1985 Johnson 150

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maverick974

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I just bought a boat with a 1985 Johnson 150 on it. I'm just curious if some of you folks have an opinion on these motors? Are they reliable? Are they fairly economical for their size?
It's a 1985 Astro Glass fish and ski. 17 1/2 footer. It came with 2 stainless steel props. One is a 14.1/4 X 17 and the other is a 14 1/2 X 24. I won't be taking it on the water until next week. Which prop do you think would work best?

Thanks for your help.
 
jerryjerry05

jerryjerry05

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Re: 1985 Johnson 150

A 1985 anything won't be great on gas.
As long as you don't run it full throttle it shouldn't be too bad.
The newer they are the better the gas.
The 17 will be good to start.24 is probably best for a spare or for racing.
You have a tach?You will need one to check performance.
Put on the 17 go for a ride:1-2 people 1/2 tank of fuel(built-in tank?) Cooler.maybe a dog or a kid.
Run wide open throttle.RPM's should be about 5300-5500
Post your results in the prop section.
 
SparkieBoat

SparkieBoat

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Re: 1985 Johnson 150

I prop mine to hit around 5800 RPM. I guess you will end up with a 19 or a 21, the 24 sounds a little steep. They are great motors. The fuel efficiency is not as good as the newer EFI outboards but it is not that much difference. I have run carbbed, EFI, EFI 4-stroke and they all burn gas pretty good. It really depends on how you use a motor. The newer motors do not come anywhere close to saving you enough fuel to pay for the difference and the parts are stupid high, average electronic part for your 150 is about $200, EFI motors start at about $700 and go up..way way up. plus you will have great difficulty maintaining them your self, a carbbed motor is very easy to maintain and much cheaper. I have my F115 yammy for sale now..going back to carbs, EFI stinks bad. so you made a good choice so long as the motor is in good shape. Take care of it and it could last you a very long time.
 
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maverick974

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Re: 1985 Johnson 150

Hey, thanks for the info SparkieBoat. I bought this on a whim so I just wanted some reassurance that I didn't screw up and get an undependable engine. It looks great. Not a spot of oil under the cover and it sounds perfect but I've only run it on muffs so I can't rev it up until I get on the water.
I'm an avid bass fisherman and my last boat was an old Bayliner Trophy bass boat with an 85 hp engine. Even though it's just a Bayliner and the engine was just a Force, that was an awesome boat and it did the job very well and it did it very efficiently. I'm only hoping that the Johnson 150 won't break the bank when it comes to fuel. I can't wait to get it on the water. It's supposed to be in the mid 70's this week here in Arizona so I'll be on the lake tomorrow or Monday. Woohoo!
Anyway, thanks for your input. I really appreciate it.
 
SparkieBoat

SparkieBoat

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Re: 1985 Johnson 150

I would do a compression check on the engine. It should run out very strong on that boat. Keep your RPMs under 6K, with that 17 prop it may want to go higher. the 24 prop is probably too big. a 21 would probably be about right..maybe a 19. keep it at around 3/4 throttle for best MPG. make sure you trim it up some after you get on a plane, you will feel it speed up some when you hit the right spot.
 
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maverick974

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Re: 1985 Johnson 150

I'll do the compression check. I should have done that already.
6 k RPMs. Isn't that a little high? I've been looking on here and from what I can find, it says about 5500 rpms is tops but I'll keep an eye on the rpms, specially with the 17p on it.
Thanks for the tip on 3/4 throttle. I need to save all the fuel I can. When the weather is good, I'm on the lake a LOT.
If there is anything else you can recommend, please let me know.

Thanks again
 
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emdsapmgr

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Re: 1985 Johnson 150

You shouldn't have any overrevving issues. Likely that engine may have rev-liminting dual power packs on it. They won't let the engine rev past 5800. You can check the printing on the side of the pack. That low port engine powerhead runs out of crankcase breathing capability around that rpm anyway. Check the 150 model number on the serial plate-they made two versions that year. OMC made the normal 150 hp model, termed a J150T, and the high performance 165 hp model which was termed a J150S.
 
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maverick974

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Re: 1985 Johnson 150

emdsapmgr said:
You shouldn't have any overrevving issues. Likely that engine may have rev-liminting dual power packs on it. They won't let the engine rev past 5800. You can check the printing on the side of the pack. That low port engine powerhead runs out of crankcase breathing capability around that rpm anyway. Check the 150 model number on the serial plate-they made two versions that year. OMC made the normal 150 hp model, termed a J150T, and the high performance 165 hp model which was termed a J150S.
Click to expand...

Well, I took it out a couple of days ago and I was hugely impressed. The hole shot was incredible.
Anyway, other than a minor problem with the tach and an alarm going off for a few seconds, I'm very happy with it.
It is the J150T model but it has plenty of power for me.
When I took it out, the 17P prop was on it and I was extremely happy with the performance of that. I'm going to try the 24P but I'm guessing I'll keep the 17P on it. Awesome hole shot and it's plenty fast for me.
 
SparkieBoat

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Re: 1985 Johnson 150

you need to fix your tach problem..and figure out why the alarm...
 
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emdsapmgr

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Re: 1985 Johnson 150

Your engine is the basic 150 hp model. Sparkie's right. A tach problem is a possible symptom of a non-functioning battery charging system. When the rectifier/regulator goes, the tach quits functioning and the charging system quits recharging the battery. You need to keep track of the battery voltage to see if it's actually a defective tach or a bad rectifier/regulator. Once you get the tach working, you can see what rpm's the engine is running. The 17 pitch prop is a fairly low pitch and will give really strong low end performance. Possible that you may find that a 19 pitch may also perform well, but with added top end speed. You can have fun testing out various props on your new boat.
 
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maverick974

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Re: 1985 Johnson 150

I've checked the wiring to the tach and it looks like everything is ok. How would I check to see if the charging system is working?
I believe the alarm was an over-heat alarm caused from a sticky T-stat. I'm going to replace both T-stats before I go out next.
 
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emdsapmgr

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Re: 1985 Johnson 150

You'll need to measure the voltage across the two battery posts. Normal battery voltage is approximately 12.6 volts. When you start the engine, it may read slightly lower. After running the engine for 15 minutes, the battery should recharge to that 12.6 volt figure, then slightly increase to around 13 or 13.5 volts as you continue to run it. That indicates the charging system is working normally. If the battery voltage goes down from 12.6 volts and continues to decrease over time, the charging system may not be working properly. If you find the charging system is not working and you effect the proper repairs, it is very possible the tach may start working.
 
SparkieBoat

SparkieBoat

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Re: 1985 Johnson 150

emd is correct..but the best way to check your regulator is to get a dva adapter like the one in my sig below..just go ahead and get it..$25 and you will never be sorry you got it. the other link goes to a free troubleshooting guide.
 
M

maverick974

Petty Officer 2nd Class
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Messages
122
Re: 1985 Johnson 150

emdsapmgr said:
You'll need to measure the voltage across the two battery posts. Normal battery voltage is approximately 12.6 volts. When you start the engine, it may read slightly lower. After running the engine for 15 minutes, the battery should recharge to that 12.6 volt figure, then slightly increase to around 13 or 13.5 volts as you continue to run it. That indicates the charging system is working normally. If the battery voltage goes down from 12.6 volts and continues to decrease over time, the charging system may not be working properly. If you find the charging system is not working and you effect the proper repairs, it is very possible the tach may start working.
Click to expand...

SparkieBoat said:
emd is correct..but the best way to check your regulator is to get a dva adapter like the one in my sig below..just go ahead and get it..$25 and you will never be sorry you got it. the other link goes to a free troubleshooting guide.
Click to expand...

Thanks for the tips on checking the charging system. I'll order the DVA adaptor. The lakes around here are fairly large and I certainly wouldn't enjoy getting stuck on the wrong side of a 25 mile lake.
I'll let you know what I come up with.

Thanks again
 
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