first question what is the man overboard switch?
2nd question where can I buy this manual?
so I have replaced all 4 spark plugs and all 4 gaps are set at 0.085mm.
I have used a multi meter to test all 4 coil connections so I know I do not have an open circuit In the wiring harness. My problem right now as it stands is I am NOT getting spark on 2 and 3 cylinder but I AM getting spark on 1 and 4 cylinder.
I know that the coil and the spark plug are good on cylinder 2 and 3 because I can swap either one and one over to 1 or 4 plug it in and get spark. I’ve tested the 3 wires on 2 and 3 cylinder all the way to the battery with good connection. So I am STUMPED on why the number 2 and 3 cylinder are not firing! I have NO check engine light coming on while I am cranking the engine.
The man overboard switch is where the safety lanyard that you connect to your PFD clips into a switch on the helm. If that clip is pulled, the switch drops down under spring tension, opens the ignition circuit and the engines shuts off and keeps the boat from motoring on after you fell out of the boat. Check this switch not only for connectivity, run an ohm check across this switch contacts when cold to see if you have high OHM readings.
Go here to find your shop manual, they are roughly $90.
YAMAHA MANUAL STORE
Are you sure that you gapped the plugs at .085mm (.003”) and not .85mm (.033”)? I dont know what your boat manual says, my manual shows spark plug gap at .028” to .032” which is .715mm to .815mm. Pretty sure the engine in your boat is different than the ones in mine. Judging by other posts on this site it sounds like the spark plugs are pretty important performance wise.
There is/are neutral safety switches in the throttle that keeps the engine from starting if any position except neutral is selected. On my boat the engines won’t even crank if the throttles are in a position other than neutral, your boat could be different in that the engines may be allowed to crank but the ignition will not fire the spark plugs. Just something else to eliminate.
OK so you have spark on cylinders one and four but not two and three when it’s cold correct? Have you repeated the test to check for spark after the engine is warmed up when you say that the motor starts right back up again? Perform that simple test to see if your results are the same. Just because you checked connectivity on the coil packs back to the battery doesn’t mean the coils themselves are in serviceable condition. Try using your multi meter to check the OHMs on the coils and verify that 1-4 have the same readings cold and hot. Again this test is what the manual will help you with. See attached photo.
In my experience with dirt bike stators/charging systems which are similar to these boat stators, the failure or problems with ignitions would occur when the stator got hot, and a broken wire inside the stator would lift, opening the coil and the engine would shut off. After letting the stator cool the bike would start back up again. In your case, it almost sounds as though the opposite is true, some component when cold is opening or almost opening a winding in coil some where. This is why you need to run OHM tests per the book to assure the electrical aspect of the ignition system is sound.
You need to run OHM tests and not just connectivity checks.
Have you unplugged all of the multi pin connectors and visually inspected them for corrosion and cleanliness? Remember your original spark plugs? (I’m still blown away by how badly those were corroded in what should be a sealed environment). Use a bright light and a magnifying glass to look down into the female sides of the pins and at the male pins. Use CRC Lectra-Motive contact cleaner to spray out the connections and use compressed air to blow them out till dry. Don’t just clean the connections, inspect them if possible first to see if you find a problem. Example: There is a couple I know of who have an Earth Roamer camper based on a F-550 chassis. They started to experience engine shut off / no start problems. After several dealers and a lot of parts an individual diesel tech they took it to knew exactly what it was. There is a large multi pin connector inside the truck under the dash. Several of the pins were corroded and black. This was caused by the fact the truck was now a camper and there had been excessive humidity inside the cab from the couple living in it in cold weather with the windows closed.
Once you have solved this problem, I highly recommend you go back through these connections and fill them with dielectric grease to keep the pins from corroding and to keep them free so you can pull the connectors apart if necessary. I’ve done this on my dirt bikes when they were new to keep any problems from occurring going forward.
Be careful with contact cleaners as they will cut the finish on plastic, meaning it will dull the finish.
Or at the end of the day you can take it to a reputable dealer who has a trained mechanic with all of the tools and let him trouble shoot and fix the problem and you will be done messing around with this problem and you will be out enjoying your great starting boat.
Hope all this helps!
