25 hp Mercury Outboard "no spark"?

Question

I have a 96 model 25 hp Mercury 2 stroke. It stoped running 2 weeks ago on the river. I have tested the spark plugs/ coils and are not getting any fire. We have replaced coils with new ones and it was sugested that the ignition box/ switch box was bad.. 250.00 later and a new box. We are still haveing the same result. No spark.... I have checked the safety switchs and they are both working, open in normal condition and when they are activated they read a short on the DMM. I'm not sure what any of the other wires on the Switch Box should read. Any suggestions or any place I may beable to find troubleshooting tips. I do not have a manual and would love to have this thing back in the water before one would get here if I ordered it right now.... Thanks for any help.

Answer 1

This is the reason outboard owners shoud not attempt to repair their own motors. Any experienced, certified marine mechanic will tell you that when there is an ignition problem, the last component you should suspect are the coils. They RARELY go bad. The proper procedure is to work from the top down, starting with stator output. From there you check the output from the switch box which goes to the coils.



If the stator is putting out the proper voltage, then it is good. If not it is bad and needs replaced. But if a stator goes bad it can knock out a switch box too. So once the stator is replaced output from the switch box needs checked.



If the stator is good then you need to check the output from the switch box. If the voltage output is correct, then the switch box is good. But 99% of the time when there is an ignition problem and the stator is good, you will find that the switch box is not putting out the proper voltage spec.



If the switch box tests good, that only leaves one component, the coils. If everything to the coils tests within specs then the coils need replaced.



But like I said, it is very rare for a coil to go bad, let alone more than one at a time.



Take it to a dealer.

Answer 2

take the carb off the motor, hold it upside down and blow into the gas inlet (might want to drain the bowl first -- premix is an aquired taste, don't ask me how I know). No air should pass -- it should be airtight. If it isn't, then you've left out a gasket or an o-ring, or the float valve isn't seating properly. Every fastener should have either an o-ring or a gasket. The float valve seat should also have an o-ring. Did you replace both the float valve needle *and* seat? If you replaced one but not the other, it won't hold. The seat looks fine, but it's not. Did you remove any of the core plugs and forget to replace 'em? (those little lead contact lense-looking things). Your carb might also have some holes left by the manufacturing process that are filled with lead shot, which might have fell out, but that is so unlikely. About the same probability as a tornado blowing through a junkyard and spontaneously assembling a fully functional Boeing 747. If you hold the carb rightside up and blow through the gas inlet, should be very little resistance.

Answer 3

my 25 hp outboard starts, e des and will not start again. Getting gas but then no spark. any ideas

Answer 4

Wayne,do you have electric start?

You can contact me if you wish through this site and I will try to help if possible.

35 years as a marine tec.

Answer 5

stator