1983 Johnson 150 one dry plug

Flats

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J150TXCTB. Ok here we go. Three 2 barrels all rebuilt. Entire fuel system replaced , no VRO. Ran it this afternoon and it gets to about 2000 rpms. Problem is that if you are standing behind the motor it is the top right cylinder is bone dry. All other cylinders are perfect. Any ideas ? Reed plates?
 

Joe Reeves

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Re: 1983 Johnson 150 one dry plug

Have you checked compression and spark on all cylinders?

Standing in back of and facing spark plugs, the top right (starboard) cylinder is #1 cylinder... left bank would be (port).

If you have compression and spark... if a reed plate was faulty, that would cause fuel to be pushed out the carburetor throat.

A more likely cause wound be that the high speed jet for that cylinder is fouled. Fuel must flow freely thru that jet before it can gain access to any other fuel passageway.
 

71Windsor

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Re: 1983 Johnson 150 one dry plug

double check your carb. i would also maybe try taking a spray bottle with 50:1 fuel/oil spray it through the top carb while running and check if your plug is wet then. that will give you a better idea whats going on.
 

Flats

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Re: 1983 Johnson 150 one dry plug

Yes it has good compression and very good spark. No gas coming out of the throat. Just had me wondering because the top left plug facing the motor does have has on it. But the right one is dry. And that is with a new plug. So I will try squirting some pre mix into the venturies and see what happens. I guess If it gets wet ill rebuild it and clean it again.
 

Flats

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Re: 1983 Johnson 150 one dry plug

Also after trying to run it in the water , when first pulled the new plugs , the bottom two plugs looked perfect and the top left looked perfect but middle two were REALLY FOULED. Like bad! I thought this would be caused from no fuel going to the top right plug and me holding the throttle wide open at only 2000 rpms. Does that sound right?
 

emdsapmgr

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Re: 1983 Johnson 150 one dry plug

The #1 high speed jet is really accessible on that engine. Why not just remove the bowl drain and pull that jet out for visual inspection? Do you use the jet removal tool when taking the jets out? If you've got a dry hole-it's getting no lubrication whatsoever. Keep your spray bottle of fuel handy and only run the engine with the bottle in hand-spraying. Does any fuel come out of the middle carb?
 

Flats

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Re: 1983 Johnson 150 one dry plug

Well i will try the spray bottle idea this afternoon if the rain lets me. To answer your question on me using the removal tool to remove the jets when i rebuilt the carbs... well lets just say i didnt remove the jets... which could be my problem.. I believe the high speed jets are the ones that you see when you remove the two flat head screws on either side of the bowl, is that correct? Maybe i should start with my version of rebuilding the carbs. I removed the carbs, opened them up , removed the float and needle valve, shot chemtool carb cleaner through all the little holes and put it back together. ( i didnt remove the little silver disc). well with that being said i may not have done all the steps i needed to.
There is no fuel coming out of the middle carb as far as out of the front of the throat. where can you get the jet removal tool at?
 

emdsapmgr

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Re: 1983 Johnson 150 one dry plug

It's best to remove the jets, so you can get a good visual on them-to check for blockage. You can get a jet removal tool from any bombardier dealership. Part number: 317002 About $ 37. I try to overhaul my carbs without removing the silver discs. Usually, I've been successful in cleaning the passages without removing them. If you remove them, the have to be re-sealed when reinstalled... Shooting carb cleaner thru the passages is the correct way-but you want to note the spray flow coming out of the other end of the passage, then compare that flow with the same passage on the other carbs. You'll catch restricted passages by comparing the outflow between the carbs.
 

Flats

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Re: 1983 Johnson 150 one dry plug

Ok I had a little time so I removed both of the flat head screws on the bottom of the bowl. I could see straight through to the other side. I pumped the bulb up , no gas came out. Not sure if it should. Then sprayed carb cleaner through the hole. Then turned the motor over and a little drip came out each side. Put the screws back in. Fired it up. Same issue dry plug. So I guess my next step is to pull the jets? Right? Clean them and repeat the test ?
 

Joe Reeves

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Re: 1983 Johnson 150 one dry plug

Ok I had a little time so I removed both of the flat head screws on the bottom of the bowl. I could see straight through to the other side. I pumped the bulb up , no gas came out. Not sure if it should. Then sprayed carb cleaner through the hole. Then turned the motor over and a little drip came out each side. Put the screws back in. Fired it up. Same issue dry plug. So I guess my next step is to pull the jets? Right? Clean them and repeat the test ?

You had the drain screws removed so that you could see the high speed jets, then pumped the fuel primer bulb up hard...... and no gas flowed out of those drain holes? That indicates that no fuel is entering that carburetor at all.... either an obstruction in the fuel hose or a very stuck/jammed float needle valve.
 

Flats

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Re: 1983 Johnson 150 one dry plug

You had the drain screws removed so that you could see the high speed jets, then pumped the fuel primer bulb up hard...... and no gas flowed out of those drain holes? That indicates that no fuel is entering that carburetor at all.... either an obstruction in the fuel hose or a very stuck/jammed float needle valve.

Hmm yes that's correct. Ill pull the carb in the morning and tell you what I find .
 

Flats

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Re: 1983 Johnson 150 one dry plug

Ok pulled carb and found that one of the two jig speed jets was not in the carb. Also found the little holder clip for the needle and seat was not there. Going to fix both issues and let everyone know what happens.
 

Joe Reeves

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Re: 1983 Johnson 150 one dry plug

Ok pulled carb and found that one of the two jig speed jets was not in the carb. Also found the little holder clip for the needle and seat was not there. Going to fix both issues and let everyone know what happens.

What is a "jig speed jet"?
 

Flats

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Re: 1983 Johnson 150 one dry plug

What is a "jig speed jet"?

Sorry I meant high speed jet. But I found out what the problem was. I thought I was missing a high speed jet but I found out that someone put both high speed jets on one side of the carb. I missed it when I rebuilt them. So I went through all three carbs again. I also found that I didn't put the little metal clip on any of the floats. The clip that returns the needle from the seat. So I put them on as well. Now on the hose it sounds like a v6 and not a weed eater. Hahaha. Ill let everyone know how it goes after I run it tomorrow.
 

Flats

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Re: 1983 Johnson 150 one dry plug

ok i wanted to send an update out and tell everyone thanks for the support! After putting the jets back where they belong in the top carb, the boat did perform very well.... I think for a motor that has not ran in 15 years it did do good ( and was a free motor). It is on my 1975 Mako 23 center console which weighs 2550 for just the hull ( dead-rise is only 12 degrees ). after using two seperate GPS's at the same time, it did run 39 mph WOT which was only turning 4200 rpm's because of the 14 1/2 X 21 prop. I do have a 14 1/4 X20 that i will try next... I was surprised because the previous owner and I didnt think it would even get on plane. Actually the day i ran it I was given a 1993 Mercury 200 2.5L carbed motor (free LOL) that runs perfect and is some sort of racing motor ( has racing on the cowl and the pointed lower unit - Still have to run the number).. So i will be trying the Merc next once i have located controls ect..
 

emdsapmgr

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Re: 1983 Johnson 150 one dry plug

You'll pickup about 150 rpm's with the 20 pitch. RPM's are still too low for that engine. You want it to turn at least 5500, so I'd be looking to try a 17. Will pickup hole shot and probably some mph also. Once you try the 17, you'll find out if you need to go to an even lower pitch.
 

Flats

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Re: 1983 Johnson 150 one dry plug

Ok here we go. I changed out the prop and went down from the 14 3/4 X 21 to a 15x15. I can get it up to 5200 rpms. Went from 39 with the 21 to 36 but runs way better. It seems the motor does love gas! Ran it about 5 mile in a bayou smooth water , 5-10 wind and three 200lb men, burned 8 gallons in 5 miles. Does that sound right? Basically I think the 150 is just too small to get the job done. Let me know your thoughts.
 

emdsapmgr

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Re: 1983 Johnson 150 one dry plug

Your 15 pitch is much better, but you are still low on rpm's. That engine should run right at 5500 for best fuel economy and performance-you are off about one prop size now. Before you swap props, check your engine setup (height on the transom.) The engine has an extra long lower unit on it. If you have a lot of water spray from the engine while on plane, it might be mounted too low on the transom. If so, that will cause a lot of drag and lousy fuel economy. The crossflow engine line doesn't get very good fuel economy.
 
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