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1989 Johnson 110 will not accelerate.

Jrod26

New member
Hello,

I have a 1989 Johnson 110 2 stroke on an 18' VIP. It will not go faster than 6 mph. In previous years it would do 30 mph. At the end of last summer it was running rough so a local shop replaced the reeds and went through the carbs. It ran like a top after that. It has a new prop and lower unit, compression is 105-110 on all cylinders and has good spark. In neutral, it will rev up and fuel pressure increases appropriately so I think the carbs and fuel diaphragm are still working as they should. In gear it will only accelerate to 6mph. As I continue to throttle up over 6mph it begins to vibrate. We replaced the lower unit this week thinking that was the cause of the vibration to no avail. Any ideas what could cause the lack of power or any other diagnostics I can check?

Thanks in advance!
 
Hello,

I have a 1989 Johnson 110 2 stroke on an 18' VIP. It will not go faster than 6 mph. In previous years it would do 30 mph. At the end of last summer it was running rough so a local shop replaced the reeds and went through the carbs. It ran like a top after that. It has a new prop and lower unit, compression is 105-110 on all cylinders and has good spark. In neutral, it will rev up and fuel pressure increases appropriately so I think the carbs and fuel diaphragm are still working as they should. In gear it will only accelerate to 6mph. As I continue to throttle up over 6mph it begins to vibrate. We replaced the lower unit this week thinking that was the cause of the vibration to no avail. Any ideas what could cause the lack of power or any other diagnostics I can check?

Thanks in advance!
any chance of getting RPM instead of MPH?
Is your spark advancing?
Are your throttle plates opening all the way?
Is it running on all cylinders?
Same size prop?
Vibrate or exstream shaking?
 
Post recent compression numbers.------Does spark jump a gap of 7/16" or more on all leads , yes or no ?----Checked the flywheel key ?-------Run with a timing light to see if spark behaves properly.----Checked for water in the fuel ?-----Test run with cover off.------Test run with a portable fuel tank and another hose.----Some will argue ---For me and on my compression tester that motor would becoming apart for rebuild.------105 PSI simply is no good !!!
 
None of the guages on the boat have worked since I bought it so I do not have RPMs. I get speed from the depth finder.
Throttle plates are opening.
I have not put a timing light on it yet, but will add that to the to do list.
All cylinders get warm during test so I velo all are working.
Same prop size.
I would say vibration. It's enough to feel it in the floor of the boat but not extreme by any means.

Compression was tested when I bought it a few years back and they are written on each cylinder either 105 or 110. I checked it last weekend and they still match those numbers.
Yes spark is adequate, checked last weekend too.
We ran the fuel out at the end of last summer and used new gas this year so I imagine it's fine.
Have not checked flywheel key yet.
It runs flawless in neutral and in gear at low speeds.
 
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Post recent compression numbers.------Does spark jump a gap of 7/16" or more on all leads , yes or no ?----Checked the flywheel key ?-------Run with a timing light to see if spark behaves properly.----Checked for water in the fuel ?-----Test run with cover off.------Test run with a portable fuel tank and another hose.----Some will argue ---For me and on my compression tester that motor would becoming apart for rebuild.------105 PSI simply is no good !!!

Racer....he's not using your guage. My Snap-On compression guage has never shown over 120 psi on ANY engine for the past thirty years. Dozens of different engines. 105 to 110 is typical on it
 
Trouble shooting on these engines is EXTREMELY easy.----Most folks today struggle with the concept of a 2 stroke engine.----Not to worry.----Tesla battery powered boats are in the future.----Just spend the money.----Push the button and go top speed.
 
My Snap-On compression guage has never shown over 120 psi on ANY engine for the past thirty years
Not picking on ya but when is the last time you checked calibration on it...yes they can be calibrated. I have all my torque wrenches, gauge style testers recalibrated every 2 years at aircraft shop. The gauges pulse bounce tweeks the gears/levers inside over time.
 
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Not picking on ya but when is the last time you checked calibration on it...yes they can be calibrated. I have all my torque wrenches, gauge style testers recalibrated every 2 years at aircraft shop...

It occurred to me but no need. It's always read low but it's consistent. A number only has the meaning you put on it.
 
None of the guages on the boat have worked since I bought it so I do not have RPMs. I get speed from the depth finder.
Throttle plates are opening.
I have not put a timing light on it yet, but will add that to the to do list.
All cylinders get warm during test so I velo all are working.
Same prop size.
I would say vibration. It's enough to feel it in the floor of the boat but not extreme by any means.

Compression was tested when I bought it a few years back and they are written on each cylinder either 105 or 110. I checked it last weekend and they still match those numbers.
Yes spark is adequate, checked last weekend too.
We ran the fuel out at the end of last summer and used new gas this year so I imagine it's fine.
Have not checked flywheel key yet.
It runs flawless in neutral and in gear at low speeds.

Could it have a spun prop?
 
Brand new prop and hub. I thought that could be the issue so I replaced it. The prop had some wear so I figured I would just replace it.
 
Are throttle plates opening ALL The WAY?
Is it running on all four cylinders?
Is the spark advance lever moving?
Can you do some of Racers test?
If this is too difficult or you dont know how,ask.
Check your fuel fore contamination,dont assume anything.
 
So I've tried running it with and without the cover, tried new gas in a new gas can and fuel line and it still runs smooth at all RPMs. It fires as soon as you turn it over and purrs like a kitten as you increase throttle. As such, I imagine it is not missing and I can rule out bad fuel. I took it out for a second time since the new lower unit install this past weekend. It is smooth at low RPMs but as increased throttle it began to vibrate which then turned into a shake at even higher RPMs. I still have not figured the tach out so I don't know exact RPMs but can tell it is increasing with throttle. I got back home and the gear lube was running out of the lower unit seals. Clearly the vibration/shaking is beating up the seals. Could whatever spins the driveshaft be damaged causing it to move around?
 
The seals were leaking and I figured the issue was attributed to the gears slipping. It is only a few years old and still under warranty. Resealing it myself would void the warranty so I sent it back and they sent me a new one.
 
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