1991 40hp John. won't start

[darylf08]

I'm Lost!!! I have a 1991 40 Johnson that after 3 min of running @ full throttle, it dropped to 2800 RPM's. Swapped coils and did the same thing, just replaced the ignition modual ( Power Pack ) under the flywheel. Did not go with a OMC Mod. went with a Sierra Brand.. Removed the Plate Sleeve from the Retainer ring only. replaced the Modual with new one and now it will not start. I get spark from both plugs, Reversed plug wires, changed them back and shot starting fluid into each Cyl. and it does nothing, just cranks. Acts like no fuel but I figured the starting fluid would at least fire to prove it was a fuel issue. What can I check next, the boat ran perfect before this dropping RPM's. Any help would be greatly appreciated.
Daryl

 

[scrampbell]

Re: 1991 40hp John. won't start

Sounds to me that your original problem was/is gunked up carb jets. Did you take off the flywheel to replace a part? If so, it wasn't your powerpack.

Also, if you took off the fly wheel and now it's not starting but you get spark then it seems like you may need to verify that your timing is correct. If it's not sparking at the right time (near TopDeadCenter) you don't get the kind of ignition that will make the motor run.

Did you check your spark before replacing all these parts?

Best advice given on iboats is to get a shop manual for your motor. You can check with your local library if you're cheap like me.

 

[Rick.]

Re: 1991 40hp John. won't start

I have a new to me 95 40 hp. c/w VRO. I have been reading a bit about it and there is a built in motor protection sort of thing that will reduce your RPM's if you are overheating, running lean on oil, etc. So this could be your problem. Wish I knew more about it but I'm pretty ignorant at this point. Best of luck. Rick.

 

[Silvertip]

Re: 1991 40hp John. won't start

If you are getting spark but the engine does not start, I would look at the flywheel again. Did you get the "key" back in or was it partially or fully sheared. The flywheel can only go back one way with the key in place. If it was sheared you may not have noticed it and just stuck the flywheel back on so the engine is now out of tiime by a bunch.