Merc 900 90hp question

[budman007]

I just obtained a 1978 Merc 900 90hp motor mounted on a old boat and I want to test it. Ok, first this is my first boat to ever touch. I know your supposed to have them in water or water devices before running. I wanted to see if the battery was good, so I charged it, installed it and turned the key...well it makes a noise from the motor, but nothing spins or anything(the noise sounds like the flywheel from an old mopar car or engine that the starter is going out of) Is this normal? Does it have to be in water to kick the prop? Does the motor have to be in the lowered position? does something else have to be moved or on for me to know if the motor is even good? I am just looking to really resell it, but need to know what is good and what is not. The boat needs some work, but its not THAT bad....almost new trailer its on. The boat is a 1979 19foot VIP B Ski boat. Thanks to all

 

[Chris1956]

Re: Merc 900 90hp question

Bud, You will want to use a water hose and flusher device to run that motor. The flusher will mount over the eight holes between the gearcase (bullet shape) and the antiventilation plate on the lower part of the motor. Keep the motor upright for test running. Also, mix 1 pint of TCW-III 2 cycle oil with six gallons of regular gasoline. This is a 50::1 fuel mix, which is correct for that motor.

Remove the front cowl by twisting the black plastic knob. Now remove the wrap cowl by unfastening the three metal toggle clamps. Take off the top cowl by flipping the black lever in the front of the top cowl. The starter is on the left of the motor. Now have someone turn the key and see if the starter spins. Post back with any questions.

 

[budman007]

Re: Merc 900 90hp question

Thanks for the info....Does the muffs have to be on before it will even kick over though in an attempt to start? I will try tonight to get into it and look at the starter. I took the side cover off the other day and just looked around....wasnt sure what I was looking for though....

 

[mthieme]

Re: Merc 900 90hp question

The muffs connect to the garden hose so as to provide water to the motor and keep it from overheating. Once running, you should see a stream of water coming out the backside of the motor. The exit hole is colloquially referred to as the pisser due the similarity (of the stream) of a certain male anatomical part (depending on how much beer you had the night before).

The flywheel is the big round thing on top of the motor with teeth around the circumference. The starter is mounted vertically on one side towards the front. It will have a heavy red wire 1/4"-3/8" diameter going to the bottom of it. The starter is cyndrilical slightly larger than a beer can.

(Where would we be w/o beer?)

I would try another (known good) battery before delving inside the motor.
Do not hot shot an outboard battery. You will blow the rectifier which is part of the charging system.

 

[budman007]

Re: Merc 900 90hp question

I did hook up a "battery jumper" to the battery itself and turn it on to attempt to make sure I had enough juice to start it. That shouldnt blow anything should it? Its not like hooking it to the truck or by-passing the battery and touching the starter with some jumper cables....or is it?

 

[Chris1956]

Re: Merc 900 90hp question

Jumper cables on the boat battery should be fine. Make sure it is plus to plus and negative to negative, or you will likely have a fire.

 

[budman007]

Re: Merc 900 90hp question

Ok, jumpered it to my car battery and hooked up the muffs and turned the key....it TRIED to start!!! WOO...ok next question. First, after getting a new battery....I did put some fuel in it(mixed to specs) with some stablizer...on the choke....when I press it, it clicks, do I need to hold it in when turning the key or just press it and let go? choke it everytime until it starts? Sometimes the prop turned faster then others....(I am guessing because of the bad battery) Next, there is a small pump maybe that connects to the fuel line, am I supposes to squeeze that or ???? Anyway to force a little go go juice into the carbs easily? I have the motor still proped up on its little metal arm, is that a problem? Thanks to all!!!

 

[Chris1956]

Re: Merc 900 90hp question

Attach the flush device. Turn on the water 3/4 of the way. Pump up the fuel primer bulb until it is firm. Lift up the cold start lever on the MerControl. Hold down the choke button and crank the motor until it starts, then release. Adjust the idle speed with the cold start lever until the motor warms up, and then push the lever down. If all is as it should be, the motor will run at about 1000 RPM on the flush device at idle.

I do not know what you mean by propped up on it's little metal arm!

 

[budman007]

Re: Merc 900 90hp question

Thanks for the reply Chris....I am guessing I can go to a marine store to find a Flush device? Where is the Cold Start lever? The little metal arm is this odd device that attaches by cotter pin on the very bottom of the boat and it raises up to the bullet part of the motor with a U shape that snugly holds the motor partially upright....yea I know it has a name, just not sure what it is called. At first the bulb feels kinda tight, when I pressed it a few times it got easier and I can hear air or fuel passing thru something.....Thanks again!!!

 

[Chris1956]

Re: Merc 900 90hp question

OK, I am not familar with the "little metal arm". It sounds like some aftermarket thing, for shallow water use or trailoring. The motor should be vertical for running it.

The cold start lever is next to the throttle lever on the MerControl. Flush devices are usually avail at marine stores and even Walmart stores. They are $3-$7 or so.

 

[budman007]

Re: Merc 900 90hp question

Hey Chris, can you email me at dbrown@zila.com. I will send you some pics tomorrow of the metal thingy and have another question still about the cold lever....the only thing on the merccontrol is 2 buttons, one black (I think) lowers the motor, the red one don't do anything(I figure it was to raise the motor, but not certain) then there is a choke button and trailer button, of course the lever with the 2 buttons goes F or R......unless I am missing something....

 

[rtpassini]

Re: Merc 900 90hp question

chris is the man when it comes to older mercs.

 

[budman007]

Re: Merc 900 90hp question

I totally agree 1000% on that statement....Chris is DA MERC MAN!!!!! DOO DOO DOO DOO MERC MAN!!!!

 

[Chris1956]

Re: Merc 900 90hp question

Budman, I sent you a PM.

it sounds like you have a newer MerControl. Perhaps there is a throttle only button on the throttle arm pivot, and no cold start lever. Usually you can push in the button and move the throttle forward, w/o it going into gear.