author
    10 years ago

    Top of magneto which would show when looking at engine.

  • amadauss
    Original Author
    10 years ago

    Pulled the plugs and left them attached to the wires and held them near metal on the engine and they were both firing away so not the plugs.

  • rcbe
    10 years ago

    What gap do you have those plugs set at?

  • walt2002
    10 years ago

    Thanks Mownie however I no longer work on them nor much of anything and was not aware of the change in coil.

    Walt Conner

  • amadauss
    Original Author
    10 years ago

    Not sure on gap rcbe, just took them out of the box and put them in. Would the gap not allow it to start even firing the way they seem to be doing? I'll pull the manual, what gap should they be? thanks

  • mownie
    10 years ago

    Spark plug gap is .030". Spark plugs right out of the box will generally spark well enough for the engine to run on, unless the electrode gap has been completely closed up because of rough handing (dropped) during shipping. And that should be all too obvious because the packages nowadays will have to be pretty banged up for that to happen.
    This is a very puzzling case. Most unusual!
    Testing for spark if you just lay a spark plug on a surface of the engine OUTSIDE of the combustion chamber (instead of threaded into the spark plug hole) is not recommended as a means of absolute proof that the plug is actually sparking when it is inside the combustion chamber and under compression conditions. Briggs recommends that you only use their version of a spark tester that connects inline with the spark plug and spark plug cable and tests for spark while the plug is threaded into its normal location. This way the effects of compression are accounted for. The Briggs tester is part number 19368.
    But, I think it might be a good idea to try starting the engine with the kill wire disconnected from the magneto.
    BEWARE, if you do this with the fan shroud removed, and the engine starts and runs....the engine will overheat without the shroud in place. and you will have to kill the engine by other means (such as smothering it with the choke and maybe a rag placed on top of the carb).
    If the engine starts and runs with the kill wire disconnected, the electrical characteristics of the kill wire circuit are gonna need a very thorough testing and inspection.
    I am taking a wild shot here because the engine ought to be running as it SEEMS to have spark and we know it has fuel (albeit in the form of carb cleaner).
    My thinking along this line is that there may be a "bleed path" or leakage somewhere in the kill wire circuit (key switch, deck switch, brake switch, or seat switch, or any of that associated wiring) that is killing the effective spark enough that the magneto can't spark the plugs when they are under compression, but does allow for a weak spark outside the combustion chamber.

    The kill wire circuits could be tested using an Ohmmeter.
    One would need to understand the function of each switch involved in the safety interlock system (as to when each switch opens the kill wire circuit) to determine whether a switch (or a damaged section of wiring) was bleeding enough continuity to kill spark under certain conditions.
    The trouble might even be in the section of wiring that travels across the engine under the shroud.

  • amadauss
    Original Author
    10 years ago

    Hi and thanks for response. If you take note on my 5th or 6th post, I pulled the kill wire off the new magneto and tried to start it and it just cranked away with no start. I can go get the Briggs tester and try it in the morning. My guess would be the sears service center has it but they are already closed as I write this. I am glad you mentioned the fan shroud which I did not have on when I tried to start it with out the kill switch connected. I was not aware that if started the key could not then turn it off with kill switch disconnected. Probably would have had a panic attack.

  • mownie
    10 years ago

    OK, yeah, I went back and read it and I see you tried to start it like that.
    I thought I read where you just checked for spark with the kill wire off.
    Have you looked down the throat of the carb with the choke set at wide open (choke is OFF)?
    Look down the carb throat with a flashlight and see if the throttle plate is standing wide open when you have the throttle control moved to the highest speed setting.
    The throttle plate is the second "flapper" deep in the carb, the choke is on top of the carb.
    If the throttle plate (aka "butterfly") is shut instead of wide open, that would be a reason for having spark and fuel, but no run.

  • amadauss
    Original Author
    10 years ago

    That is it Mownie!. I moved the throttle wide open and it is staying in the same position as the choke would be if engaged all the way, Flat. I never even realized that plate should be open to run. I am going to take some pics and post in a few minutes and maybe you can suggest what is not working. thank you so much!

  • amadauss
    Original Author
    10 years ago

    choke opened and with the throttle control on all the way the piece below choke is still closed.

  • amadauss
    Original Author
    10 years ago

    Here are the parts under carb that control the throttle to work or not. Do I need to adjust any of these or do I have to take the carb apart to get it to work. I am going to look around for something not connected correctly. Thanks again and hopefully you can see it.

  • mownie
    10 years ago

    (Whew!) OK, be sure you get some pictures showing the linkages and springs that (are supposed to) connect the carb throttle plate lever to the governor.
    EDIT. I see (after I initially posted) that you have pictures up.
    Unfortunately it is Saturday morning and I am at the beck and call of wife. And she just beckoned and called and so I have to run a few errands for her...........I'll be back shortly and peruse the pics.

    This post was edited by mownie on Sat, Aug 24, 13 at 11:09

  • amadauss
    Original Author
    10 years ago

    Here is what you wanted I think.

  • amadauss
    Original Author
    10 years ago

    Here is another. Will get a few more. The metal wire control inside the plastic wrap of the throttle control is working and moving everything. Either the flap is just stuck somehow or one of the controls is missing a connection on the outside connecting one to another to move that part is my guess but not sure. will take some more pics.

  • amadauss
    Original Author
    10 years ago

    Another pic

  • mownie
    10 years ago

    OK, 1 errand down.
    Get another pic of the scene below, but move back away about 10" so the scene encompasses more of the mechanism.
    (good pictures, by the way).

  • amadauss
    Original Author
    10 years ago

    How is this. Looks like I need a gasket off of that one exhaust or maybe the bolts just need to be tightened. Thanks for the help, especially on the weekend.

  • amadauss
    Original Author
    10 years ago

    one more just in case.

  • amadauss
    Original Author
    10 years ago

    and a side pic just backed up a bit.

  • amadauss
    Original Author
    10 years ago

    another side pic. a little out of focus but I hope it helps.

  • amadauss
    Original Author
    10 years ago

    Those last pictures after you requested I back up are with the throttle completely disengaged so turned off.

  • amadauss
    Original Author
    10 years ago

    Ok, wife going nuts about the grass so I thought if that throttle is stuck has to be something simple. So I tried to wiggle a couple things and took the end of my screwdriver and taped on that part on the carb that would control the throttle. Moved and opened up so it worked. Made sure the throttle control could control it and it did no problem. Went to start it and started right up. A lot of blue smoke, coming from that side that shows the oil leaking on to the exhaust pipe. Also if you take note on the picture it is leaking some oil on that side a little bit. Also, took note when I went to change the plugs the old one on that side of engine was a little wet and black compared to the other one.
    When I did get the throttle to move and it opened I looked down inside and I have a lot of black gunk laying on the bottom. Definitely needs to be cleaned so thinking after I cut the grass, might try to take it apart but not sure. Would the carb cleaner get rid of that stuff if I sprayed it and then started the engine and let it run? Plan is to cut the lawn in the morning after it dry's up a bit. Thank you for your help.

  • mownie
    10 years ago

    OK, good you got it unstuck.
    It looks like your idle stop screw and the coil spring are missing from the carb.
    Note the red arrow in the image below pointing to a vacant, threaded hole. In that hole there should be a slot head screw with a coil spring around the screw. The screw is the "idle stop" screw which actually sets the low idle stop point for the throttle plate bellcrank. The screw makes certain that the throttle plate is "jacked open" enough to permit the carb idle circuits to operate.
    Without the screw in place, the throttle plate bellcrank is permitted to roll back too far and apparently, the throttle plate is either STICKING in place from some gunky stuff on the edges of the plate, or else the bellcrank is "camming over" and locking because the stop screw is not there to prevent it.
    Here is what I am finding as to part numbers for the parts.
    From Sears...Idle stop screw part # 91920, spring part # 261607.
    From Briggs...Idle stop kit with screw and spring part # 807923
    The screw adjusts the low idle RPM stopping point, the stiff coil spring simply places enough tension against the screw threads to keep the screw from vibrating and self adjusting (and falling out). I suspect that the screw had previously been backed off too far and the spring became ineffective at holding the screw, so they both fell out and disappeared.
    And this entire revelation brings up another aspect of idle speed. Normally, idle speed is set by this screw preventing the tab on the throttle bellcrank from coming back too far, which kills the engine.
    I believe that the throttle cable on your machine has been adjusted improperly and may be pulling the throttle open very slightly instead of letting the stop screw keep the throttle from falling back against the kill threshold of the plate.
    Or in other words, without an idle stop screw to maintain a low idle RPM point, the idle position has been done by the throttle cable acting on the governor linkage.
    I would think that an engine operating without an idle stop screw would also be prone to an uncertain idle......like maybe it idles some time and maybe again it will die.........or it just idles too fast most of the time.
    Any of that sound like you?
    I will post a picture of my own Opp Twin carb linkage showing the idle stop screw and spring.
    If there is a way to post multiple photos to a single post I have not figured it out yet.

    This post was edited by mownie on Mon, Aug 26, 13 at 12:29

  • mownie
    10 years ago

    A big ole picture of the idle stop screw and holding spring.

  • tomplum
    10 years ago

    Wow, lots of op twin porn here. Are we up and running yet?

  • amadauss
    Original Author
    10 years ago

    Mownie, thanks so much, it all sounds like me with the idle. I need to get that part first thing tomorrow. Service center is closed today. How about the gunk on the bottom I mentioned. If I spray some carb cleaner will it burn itself away or should and do I have to give it a cleaning now by taking it apart? Seasonal here so stop cutting in October sometime usually. Should I wait until then to take it apart as a project over the winter? And the dirty plug on that one side, what do you think there? Thanks again so much. Hope you got your errands done. And you are right about the pictures. Tried but could only post one at a time. I even tried to put a link onto my message from a site that holds pictures for posting but when I tried the message said it had an error. Thanks again!

  • mownie
    10 years ago

    Well, the gunk in the bottom , while unsightly....is not something that needs immediate attention.
    I would wait until the mowing season was finished before tackling that job. That crud is mostly caused by the typical spit-back through the intake valve that is characteristic of the Briggs easy spin decompression system. I have covered this subject in other threads and will only say here that Briggs that use the easy spin camshaft will spit back through the intake and carburetor some at low RPM. At operating RPM the spitting is barely there.
    It typically requires some brushing and spraying with spray carb cleaner to accomplish the clean up. Best if the manifold is removed from the engine so you can clean from the head ends as well.

    In the mean time, put a drop of oil on each pivot point in the carb and governor linkage.
    When you get the idle stop screw and spring installed, you want to set the idle RPM by adjusting the idle stop screw, so we may have to get into that too.

  • amadauss
    Original Author
    10 years ago

    sears service center is getting me the parts. Should have them by Wednesday. Will post after I install them. thanks again.

  • britcar
    10 years ago

    Mownie sounds like the one who can help me with a very similar problem. This is what I posted on another forum , but have not received any replies: Model 271022 has the Kohler 15.5hp CV15S and model 727810 has the B&S twin 42E707 19.5hp. Kohler began shutting down and eventually backfiring when trying to restart. I cleaned the carb, changed the plug and checked the coil. Found the coil was in spec, but no spark. Disconnected the kill wire, had spark and was able to start it one time. Second attempt a while later and it wouldn't even turn over, nothing. Checked wiring for breaks all looked good. Checked safety relays both good. Checked starter switch, good. Jumped between solenoid terminals, engine will crank. Now the kicker. The B&S did exactly the same thing 2 weeks ago. Was able to crank over one time then the same as the Kohler. What am I missing? Something in the safety wiring? Any suggestions most appreciated. Am I living over an old burying ground?

  • rcbe
    10 years ago

    britcar - start a new thread. this one is getting long in the tooth.

  • britcar
    10 years ago

    Sorry.....started new thread as: Craftsman B&S 19.5 and Kohler 15.5 Won't Start

  • HU-407961074
    3 years ago

    I have similar problems as the above mower. Mice at threw the spark plug cable thus making me replace the magneto. I ordered one from Walmart and sent it back non working. I then ordered one from Amazon. I pulled the flywheel off and clean out from underneath it. It was filled full of dirt and grass. Blew everything out and reassembled it. Installed the new Magneto and it fired up. We put it back together and tried starting it. NADA. I now have the machine apart again and pulled the magneto to check the continuity. NADA. I am thinking that the coil being recommended is wrong. Model 42E707 Type 2631 code 9802205B.. If you can please advise right coil for this machine. Thanks

  • bluemower
    3 years ago

    hello HU-407961074


    I am not going to read through all the comments above. Hope you have tried their suggestions.



    This is long.

    The original part number is 394891.

    B&S changed the part number to 590781 when they switched to a chinese supplier. The retail price for this item is close to $60.00. All the cheap armature ignitions on the internet may work ok, but I don't know.


    The original ignition seldom fails. Mice destroyed your sparkplug wires. Another failure occurs when the key switch fails and voltage is introduced into the armature coil shut off wire. When the key is turned off, the shutoff wire should be connected to ground only. Any voltage will instantly destroy a new armature coil. Corrosion on the mounting post and mounting screws is another problem that will cause loss of ignition. A shorted shutoff wire will also cause a problem.


    When installing a new armature coil, clean the mounting post to insure a good connection. A small wire brush will work fine. Make sure there is no corrosion on the armature laminated stack. The mounting screws must be clean.


    Direction of installation is marked on the armature coil. With the armature pulled away from the flywheel, tighten the screws. Rotate the flywheel until the magnets are next to the armature. Install a spacer (.008 - .012) between the armature and the magnets. A business card will usually work. Loosen the screws and the armature will be attracted to the magnets. Tighten the screws. Remove the card by rotating the flywheel. Feed the ignition wires to the sparkplugs but do not install. Leave the shut off wire disconnected. Connect the sparkplug leads to an air gap ignition tester. The tester should have a .166 gap. Approximately 13,000 volts is needed to jump the .166 gap. If you do not have the proper tester, make your own. Connect the ignition tester to the engine block - not the spark plugs. NOTE: The glow light ignition testers do not always work well, so do not use. These will glow at a voltage too low to start a small engine. You can test for ignition now - even with the blower shroud removed. You will need to hold the oil filler in position so it does not blow out. Care is needed with a rotating flywheel.


    Look at the spark tester for ignition. A spark can be blue, amber, or invisible. A darken area may be needed when performing this test. Before connecting the shut off wire, you must insure the key switch is not feeding voltage and that the off position connects to ground. Install the blower shroud.


    Sparkplugs may have carbon or oil on the porcelain. This may form a carbon trail for the voltage to follow and you will never see a spark. A crack in the porcelain will also cause loss of spark.


    If your flywheel key is sheared, the engine may not start due to incorrect timing, however you should still have spark.


    If the engine does not start after ignition is restored and timing is restored, ask questions.

  • Donnie Smith
    2 years ago

    Can some one tell me why my 19.5 briggs stratton year 1996 does not want to turn over like the battery is low.If I let it sit 7-8 hours It will spin and start.I can let it run 30 seconds then it will not turn over,its like the battery is low. I run two batteries at the same time still does it.I was told to reset the valves but there are no rocker arms.The valve stems go into the block next to the piston.Both sides.Any one have any ideas.

  • bluemower
    2 years ago

    hello Donnie Smith

    probably should have started a new message to get more responses. I suspect you have an old opposed twin. The engine numbers are located on top of the engine blower shroud. Look for a small plate that is riveted to the shroud. This contains (1) model, (2) type, and ((3) code.


    maybe the batteries are the problem. A load tester can verify battery condition. Some of the auto parts shoes can help if you do not have a tester. Be careful not to connect battery wires backwards. If you have a volt meter, You can ask a helper to monitor battery voltage while the engine is being cranked. A good battery will maintain 10 1/2 volts to 11 volts while the engine is being cranked. To perform a quick test, try attaching a positive jumper cable directly to the starter motor post. The ground cable can be attached to a metal part of the engine briefly to see what happens. If you try this, be ready to remove the ground cable quickly. This test bypasses all the tractor wiring.


    There also be problems with all the connections to the battery , starter solenoid, starter stud, and the engine mount bolts. All these points may loosen or form corrosion and continuity is lost. Knowledge and use of a volt meter is needed to test. The starter motor may also have a failure developing. Valve adjustment may be a factor, but this condition is not likely on a flathead. The opposed twin does not have a compression release device, but relies on the old easy spin profile on the camshaft. On a flathead, wear in the valve train tends to decrease the valve clearance and this results in less compression. A sudden stoppage may cause the flywheel key to partially shear resulting in advanced ignition timing. Again, this is not likely since an engine this size is usually mated to a rider and does not normally experience sudden stoppage. Normal cranking compression on the opposed twin is probably around 115 psi. I live at 7,200 feet and compression is usually around 95psi. If the engine has been run with low oil quantity, the bearing may have seizure issues. Remove the sparkplugs to see if the engine rotates easily by hand. Also try running the starter while the plugs are removed.

    If you are not a motor person, these checks may be too challenging and a visit to a small engine shop may be needed.

Sponsored