Hello. I have a question about the test port on the electrical system. The manual shows it but does not say what it test for. I have tried a DVM and there is no voltage on it. There is continuity between the port and ground.
I am trying to find out why I have no spark. The tractor has just had the valves adjusted. When I started it it ran fine until I went to back out of garage it stopped. It has not ran since.
Any help will be appreciated.
Jeff
Test port? Never hear of a test port on a mower. Are you grounding the spark plug to the engine when checking for spark?
Many lawn mowers will have an empty connector and you're probably thinking in an automotive sense but unless you have a fuel injected small engine you will not find a test port like you would on a truck. Have you tried a new spark plug...could simply be this! FYI, on a typical lawn mower, the only safety switch related to the kill circuit will be the seat switch.
Originally Posted by puey61
Many lawn mowers will have an empty connector and you're probably thinking in an automotive sense but unless you have a fuel injected small engine you will not find a test port like you would on a truck. Have you tried a new spark plug...could simply be this! FYI, on a typical lawn mower, the only safety switch related to the kill circuit will be the seat switch.
Actually the PTO switch is on that seat switch circuit and on some there is also one on the brake to allow you off the seat with motor running as long as blades off and brake on. OP could explain 'not ran since' with more specifics
Actually, the PTO and clutch/brake pedal switches are on the start circuit, not the kill circuit.
The pto and clutch switches will not keep it from sparking. The seat switch is the only one that kills spark. The clutch and pto switches only keep the starter solenoid from working. If the clutch is pressed and the pto is off, then the seat switch won't even be able to kill the spark. I doubt it's a switch problem though.
Oops, Puey beat me to it, someone came to my door while I was replying.
Thanks for all the help. To clarify the manual shows a test point connected to the seat switch. On the mower it is a extra connector coming off the seat switch. It is a yellow wired with a female connector on it.
I made sure the spark plug was grounded and I also tried a new one.
As far as never ran again I meant that when I started to back up the engine died and I have not had any spark since. I did remove the seat switch and tested it. It worked ok. I am going to remove the PTO switch today and check that.
I would really like to know about the electric test point as it may save me a lot of time. I think using the word port through some of you off track. It is an electrical test point.
Thanks again for all your help.
Jeff
The rider is Sears model 536.270320 13.5 HP electric start 30 mulcher/ mower hydrostatic drive. I tried to post a picture of electric system but could not figure out how.
In addition there seems to be no power to the seat switch. I checked all the connectors with a volt meter and got nothing on any of them.
Thanks
Jeff
There should be no power to the seat switch. Disconnect the kill wire from the coil and see if you have spark. If not, you have a bad coil.
Originally Posted by cheese
The pto and clutch switches will not keep it from sparking. The seat switch is the only one that kills spark. The clutch and pto switches only keep the starter solenoid from working. If the clutch is pressed and the pto is off, then the seat switch won't even be able to kill the spark. I doubt it's a switch problem though.
Oops, Puey beat me to it, someone came to my door while I was replying.
Sorry guys but you are only half right. Yes it's may be the seat switch that grounds the coil and kills the spark but that circuit does go through both a pto switch and on MTD the brake switch. Both those switches are double ones. One side is N/O and the other N/C. One is in the start circuit to the solenoid and the other in the coil to seat switch circuit.
I am very aware that the circuit passes through the other switches, however, those other switches do no kill spark. If those switches fail, open or closed either way, they will not kill the spark. So they are irrelevant to the operation of the ignition system. You do not test pto and clutch switches in order to diagnose ignition problems because they have nothing to do with it. Why do you insist on placing importance on switches that have nothing do with the the problem in this post?
Thanks again for all your help. I disconnected the kill wire and I had spark. Then I tested the kill wire and it is not grounded in the run position. I started the tractor and it ran again for about 20 seconds and quit. When I crank it now it backfires trough the carb. I am just at a loss now. I removed the valve cover to make sure the valves had not come loose again and all was ok.
When I try to crank now it will crank but if it were a car I would say it was out of time. It bucks and fires through the carb.
I know I have asked a lot of questions and I have also learned a lot. I thank you all for the help in my quest.
Jeff
Have you had the flywheel off? Could be a sheared flywheel key or a bad spark plug.
Originally Posted by cheese
I am very aware that the circuit passes through the other switches, however, those other switches do no kill spark. If those switches fail, open or closed either way, they will not kill the spark. So they are irrelevant to the operation of the ignition system. You do not test pto and clutch switches in order to diagnose ignition problems because they have nothing to do with it. Why do you insist on placing importance on switches that have nothing do with the the problem in this post?
How about the possibility that the circuit from the coil at the pto switch connection is grounding out or maybe has come off the switch connector and is lying on the metal chassis or the switch ,although N/O, is defective, and grounding out to it's metallic mounting? Gee, then there is no spark, exactly the problem of the OP. There is a circuit for that kill and the whole circuit needs to be verified, in my opinion.
Jeff,
Don't hesitate to ask questions, that is exactly what we're here for.
38racing, this is just getting old. That would be a wiring problem, not a defective switch. No need to go through the entire related wiring system just to diagnose a no-spark condition in 99% of cases. That is something you do late in the diagnostic procedure, if every other test has been inconclusive, not right at the beginning when you first discover there is no spark. The point still remains that those switches do not control spark and their failure will not kill the engine. I'm not interested in arguing about it anymore. If you can't admit you're wrong, that's fine, but don't call us wrong and force false information here.
Originally Posted by cheese
Jeff,
Don't hesitate to ask questions, that is exactly what we're here for.
38racing, this is just getting old. That would be a wiring problem, not a defective switch. No need to go through the entire related wiring system just to diagnose a no-spark condition in 99% of cases. That is something you do late in the diagnostic procedure, if every other test has been inconclusive, not right at the beginning when you first discover there is no spark. The point still remains that those switches do not control spark and their failure will not kill the engine. I'm not interested in arguing about it anymore. If you can't admit you're wrong, that's fine, but don't call us wrong and force false information here.
Agreed , end of discussion, but I resent your statement that I am wrong and NOTHING I just posted was FALSE, just not where you would look initially.
When I first starting out I removed the flywheel and the key was good. I will try a new spark plug. Thanks Cheese.
Jeff
I'll bet you did not properly torque the flywheel nut after your inspection of the key and you NOW have a sheared flywheel key. Briggs part number 222698S for the key and since you didn't post the engine ID numbers but you noted it was a 13.5-horse Briggs you likely have a single-cyliner, 28-cubic inch engine and, with such, flywheel nut torque will be 85 foot pounds. If you torqued anything under about 65 foot pounds you are sure to have sheared the key. FYI, the key controls ignition timing.
Thank you for the advice. The engine number is 21B807-0326-E1. I am guilty of not using a torque wrench. I have gotten away with it but not on this large an engine. I removed the fan and cover and flywheel bolt and sure enough the key is sheared. It went almost half the way around and now using my puller I have not been able to get it off. I will let it sit with pressure on it and try again.
The Briggs and stratton repair book I have only list one 28 cu. in engine but they are saying 95-100 lbs torque. The book calls it a power built. The book is by Paul Dempsey
I appreciate your help. I will get a key and buy a torque wrench.
Jeff
Tighten the puller then whack the flywheel with a hammer enough to shock it loose. Hit it on a flat area on top but not so hard that it breaks something.
Your flywheel nut torque is 100 foot pounds. You'll also need a strap wrench or other suitable device to hold the flywheel in order to torque it to the 100 pounds that you need to go to! Otherwise you'll never achieve that torque.
Thanks for the reply. Since I do not have a strap wrench or a torque wrench I will have to buy them the problem is they are over $150.00. I will have to wait awhile.
They say there is no such thing as a dumb question so here goes. Could I use an impact wrench. I have one I use to remove tires.
Jeff
Yes, you can. I don't know how powerful the impact is (they range widely in abilities), but the times I've used one I just let it chug a few seconds to get it as tight as it could. The exact torque amount is not critical. The main importance is that the bolt gets tight enough. Do not allow oil or grease to be on the mating surfaces of the crankshaft and the flywheel either, or it will shear again.
A 1/2 impact wrench will be needed to get you close to 100 lbs but, more importantly, an air compressor with at least 150 psi along with your 1/2 impact will be needed. If you're going to use a homeowner compressor with a 3/8 drive impact you'll be replacing another key. If you don't have these tools it might be best to load it on your truck and let someone with the right tools torque it down.
I am really impressed with this forum. I have learned many things in the last week or so.
I followed the advice about using a impact wrench to tighten the flywheel puller. First I ground the bolt head round so it would clear the socket and go on the nut. When I applied the impact wrench it popped loose easily.
I am also going to take the advice about using the impact to tighten it. I have a compressor and a 1/2 in drive wrench.
I am dead in the water now waiting on a key. I will report back when I get it all back together again. Once again than you all for you help.
Jeff Schock
WB9ZPO
All small engine shops and many hardware stores carry the key. Lowes even sells them or did at one time if I recall correctly. Use the right kind of key though, not steel keystock or you risk damage and/or injury if it ever has to shear again.
Installed key and tightened flywheel with impact wrench. Running fine.
It would have never happened without the help you all gave me.
Once again thanks.
Jeff
PS Final post on this subject.
Great, glad we could help. Did you ever pinpoint the no spark problem?
Originally Posted by cheese
Great, glad we could help. Did you ever pinpoint the no spark problem?
Not really. Since I had all the switches out to check I figures that one of the malfunctioned but when cycled several time it worked.
No one ever did answer my original question about the test port. Not important now but I am still curious.
Thanks again for your help.
Jeff
I have no clue why they would call it a test port. There is little to be tested by it. I don't recall what part of the circuit it is tied to but it has no purpose for diagnostics as far as I'm concerned. Might just be something they use at the factory during assembly to verify that some connection is made.
This is my response from early in the thread:
Originally Posted by puey61
Many lawn mowers will have an empty connector and you're probably thinking in an automotive sense but unless you have a fuel injected small engine you will not find a test port like you would on a truck. Have you tried a new spark plug...could simply be this! FYI, on a typical lawn mower, the only safety switch related to the kill circuit will be the seat switch.
Sorry I remember you replied. I was still curious because the empty wire is show on the electric diagram in the owners manual as test port.
Thanks again for your help. I will forget about the wire for now.
Jeff
Ok and thank you.
Jeff
Tags: mower, electric, question, seat switch, spark plug, clutch switches, kill spark, Originally Posted, impact wrench, test port, those switches, will have
