1998 40 hp Tohatsu Idles find go to put in gear it backfires then dies

[boat24]

Since I am not a wealthy man and a life long do it your selfer. I have a prolbem, been on this site for years but this is my first post. I am amaze how the people out there have helped so many other people.
My engine usally has great pep. Three weeks ago I was out and it did what I said in my title. The flywhell also seem to freeze up but I would wait a few minutes try to start again same thing would happen. I brought it home removed the lower unit
(you'll love this) I found a metal piece down in the hole where the shifter rod goes into. Its about size of a 2/5. inch bullet just sitting there and very rusty, I went over the parts book but could find nothing to resemble it. I hoping thats the prolbem. I also check all fuel lines, soaked the pistons overnight with rust inhibtor, the fly wheel seems fine. Did a plug test, good spark. Inspected all connections. Oh yes I do have a manual. Going to try it this weekend. Any help anyone can give will be very taken and appriciated. Thank You

 

[TOHATSU GURU]

Re: 1998 40 hp Tohatsu Idles find go to put in gear it backfires then dies

Backfires can only occur due to a broken flywheel key or a bad trigger coil or CD module. Check the flywheel key by pulling the flywheel. Check the ignition parts using the specs and test procedures outlined in your service manual.

 

[boat24]

Re: 1998 40 hp Tohatsu Idles find go to put in gear it backfires then dies

Backfires can only occur due to a broken flywheel key or a bad trigger coil or CD module. Check the flywheel key by pulling the flywheel. Check the ignition parts using the specs and test procedures outlined in your service manual.

Thank You for the fast response. I have followed your answers helping people for quite some time.
Have to go buy wheel puller on wed. will get back to you. I also did not mention that there was a big chunk of my spark plug cap missing, no idea how that happened.

 

[boat24]

Re: 1998 40 hp Tohatsu Idles find go to put in gear it backfires then dies

I checked in my parts book and manual they do not mention a "flywheel key"

 

[pvanv]

Re: 1998 40 hp Tohatsu Idles find go to put in gear it backfires then dies

I checked in my parts book and manual they do not mention a "flywheel key"

It's probably called a "magneto key" in your book.

What Elvin was describing is that it's possible to shear that woodruff key, which allows the motor to fire out of time. Some customers may also call a pop in the carb a "backfire". That pop can occur if you are too lean. Regardless, get the ignition in top shape, replacing plug cap, etc., as needed (and checking that woodruff key), and testing the CD and coil, and go from there. When reattaching the flywheel, the tapers of both the flywheel and shaft must be bone dry, with no contaminants. You can wipe them down with lacquer thinner or acetone, etc.

Also, you must not use a "claw" style puller to remove the flywheel, as you can warp or crack it. Be sure that you use a "harmonic balancer or steering wheel" type of puller, that uses bolts into the flywheel.