Could be the neutral safety switch I had that problem on and off starting and it was a short on the neutral safety switch

 

Your not useless now do you just replace switch

 

Yes. Mine was like ,80.00 at the dealer.ouch.so I would check it first.

 

Is it a VRO? Or what year might be a big help too.

 

2003 Johnson 90

 

Can you hear the choke click? Is it only when it is a cold start, or any time?

 

Can hear choke mech say it working it just that thier no time or reason start right up sometime then it won’t put in water start right up then fish for15 min then won’t

 

had one like yours ,to the shop ,an another shop ,and another , finnally fixed it, traded it on a 115 merc opti. it starts every time.

 

When it won't start, has anyone diagnosed whether it's getting any spark or not?

 

I have one like yours that is a couple of years older. 88 SPL. Same motor without the VRO. It has been cold blooded since it was new. It always starts, but the first time of the day I may have to crank it a bit and push the choke a bunch of times. After it has warmed up its much better. There's a fine line between priming it enough and flooding it. Wonder if yours is getting air at the fuel connection at times? Might be an O ring?

 

Two different mechanics went over it said it was good what strange is when it hardtop start could be cold or hot out crank in it then just takes off I seem to think it kill switch

 

If it's electrical...or ignition switch...or bad electrical connection in the ignition circuit somewhere from the key back.

Without diagnosing whether it's electrical or fuel when the problem arises, it's a guess at best to try and figure it out. If it wasn't acting up when your mechanics looked at it, that's most likely why they can't tell you what's wrong with it. Sporatic issues like that can be really hard to diagnose.
You can get an inline spark tester that plugs onto a plug then the plug wire attaches to the other end of the tester, take it out and run it until it acts up. When it won't start, look and see if there's spark going through the tester when the engine is being turned over.
I think if it were me, I would start at the ignition switch checking all electrical connection from the switch back to the engine.

 

Not sure how old your motor is, but I had a very similar prob. with my merc 50. after 4 different attempts to fix. had the carbs rebuilt 3 years ago and have not had the problem since. merc is 1996 something about todays gas messing up internal workings.
good luck
EB

 

#14 is the the way to progress through the problem, otherwise you are throwing random darts.

 

Fast water I think that’s plan

 

its the ETHANOL I tell ya! I blame it for everything Russell, just couldnt resist

 

That I agree the government wanted ethanol now I can’t start my boat honestly why they want it don’t remember was it to save the fish

 

it was to create new companies ,to fix all the problems the darn stuff would ruin.

 

check the fuel supply to the choke, I have found that motors need a lot of fuel to start well. and if its start then not start maybe ignition circuits, stator , bad wire , power paks… and clean carbs are a must …maybe on one of those times it gives ya a hard time starting drop it in N press the release for neutral and throttle and add fuel while cranking .

 

If the kill switch is on does the motor still turn over I knowsounds dumb but not sure if mine is working so just wondering

 

Yes...if kill switch is triggered or bad the engine will still turn over.
The kill switch kills the spark to the spark plugs. Not power to the starter.

 

get you a squirt bottle and fill about half way full of premixed gas. when the motor wont start squirt some gas in the carbs and try again. this will tell you if its a gas problem. you can do another test on the ignition switch when it wont start by taking a 12v tester then find the hot wire coming in to the switch. turn the switch to the run position and check to see if you have a hot/run wire coming off the switch.
sherman

 

Thanx guys much appreciated

 

I have an old 115 hp merc that wont start at times when its cold. AT TIMES if it sets for 10 minutes or longer it wont start and I have to use the squirt bottle and prime it. the squirt bottle works, just squirt some gas in the carbs and she fires right up. starting fluid works but has no lube in it. i've had the carbs rebuilt, all new gas lines even on the motor, new tanks and it still does this. runs once its started. I would think if it was anything but the ignition switch or a gas problem it would die running down the lake.
sherman

 

Sherman, Those older inline 6 cylinder Merc's are notoriously cold blooded. Almost all of them only had choke shutters on only the bottom two carbs. The throat of the upper carb which feeds cylinders # 1 & 2 has no choke provision. On the last couple of model years (guessing 85-86ish w/o looking) Mercury switched them to a primer which feeds all 6 cylinders. I have a customer with a 1986 Mariner equipped with the primer. Some of the older remote controls wouldn't advance the throttle/spark very much either which compounds the problem. Mike

 

yep old mercs are cold natured, i have an 86 90hp merc but it has a solenoid that feeds from the top carb bowel into the intake with 3 hoses one feeds each intake, it will flood easy if you get antsy . mine turn key on , set throttle in neutral and move forward to add fuel, just past detent, push key in for 10 sec and zoom starts up ...takes awhile to warm up though