1989 150hp merc outboard

[Kev144]

Hey guys, new to the forum but not new to boating. I am somewhat new to these bigger outboards as we always run I/O. My brother is about to buy a 1990 speed boat (not sure on boat brand) but the motor is a 89 150 merc. I was just wondering if any of you merc guru's can tell me everything you can about these motors from ups to the things to look out for!

Add: It has oil injection.


Thanks in advanced

Kevin

 

[j_martin]

Re: 1989 150hp merc outboard

I'd run a compression test on it. If it's 120 psi or more and within 10 lbs per cylinder, it's good. Run it then, and if it goes good, it probably is.

They come set up a little rich, and if the carbs are right, the reeds aren't bad, and the linkage and timing are set right, they go pretty good. It's 2.4L with about 160 hp at the prop right out of the box.

Unfortunately, there seems to be quite a few mechanic wannabees that don't pay attention to detail, and will misroute bleed lines, misadjust linkage because they think they know what they are doing without the book, and put in unsuitable parts. One that bit me on my 88 XR4 is the "authorized merc mechanic" put in a cheap plastic aftermarket bayonet connector to fix a fuel problem, and it added to the problem. The plastic connector just won't pass the 15GPH this engine wants at WOT. (the original problem was contaminated fuel plugging the filter.)

I put a little oil in the main tank (about 0.8 oz/gallon) so if the oil pump fails, the engine will live till the alarm goes off and I can slow down. That much oil will get you home at half throttle. I consider the oil injection system more reliable than my memory, but that ain't saying much. I think If my life depended on it, like big water boating, I would either pri-mix, or put on an aftermarket electric oil injection system.

The quickest way to kill this motor is to starve it for fuel, especially at WOT.

The funnest thing about this motor is having teenagers beg me to slow down.

hope it helps
John

 

[Kev144]

Re: 1989 150hp merc outboard

cool thanks for the info. We will most definatly check the compression. Its on a 17 foot speed boat (as i said not sure the make atm). I'm sure we should be a ble to get almost 60 out of this boat.

Also, the prop on it is dinged and i will be getting a new one for it. What would you guys suggest pitch wise and SS or alum.?

 

[MercFan]

Re: 1989 150hp merc outboard

Pitch has too many variables to take an accurate guess. It depends a lot on the weight of the boat and the hull shape. I'd just get what's on there now. some of the experts here could hazard a guess much better than mine, but I'd guess it probably has a 21" or higher on already. The thing to look out for is that you want to reach maximum or recommended rpm at full throttle, and that's dictated by your pitch.
Aluminium is cheaper and is generally better if you recon your prop is gonna get a ding or 2
Stainless steel is more expensive, but gives more performance because the blades are thinner and thus have higher efficiency.

For a first boat, I'd go for an aluminium honestly. 60mph is nothing in a car, but around 45mph in a boat is... Well... exilhirating would be a nice way to put it.

 

[j_martin]

Re: 1989 150hp merc outboard

I have an 88 XR4 150 on an 18' bass boat, fully rigged for fishing. It runs in the high 50's, even low 60's on a good day. (GPS) It's turning a 24 pitch high five at 5800 rpm, running factory fat. I use a 22 pitch for water skiing.

At WOT, it can be a handful if the water is a little rough. Liketa wrecked my pants a couple of times learning how to drive it.

hope it helps
John