1988 90 HP Mercury Outboard - Won't Start

[imported_dgordon]

Hi, firstly I’d like to say that I am a first time boat owner and additionally new to iboats.com. So please bear with me because I know nothing at all about boats yet. I have been reading some postings and see that more info the better so here we go...

I just bought a used 19 ft fiberglass boat with a 1988 90 HP 3 cyl 2 Cycle Outboard motor (Model No. OB241539). (Don't worry I bought it for practically pennies.) I wasn't able to get it started but it did does seem to turn over. I did compression tests and found that the first cylinder has about 20 psi lest than the second and third cylinders (which had the same psi). I also established that the battery is full and I am getting spark on all three.

So I am assuming that there must be a fuel problem. I know that 2 cycle engines usually have to have a mixture of gas and oil, but I noticed that this engine has a 1 gal. oil tank on its side (which is full BTW). SO firstly, does this mean that I don’t need to premix and that the engine mixes it? Which leads me to my second question which is that I also figure the gas in the tank may be old and I began to siphoning out the tank and noticed it was just about black. I don't know if gas turns this color or the previous owner premixed. If he did however, and he wasn’t supposed to, would the extra oil prevent it starting? And if so, how do I flush/clean out the engine? Or what parts would need cleaning/flushing?

Also, someone mentioned to me that there might be a safety sensor somewhere on the motor that might be not allowing it to start. Is/Are there such sensors on the motor? If so, how do I eliminate the interference?

Any help is greatly appreciated.

David

 

[crunch]

Re: 1988 90 HP Mercury Outboard - Won't Start

K... so how long since its run? By all meams get rid of the old gas, if the engine hasn't been run for a long time, mix 50:1 even if it has oil injection and run a few gallons thru it (lubes things up)...

Spark?... do you have a manual? Don't get a Seloc manual, I've found that they expect you to be an expert on things that matter, and an idiot on things that don't.

 

[Silvertip]

Re: 1988 90 HP Mercury Outboard - Won't Start

Black gas is not a good thing -- especially if you have no idea how long its been in the tank or whether its been treated before lay up. Drain it and add a 50:1 mix with fresh gas. This is so you can run it safely and ensure the oil injection is working. With the engine vertical, place a mark on the tank at the oil level. This will allow you to verify oil is being used. If the injection system is working, you can quit pre-mixing. As mentioned, check for spark. If none, make sure the safety lanyard has not been activated tripping the little switch just beneath the ignition key. If it has, push the switch back up and try it. Starting procedure is 1)squeeze primer bulb until firm, 2) raise fast idle lever on control box, 3) push in on key to choke while turning the key to start. When engine starts, lower fast idle level and be ready to push the key in momentarily a time or two if the engine begins to die. When running smoothly, drop fast idle lever fully. I suspect this unit has been stored for some time so a water pump impeller change and carb cleaning, and thermostat change are suggested. DO NOT run the engine without a source of cooling water.

 

[andy6374]

Re: 1988 90 HP Mercury Outboard - Won't Start

Do exactly what Silvertip recommended and do a decarb once you get the engine running. I betcha you'll close the gap on compression numbers between the 3 cylinders.

 

[imported_dgordon]

Re: 1988 90 HP Mercury Outboard - Won't Start

Well firstly, thank you to all that answered.

To answer custombycrunch's initial question of how old the gas is, or how long the engine hasn't been run; The story is that I purchased it from someone who bought it from a dock, whom sold it (with permission BTW) to collect the money that the first owner owed them for their storage and dock fees. And as-far-as I know the boat was never run after it was purchased from the dock, and that owner had it about 5 months, and g-d knows how long the dock had it. So to answer the question of the gas age- Its plausible to assume the owner whom I bought it from whom puchased it from the dock flushed the fuel tank and refueled it about 5 months ago when he purchased it. And as for when it was last run; I'd think it would be safe to assume about a year (figuring its been a season since the original owner last used it).

Now as for the starting procedure, I did try to start it again using Silvertip's tips, but I coudn't even get the engine to cough. I bypassed the fuel tank to a 4 gal gas can full of fresh fuel and oil (50:1) but still no luck. So than I sprayed a mist of the 50:1 fuel directly into the 3 carbs and not so much as a pop, cough, or wimper (well maybe from me :'( ). I did check on the spark plugs and they were sparking. What I did however notice was that the plugs, although new, were each coated in a nice amount of oil. It seemed a bit much oil considering the ratio of oil to gas. COULD THE OIL BE SMUTHERING THE ABILITY OF THE FUEL MIX TO IGNITE? What can I do to try and flush out the cyliners (if needed)?

Oh yea, I did also check on that safety switch under the ignition key and because all the writing was worn off, I tried to start the engine in both positions. But that didn't do it either.

Fire, Fuel, Compression: Right? Is there something I'm missing. HELP PLEASE!!

 

[imported_dgordon]

Re: 1988 90 HP Mercury Outboard - Won't Start

Oh yea, one more thing.

I noticed after every time I tried to start it, there was oil running out what I believe is an exaust hole located on the lower unit a little above the prop. It did seem to be just oil and not the 50:1 mix.
-Is this indicitive of something?????

 

[imported_dgordon]

Re: 1988 90 HP Mercury Outboard - Won't Start

Should I be trying to start it with the muffs on? Would that stop it from starting? Or are they only neccessary to cool the engine when running?