B&S 12 HP - No Spark

Discussion in 'Mechanic and Repair' started by hdtvluvr, Jun 24, 2007.

  1. hdtvluvr

    hdtvluvr LawnSite Senior Member
    Messages: 512

    OK, I finally gave up on repairing my old engine (11 HP B&S) and found a new 12 HP one (284707, 1026E-1, 030618ZE). This new engine had a a dual circuit alternator and I needed to use the one off my old engine since my mower had an electric clutch.

    I removed the flywheel (using a steering wheel puller - Thanks for the help Restrorob), replaced the alternator and put everyting back together. I torqued the flywheel nut to 65 ft. lbs using a torque wrench.

    In my haste to to get the enging back on the tractor, I used an electric impact wrench to tighten the shaft bolt that holds the electric clutch. I heard a "tink". I assumed it was the bolt breaking but everything is mounted solid. I continued connecting all of the wires, etc.

    When I tried to start it, it wouldn't start. I checked for spark using a spark tester and there wasn't any. OK, I figured the "tink" may have been the flywheel key so this morning, I took the cover back off and checked the key. It looks solid and the groove in the shaft is lined up with the groove in the flywheel. I did not move the coil when I removed or reinstalled the flywheel.

    Any ideas what the "tink" may have been? What do I need to check to find out why there isn't spark?
  2. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    Even if the key is broke you'll still have spark. Maybe not at the right time - but still will spark. Sounds like maybe the kill wire from the coil is connected wrong. Disconnect all your wiring to the engine and test for spark.
  3. LindblomRJ

    LindblomRJ LawnSite Silver Member
    Messages: 2,570

    Check the kill wire first on a no spark condition. Just went though that earlier this week on one of my mowers.
  4. hdtvluvr

    hdtvluvr LawnSite Senior Member
    Messages: 512

    I don't have time to put everything back together tonight and test for a spark. However, I did take a photo of the kill wire connection. I'm not sure what the short wire is for. It wasn't on the other engine.

    Well, I can't seem to upload the file right now. I'll try later
  5. hdtvluvr

    hdtvluvr LawnSite Senior Member
    Messages: 512

    Well, for some reason the photo won't uplaod. It is smaller than the max size limit and is about 170K.

    The photo shows a black plastic insert to the left of the throttle cable. This is where the coil wire is attached. I added the white wire from the switch. There is another short black wire from this stud and the other end is attached to a brass connector on the plate. It looks as if the brass connector is isolated from the metal parts but it may be touching something behide the plate.

    Well, after 10 minutes the phot still hasn't uploaded so hopefully you've seen what I am describing. If not, I'll try to upload tomorrow.
  6. hdtvluvr

    hdtvluvr LawnSite Senior Member
    Messages: 512

    Here's another attempt.

    The white wire should be labeled wire from switch. The wire I'm not sure about is attached to the brass looking clip. While it is on a white plastic piece, the back side may be grounding. It was attached when I got the engine so I left it.


    Kill Switch.jpg
  7. pugs

    pugs LawnSite Gold Member
    Messages: 3,025

    The short wire kills the engine when you put the throttle all the way down.

    Where is the throttle when you are cranking? Move it up to high speed and see if you get spark.

    You should have it all the way up anyway as it looks like you have a combined throttle/choke...so if you want choke you will need to put it all the way up.
  8. hdtvluvr

    hdtvluvr LawnSite Senior Member
    Messages: 512

    I got everything back together and removed the short wire. I got the engine started. I've now realized that the throttle cable should come up from the bottom in order to operate the throttle properly. This was the mounting position for the old engine.

    The throttle cable is too short to reach from the bottom. I'm guessing that it is about 16 inches long. It looks like I will need one about 24 inches to go down through the firewall and then turn up to mount 180 degrees from the current position. Where can I get a new cable?

    BTW, thanks again for everyone's assistance!
  9. topsites

    topsites LawnSite Fanatic
    Messages: 21,652

    I've had this problem before with the throttle cable, the easy way out for me was to just get used to having reversed throttle connections. So now choke is off, and off is choke, somewhere in there is WOT and idle.

    We did eventually (the shop mechanic did) install a new plate with the proper markings, but once I got used to it being backwards I didn't really need it.
  10. hdtvluvr

    hdtvluvr LawnSite Senior Member
    Messages: 512

    Well, I go everything working properly. This new engine does a great job - should have replaced the old one long ago. The old one was the original and the mower was manufactured in 1982.

    Thanks for everyone's help.

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