Johnson 150 running issues
 

Today i went to run my 1985 Johnson 150 on a 6 gallon tank with fresh gas and it wouldn't run below 1000rpm. If i turn the choke knob it will run rough below 1000 rpm. When i hold the carbs open a little it will crank and run beautiful. I try to run this motor once a month on fresh gas with stabil in a small tank but its been three months since i have run it. Tomorrow i plan to check plugs. What else should i check? I am beginning to think its a carb issue. I do not know when they were cleaned last. Right now i have adjusted the throttle cable out so it runs good. But i hate to cover up a problem by doing so. Anybody got any suggestions?

Also i have a 25" shaft Yamaha 150 2 stroke i may put on but need a remote control.

Pull the carbs and clean out the jets inside of it.

Would i need a chilton book for that? I haven't pulled the silencer cover off yet so i don't know what i am getting into. I cleaned/rebuilt all the carbs on the twin 150 Yamahas on the big boat. Is it pretty much straight forward like the yammies, where i can see the jets when i remove the silencer? Also would i need a rebuild kit with all the gaskets and such?

The jets that need to be cleaned will be inside the float bowls. If your careful you can normally re-use teh gaskets, but it is always a good idea to change them.

I just looked up a parts diagram for the carbs. The jets i am cleaning are #5 correct?

One thing I've found through the years is to always run any gas going into my engines through a fuel filter....even from a portable gas tank. I made up a portable fuel line that goes into a filter, and then the filter has the regular engine fittiing on the outflow side. I figure that a little protection is well worth the slight extra cost of the filter.

Good thinking, but i already have that covered. I hook my portable tank to the inlet of my Racor fuel filter. My main tank hasn't been hooked up since August!

#5 and #15 need to be cleaned inside as well as checking teh ports that go from #5 down to the bottom of the float bowl. And check #3 while you have it apart to make sure they are clean.

I took the top carb off this morning and was amazed at what i found. Both #15 was clogged with a thick green crap. The bowl has a puke greensih film in the botom and in the passages #5 to #15. How can i clean this plastic bowl without harming it. O'reillys had nothing that would work. After seeing this i am surprised the engine ran at all. I figured i would blow everything out with compressed air. So far i have #5 #3 #15 jets from the top carb soaking in cleaner.

Below is a picture of the bowl.

They should be metal on an 85 150 as that is the old style cross flow engine. As for cleaners, I use EVINRUDE engine tuner in teh gallon jug to soak them. I also have an ultrasonic cleaner that I use if they aren't that bad.

These are black plastic bowls. i have been soaking the jets in a carb cleaner i got from o reillys in a one gallon can. While i have them apart, what is the float drop measurement?

Below is a clean jet next to a dirty one.

So whats the best way to clean plastic carb bowls? :head:

You can soak them in SEAFOAM for about 20 minutes and see how much comes off. DO NOT use carb dip as it will eat the plastic. I personally use EVINRUDE engine tuner in the ultrasonic dip tank.

i've always used a 50 / 50 mix of mineral spirits and lacquer thinner. i use that on the whole carb assembly including the plastic parts too. then blow it all clean with the air compressor.

WD-40 seems to work good on plastic too.

There is a marine program at George Stone where i am taking welding. I am going to let them do carb kits on all the carbs and clean the bowls so hopefully there will be no more issues. After they do carb kits, they will put my outboard on the dyno and see what it puts out.

Did you ever read Tom Sawyer? :hide:

Update
 

Found out i had low voltage on two plug wires, had carbs cleaned, a few electrical gremlins with the ignition, and the shaft mounts and steering shaft are shot. Motor had 92-94psi compression on all but one cylinder which had 82. If nothing else breaks when trying to repair it, it would cost over $1000 just for parts.

So i am having another motor installed this coming week, a 1986 Yamaha 150 25" shaft. I will build a jack plate, out of some 4x4 1/4" wall square steel tubing i have, so it will work on my 20" transom. Now i just need a remote control.

Jason I strongly suggest that you source some aluminum angle for your jackplate..... rust streaks are a real pain in debut.

X2 And if you go near salt water at all metal rusts SOOOO fast...:head:

This is just temporary to get me back on the water, I have found a hi-jacker fixed jack plate that lifts 5" and sets back 4" for $150. If everything works out i will purchase one. But i refuse to throw anymore money into this boat than i have to. Carb rebuild, new tilt/trim motor, and many many hours of tracking down problems with this motor and now this. I am done with it!

I will paint the steel jack plate with an epoxy paint after i get it welded up, to delay the rust for awhile. Like i said, once i get the Yammie on her and get confident again i will purchase an aluminum jack plate.

http://www.wholesalemarine.com/p/T-H..._JP_d_4FA_d_DP

In that case, I'd just throw it on and try her out.... having the engine 5" low will limit how much you can trim up for speed without porpoising but unless you need to run very shallow water it won't hurt a thing.

After a little thought i decided to go ahead and get the fixed jack plate. Got my square tubing cut to size and found out the tubing would have to be at an angle and then the transom side holes would not hit the tubing, if i had 4" tubing it would work. But i had 3". A little bit of a leap before i looked issue. :cen:

Maybe i can use it for a bow guide now for the trailer. :haha: