merc 90

[bobbymatthews]

I am having trouble starting my mercury 90 engine. I has 6 spark plugs and is a 2 stroke. Does that mean it is a six cylinder. I only see 3 carbs. It has a front fuel tank and a button that clicks when it is pulled out and I am presuming this is a fuel pump or something. I have gotten it going about 4 times and it runs great but it does not start right up without a lot of cranking. Am I flooding the engine? Once I get it going I do turn off the button that pumps(or clicks). It does have a choke by pushing in the key.
Am I just doing something wrong?? Also when I got the boat a month a go I noticed that the 3 and 4 plug wires seemed switched and so I switced them back to match the numbered electrical wires as the other wires matched number for number. It runs super well. The plugs and wires were new and the carbs looked really clean. I run 32:1 ratio of gas to oil. Is that right?
The boat is a 21 foot 83 Force ski boat. I am not sure the date of the engine.

Any assistance is appreciated!!
Thanks bobbymatthews

 

[Chris1956]

Re: merc 90

Bob, A serial number will tell us the year. It is likely a inline six 2 cycle Merc. Very popular engine made from the sixties to the late 80s.

Mix the fuel at a 50::1 ratio (6gal gas to 1 pint TCW-III oil)

Never run the motor out of the water unless you have a flusher installed and water running to it.

To cold start the motor, pump the fuel primer bulb until firm. Put the cold start lever on the control all the way up. If you do not have one, see if you have a throttle only button, and advance the throttle an inch or two. Push to choke and hold choke while cranking, until engine starts.

 

[bobbymatthews]

Re: merc 90

I do not have a bulb but a fuel primer motor I believe. That is the clicking sound I hear when I pull the knob back. I will check if I have a cold start lever
but I think I only have a throttle lever. Throttle only button?? There is throttle button at the axis of my lever. Shouls I push it or what?
Where would the cold start button be on the controls or on the engine?
Thanks for anwering. I tried starting it today but fuel seems to leak on the water and my battery ran down again. I am recharging it.

 

[milehighboater]

Re: merc 90

yep, on the throttle/gear shifter handle there is a button in the center that when pressed in if you put it in gear it will only operate the trottle and keep the engine in neutral, so you can rev up the engine without having the prop spin. I have a 75hp merc with the choke on the key, When I'm starting I'll press it in when turning it over and it usually starts within a couple of tries. good luck.
P.S. when you are starting/throttling up make sure you don't over rev the engine 5000-5250rpm is redline. I hold mine at start-up at about 2000-2500 rpm for about 30 sec and it does the trick.

 

[bobbymatthews]

Re: merc 90

Thanks to all who answered, I did get it started using the throttle button and pushing the lever forward. It still took a few cranks, but maybe I will get better at it. It ran great. Now another dumb question is a merc 90 mean it is 90 horsepower? it is a straight six. Isn't that a pretty big motor for a 21foot runabout?

Has anyone else had an electric fuel primer? it is a button on the console that pulls out like the two light switches. It starts clicking not humming like the electric sump pump. There was a piece of masking tape next to it that said "pull before starting",but how long should I let it run before cranking or should I crank right away? I have pushed it in when engine starts without a problem. I think I am flooding it somehow.

I bought the boat last month so I am a first time owner however I am very hany with car mechanics.

Thanks to all.

bob