99 Johnson 115 won't idle after running

[docgreen9]

Hi ... posted here a while back on this engine. Needing some advice on it again. My original problem and post HERE Well that problem was fixed. Ended up taking it to the dealer for the cutting out issue. They threw all kinds a parts at it. Calling it fixed after every trip. They replaced Fuel Pump, Oil Injection system, and Rebuilt the carbs. Now since these repairs the motor will start and run normal when cold. Drive it 5-10 miles on the water. Shut it down and site for an hour, two, or so fishing. Go to start it and it won't stay running long enough to get it in gear. If you do get it in gear it'll just die. It'll take 15-20-30 tries to remedy and get it going barely then it'll kick in fine and be good till stopped again and let sit. Here is a list of parts replaced :

Plugs, wire, coils, carbs(rebuilt), VRO, fuel pump, IGN module, primer bulb, fuel lines ( to motor ) and all filters. Timing has been done several times, carb timing. Pretty much everything.

Now after telling us that the compression was great, 145-150 all cyls, all four trips to the shop. I'm getting that the piston skirts are worn and not creating enough vacuum in the crank case for the fuel pump to work at idle or low RPM. Something about Johnson having a "Special" skirt for vacuum.

Now I'm no expert on 2-strokes but I do know a few things and I'm thinking I'm gonna have to raise the BS flag on this. How can my compression be great and the cyl's be worn enough to not work the pump correctly??? Can someone explain to me how that would work??

Thanks .. just need some ideas. After 8 years of fantastic service from this motor is it just at the end of it's life?

Thanks,
Brian

 

[prh3]

Re: 99 Johnson 115 won't idle after running

Brian,

I have a 1997 150 that does the same exact thing as your motor. From a cold start the motor idles and runs like a top at all speeds. Back to idle in gear I can go all day. But after I stop to visit or fish for an hour or so it starts fine but stalls when I put it in gear. I have found that the only way to get going is when I throw it in gear to feather or slightly pump the throttle back and forth until the rpms start to pick up. Then once it reaches 1000 rpm or so it runs great. After running at 1000-1200 for a minute or so, I can throttle back to idle and it then runs fine.
If you ever find out what the problem is I hope you can tell me and I will do the same if I crack the case first.
prh3

 

[CharlieB]

Re: 99 Johnson 115 won't idle after running

Both of you guys,

Have you tried squeezing the primer bulb before restarting? Does that make a difference?

I've found two 115's that heat soak would boil off just enough fuel that they would only idle until the fuel pump completely filled the carbs.

 

[docgreen9]

Re: 99 Johnson 115 won't idle after running

CharlieB ... yes that was the first thing we tried. We even replaced it anyhow just for giggles.

prh3 .... I feel your pain. This thing has drove me nuts. Finally took it to the shop. They're not much better than me. First they said it was the carbs and rebuilt them, then the fuel pump oil injector assembly, then it was just adjusting the prior repairs, then all of a sudden it needs a rebuild ( of course ). When they took it apart they told us the main center seal that separated the two sides of the motor was cracked in many places letting causing poor vacuum after heat soak and not letting the fuel pump work properly. Well after having it over a month it was finally done. It does run better but guess what!! Now after I let it sit after running it'll travel about 15 yds and bog down and die. Amazing!! This is my father in laws boat and I told him to ditch this motor and get a verado or something. Guess it's back to the shop under warranty again. Hope you have better luck. It's sad it was a worry free motor for 7 years.

 

[Chris1956]

Re: 99 Johnson 115 won't idle after running

Doc and Charlie, You might check the two wire heat sensor on the port cylinder head. The sensor tells the powerpack when the motor is cold, in order to activate the Quickstart feature. A simple resistance test should tell you if it works OK. This could be the cause of the hard to start after sitting a bit.

 

[prh3]

Re: 99 Johnson 115 won't idle after running

Both of you guys,

Have you tried squeezing the primer bulb before restarting? Does that make a difference?

I've found two 115's that heat soak would boil off just enough fuel that they would only idle until the fuel pump completely filled the carbs.

CharlieB,
I have got to say that I haven't tried squeezing the primer bulb on these occasions. I only prime it when I put it in the water. It will cold start everytime even after sitting for a couple days in the dock and run fine until I stop with a warm engine for a while. I will try your suggestion next spring and see if that does the trick for me. Could you explain what "heat soak" is so i could understand what may be happening. Another guy called it "hot soak" on another board.
THX
prh3

 

[prh3]

Re: 99 Johnson 115 won't idle after running

Doc and Charlie, You might check the two wire heat sensor on the port cylinder head. The sensor tells the powerpack when the motor is cold, in order to activate the Quickstart feature. A simple resistance test should tell you if it works OK. This could be the cause of the hard to start after sitting a bit.

Chris1956,

Our problem is not that it won't start but won't stay running when in gear at idle. Also this problem does not happen on cold start but on warm start up. My Quickstart works for sure as I get a fast idle for a minute or so when the engine has set overnight and a fast idle for a few seconds on the warm starts which is normal Quickstart operation according to the manual.

THX
prh3

 

[prh3]

Re: 99 Johnson 115 won't idle after running

CharlieB ... yes that was the first thing we tried. We even replaced it anyhow just for giggles.

prh3 .... I feel your pain. This thing has drove me nuts. Finally took it to the shop. They're not much better than me. First they said it was the carbs and rebuilt them, then the fuel pump oil injector assembly, then it was just adjusting the prior repairs, then all of a sudden it needs a rebuild ( of course ). When they took it apart they told us the main center seal that separated the two sides of the motor was cracked in many places letting causing poor vacuum after heat soak and not letting the fuel pump work properly. Well after having it over a month it was finally done. It does run better but guess what!! Now after I let it sit after running it'll travel about 15 yds and bog down and die. Amazing!! This is my father in laws boat and I told him to ditch this motor and get a verado or something. Guess it's back to the shop under warranty again. Hope you have better luck. It's sad it was a worry free motor for 7 years.

Docgreen9,

I have seen that happen with this engine too. I had another problem that added to all these idle problems that you may check. I had a bad shift switch which is located under the shift linkage at the motor. It kills 3 of my 6 cylinders momentarily whenever you go in and out of gear to give you smooth shifts. My switch was staying on sometimes which gave me a really low idle speed with only 3 cylinders firing. I disconnected it and thought I had found my problem but it ended up just being part of my problem. I found this out by checking spark on all the wires and found that my port side bank was not firing until I unplugged the shift switch. Just a thought for something you can check easily. I just left mine unplugged and it still shifts fine.

I just came across some good info and will copy it below. This may be what's happenning to us.


Welcome to iboats. The syptoms you are describing are classic "heat soak". Seahorse5 explains it best, and this is what he wrote in a previous post.

"You are describing the classic symptoms of heat soak. When the motor is shut off, the residual engine heat increases under the motor cover to as high as 200?F according to factory tests. The gasoline in the carbs and vapor separator tank "boil" away as the motor sits and heat is transferred from the hot cylinder block to the carburetors and fuel system.

When you restart the motor, it is actually running on the heavy vapor fumes and not on liquid gasoline. As fresh gas is pumped into the motor, the temperatures of the carburetor bodies "flash off" some of the fuel, making more vapors until they cool down with air flow. The engine may idle, but will not develop any power on acceleration.

Squeeze the primer ball before starting and let the motor idle for several minutes before taking off. This allows the venturi effect of the carburetors to cool the float bowls and the intake manifolds to the point where they operate normally. Also the lower temperature gasoline from the fuel tank being pumped into the motor helps to cool things down.

The 60? engines, 90-175 hp, are more prone to heatsoak due to their compact design and the use of plastic manifolds and carburetors. They retain heat longer than the equivalent aluminum parts used in other engine models.

Alcohol and various fuel additives promote heat soak due to their lower boiling point. Winter blend fuels have more volatility to aid in cold weather starting and can also aggravate the problem. With the new 10% alcohol gasolines heat soak problems in all types of motors will increase, especially in hot weather.

You can minimize the problem by making sure your motor is in a good state of tune, using Champion QL78YC plugs gapped to .030", and adjusting the relationship between spark advance and throttle opening (sync & link) to occur at the exact same time, and perhaps richen up the idle screws by an additional 1/2 to 1 turn out. With these suggestions and letting the motor idle for a while after restarting, you should be in good shape."


prh3

 

[Chris1956]

Re: 99 Johnson 115 won't idle after running

Prh3 makes a good point. I hadn't considered heat soak, but it fits the symptoms. I see this issue on my 60* V6 sometimes, after sitting for an hour or so after a hard run. I usually advance the throttle in neutral and run the motor at 800-1000 RPM for a few minutes, until the smoke subsides. It only happens in the bay, where the water is warm(80* +), not in the ocean where the water is much cooler(<70*).

 

[fburris]

Re: 99 Johnson 115 won't idle after running

Doc and Charlie, You might check the two wire heat sensor on the port cylinder head. The sensor tells the powerpack when the motor is cold, in order to activate the Quickstart feature. A simple resistance test should tell you if it works OK. This could be the cause of the hard to start after sitting a bit.

LOL. I have the exect same problem. Can you explain the resistance tests and what to look for? Thank You so much. This is aggrivating as crap. New fuel pump, fuel lines, vacuum hoses, carb kits, and still having this issue.

 

[fburris]

Re: 99 Johnson 115 won't idle after running

Docgreen9,

I have seen that happen with this engine too. I had another problem that added to all these idle problems that you may check. I had a bad shift switch which is located under the shift linkage at the motor. It kills 3 of my 6 cylinders momentarily whenever you go in and out of gear to give you smooth shifts. My switch was staying on sometimes which gave me a really low idle speed with only 3 cylinders firing. I disconnected it and thought I had found my problem but it ended up just being part of my problem. I found this out by checking spark on all the wires and found that my port side bank was not firing until I unplugged the shift switch. Just a thought for something you can check easily. I just left mine unplugged and it still shifts fine.

I just came across some good info and will copy it below. This may be what's happenning to us.


Welcome to iboats. The syptoms you are describing are classic "heat soak". Seahorse5 explains it best, and this is what he wrote in a previous post.

"You are describing the classic symptoms of heat soak. When the motor is shut off, the residual engine heat increases under the motor cover to as high as 200?F according to factory tests. The gasoline in the carbs and vapor separator tank "boil" away as the motor sits and heat is transferred from the hot cylinder block to the carburetors and fuel system.

When you restart the motor, it is actually running on the heavy vapor fumes and not on liquid gasoline. As fresh gas is pumped into the motor, the temperatures of the carburetor bodies "flash off" some of the fuel, making more vapors until they cool down with air flow. The engine may idle, but will not develop any power on acceleration.

Squeeze the primer ball before starting and let the motor idle for several minutes before taking off. This allows the venturi effect of the carburetors to cool the float bowls and the intake manifolds to the point where they operate normally. Also the lower temperature gasoline from the fuel tank being pumped into the motor helps to cool things down.

The 60? engines, 90-175 hp, are more prone to heatsoak due to their compact design and the use of plastic manifolds and carburetors. They retain heat longer than the equivalent aluminum parts used in other engine models.

Alcohol and various fuel additives promote heat soak due to their lower boiling point. Winter blend fuels have more volatility to aid in cold weather starting and can also aggravate the problem. With the new 10% alcohol gasolines heat soak problems in all types of motors will increase, especially in hot weather.

You can minimize the problem by making sure your motor is in a good state of tune, using Champion QL78YC plugs gapped to .030", and adjusting the relationship between spark advance and throttle opening (sync & link) to occur at the exact same time, and perhaps richen up the idle screws by an additional 1/2 to 1 turn out. With these suggestions and letting the motor idle for a while after restarting, you should be in good shape."


prh3

HMMM! I think I will try this, it looks to be fitting exactly what is happening. Only, how do you adjust the relationship between spark advance and throttle opening?

 

[jonesg]

Re: 99 Johnson 115 won't idle after running

Let it idle before turning it off, test for heatsoak by removing the hood to let it cool down.

 

[Hurban96]

Re: 99 Johnson 115 won't idle after running

Did you guys ever find a fix for this problem? Ive got a johnson 150 here thats doing the same thing. Runs great but if you let it sit for a hour or so it wont start.

 

[fburris]

Re: 99 Johnson 115 won't idle after running

My motor had 90 compression on port one. As it heated up, the compression would drop to about 80. I had my motor rebuilt and this seems to have fixed the problem. Now my trim guage does not work, so I have something else to fix. LOL!

 

[zing]

Re: 99 Johnson 115 won't idle after running

Great info guys, thanks.

Trim gauge not working, I might be able to help. Same thing happens to mine form time to time There's a little plastic lever with a spring that can get gummed up. Just shoot it with some WD or CRC while moving it, it's spring loaded and should start to bounce into the up position on it's own if the spring isn't broken. Tilt the engine all the way up it's on the left while looking from the stern.

 

[fburris]

Re: 99 Johnson 115 won't idle after running

Great info guys, thanks.

Trim gauge not working, I might be able to help. Same thing happens to mine form time to time There's a little plastic lever with a spring that can get gummed up. Just shoot it with some WD or CRC while moving it, it's spring loaded and should start to bounce into the up position on it's own if the spring isn't broken. Tilt the engine all the way up it's on the left while looking from the stern.

That was the first thing I tried. I will try some more if you have anything else. Thanks,

Frank