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Briggs 19.5 twin turbo tractor will not start

Posted by amadauss PA (My Page) on
Tue, Aug 20, 13 at 14:00

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.


Follow-Up Postings:

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RE: Briggs 19.5 twin turbo tractor will not start

I had a problem with my tractor something like that. It would crank but not fire up: not even a hiccup. That yours is cranking pretty much rules out safety switches, as it did on mine. Mine turned out to be a bad ignition module. John Deere found that out. How to check it yourself: I have no idea.


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RE: Briggs 19.5 twin turbo tractor will not start

I just charged the battery and then checked both plugs for fire and they are sparking when trying to start engine. But still will not crank over. Spraying starting fluid in carb without it cranking over for just a few seconds scares me. maybe the carb? Also the magneto I refer to is the ignition module I think which I replaced with a new one. I used the business card trick to align it so hoping that is ok.

This post was edited by amadauss on Tue, Aug 20, 13 at 17:56


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RE: Briggs 19.5 twin turbo tractor will not start

any chance you have a sheared (or partially sheared) flywheel key throwing yer timing off?


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RE: Briggs 19.5 twin turbo tractor will not start

When I took the cover off to install the ignition coil I took note to the flywheel key (the plastic piece with teeth, correct?) which I have also replaced recently and it looked ok but did not give it a good inspection. Will do so in the morning. I remember the teeth being all messed up before I changed it and it still started. The main flywheel is turning when I turn the key and everything seems to be working, just will not kick over.


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RE: Briggs 19.5 twin turbo tractor will not start

Also wanted to note I did pull off the kill switch on the new ignition coil to see if that was faulty and tried to start but with same results. No go.


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RE: Briggs 19.5 twin turbo tractor will not start

***" took note to the flywheel key (the plastic piece with teeth, correct?"***
No, that is not correct.
The flywheel key is a small metal plate kind of thing that fits into a slot in the center bore of the flywheel and a matching slot in the crankshaft taper.
If you are not aware of this key and its function then it is possible you have left the key out.
Even if you did put the key in, and you did not use the proper method to insert the key, and or you did not properly torque the flywheel retention nut.............the key may be sheared by now.
But this would not explain why the engine would not run BEFORE you changed one of the mags.
Get rid of the starter fluid, save it for your big diesel engine powered truck. Spray can of carb cleaner is safer for the engine and will give results similar to gasoline when sprayed into the intake as an alternate type of test fuel.
Engine is model 42E707.
Check for compression on each cylinder by placing a thumb over the spark plug hole while a helper cranks the engine.
If you find a cylinder that seems to have little compression, remove the valve cover on that cylinder and inspect for a bent or out of place push rod.


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RE: Briggs 19.5 twin turbo tractor will not start

Well a 19.5 hp B&S and "Installing THE coil," does not sound like an OHV engine. The terminology is such a mess and with no engine model number, I will leave this alone.

Walt Conner


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RE: Briggs 19.5 twin turbo tractor will not start

Thanks so much Mowie, will do and post pics with results. Sorry Walt for terminology, will correct in all posts coming. Thanks for just taking a look, appreciate it.

This post was edited by amadauss on Wed, Aug 21, 13 at 8:42


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RE: Briggs 19.5 twin turbo tractor will not start

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]


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RE: Briggs 19.5 twin turbo tractor will not start

Another picture


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RE: Briggs 19.5 twin turbo tractor will not start

one more pic with cover


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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?


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

Picture of wire and part.


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

2nd picture


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RE: Briggs 19.5 twin turbo tractor will not start

Top of magneto which would show when looking at engine.


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

What gap do you have those plugs set at?


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RE: Briggs 19.5 twin turbo tractor will not start

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

Walt Conner


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

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!


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

(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


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RE: Briggs 19.5 twin turbo tractor will not start

Here is what you wanted I think.


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

Another pic


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RE: Briggs 19.5 twin turbo tractor will not start

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).


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

one more just in case.


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RE: Briggs 19.5 twin turbo tractor will not start

and a side pic just backed up a bit.


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

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


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A big picture Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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!


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RE: Briggs 19.5 twin turbo tractor will not start

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.


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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?


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RE: Briggs 19.5 twin turbo tractor will not start

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


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RE: Briggs 19.5 twin turbo tractor will not start

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


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