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1997 Johnson 90 spl

Old 05-17-2020, 08:58 PM
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Default 1997 Johnson 90 spl

My 1997 Johnson 90 spl is only running on the bottom 2 cylinders. I took it out a few days ago and it took me forever to get it started. Once I got it started it wouldnít stay running. Finally I got it to stay running but it wouldnít go over 2000 RPMís. If I unplugged the top 2 plugs it made no difference in how it ran. If I unplugged either of the bottom 2 plugs it would die. Now I canít get it to run at all. Anyone have any advice? Thanks!
Old 05-17-2020, 09:07 PM
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First step is to check spark properly, I think I see a carb clean in your future though.
Old 05-17-2020, 09:16 PM
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Iím checking compression and spark tomorrow. I know they are sparking because they bit me when I unplugged them. lol. Iím still going to check the spark tomorrow tho. I had a feeling I was going to have to clean the carbs. Just need some affirmation on what I was thinking. Thanks
Old 05-17-2020, 09:22 PM
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You need to do some very basic trouble shooting, spark, compression and so on, check the plugs when you remove them and post what they look like.
Old 05-18-2020, 03:06 AM
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Did you inherit this problem or did this just start happening? Wondering if a PO was in there and mixed up the plug wires? Just because they bite you, doesn't mean it bit you at the right time! B-)

If the top two cylinders aren't getting fuel though.....well, just rebuild both carbs. You'll be glad you did!
Old 05-18-2020, 08:43 AM
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I inherited the problem. When I bought the boat it started and ran fine multiple times with ears and water hooked up. The fuel gage didnít work so I bought an aftermarket sending unit from Bass Pro. The screw holes didnít line up exactly right and it was leaking a little fuel around the sending unit after I filled the tank. I thought it might be air in the line because I had to keep pumping the bubble every few minutes. I bought a new external tank and a new fuel line. It helped it to stay running but it still only ran 2000 RPMís. Iíll post the pics of the plugs shortly. As soon as it stops raining Iíll pull them. Thanks!
Old 05-18-2020, 08:54 AM
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Power pack.

Do not make the very common mistake of buying an aftermarket one, buy OEM.
Old 05-18-2020, 08:59 AM
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Hopefully it is a spark problem. No fuel = no oil. Continued operation in that scenario will likely get expensive.
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Old 05-18-2020, 11:26 AM
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Originally Posted by Ronaldp12 View Post
The fuel gage didnít work so I bought an aftermarket sending unit from Bass Pro. The screw holes didnít line up exactly right and it was leaking a little fuel around the sending unit after I filled the tank.
The screw pattern looks symmetric, but it isn't. Two of the holes are off a few degrees. Remove the sending unit and then use the gasket only to line the 5 screws up - there are 4 wrong orientations and only 1 correct one. Mark the gasket and the tank with a sharpie, remove the gasket and align with sending unit. Now the holes in the tank, gasket, and sending unit should be aligned.

Concerning lack of spark, my bet is a bad stator under the flywheel. There are two sets of coils - one for spark and one for charging, check resistance for starters, specs should be online.
Old 05-18-2020, 11:55 AM
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Originally Posted by louiefl View Post
The screw pattern looks symmetric, but it isn't. Two of the holes are off a few degrees. Remove the sending unit and then use the gasket only to line the 5 screws up - there are 4 wrong orientations and only 1 correct one. Mark the gasket and the tank with a sharpie, remove the gasket and align with sending unit. Now the holes in the tank, gasket, and sending unit should be aligned.

Concerning lack of spark, my bet is a bad stator under the flywheel. There are two sets of coils - one for spark and one for charging, check resistance for starters, specs should be online.

Thanks, Iíll check that too.
Old 05-18-2020, 01:26 PM
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Not sure why some are assuming no spark when he hasnít even checked it yet and said when he pulled a lead he got bit !
Old 05-18-2020, 01:57 PM
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Default Plug Wires

My first boat had a 88 SPL on it. Had same issue but only running on 3 cylinders. Was a dog to get on plane. Seller thought it was a serious issue so I got it at a good price.
Changed out spark plug wires and never had a another issue with it for 2 years til it lost the rings on the bottom cylinder.

Take the plug wires off the cylinders you know are firing and move over to the other. You can figure out quick it thatís your issue.
Old 05-18-2020, 05:09 PM
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I sprayed carb cleaner in the carbs and then blew it all out with compressed air. I also removed and cleaned the plugs. I did a compression test also. The results were 119, 120, 122 and 123. After all of that I started it and it idled with a small miss. I took it to the water and it ran very good at high rpmís but at an idle or slightly above an idle it has a noticeable miss. Iím sure taking the carbs off and doing a thorough cleaning would take care of that.
Old 05-18-2020, 06:14 PM
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Please listen very carefully.

That motor has 2 carbs.
The upper carb is for the upper cylinders, the lower is for the lower cyclinders.

The carbs deliver the fuel AND the oil. Regardless of whether or not you premix the oil.

if a carb is having problems, it is NOT delivering oil.

Running it at high rpms only uses the power of the working half of the motor to spin the not running (and soon to be trashed )other half of the motor.

Please don't run it if you're not 100% sure it's not the carbs.

PM me if you need more details as to what happened to my OMC 90 hp.
Old 05-18-2020, 08:42 PM
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Originally Posted by Ronaldp12 View Post
I sprayed carb cleaner in the carbs and then blew it all out with compressed air. I also removed and cleaned the plugs. I did a compression test also. The results were 119, 120, 122 and 123. After all of that I started it and it idled with a small miss. I took it to the water and it ran very good at high rpmís but at an idle or slightly above an idle it has a noticeable miss. Iím sure taking the carbs off and doing a thorough cleaning would take care of that.
from that description, you didn't clean the carbs, you made them look nice, what did the plugs look like in each cylinder?

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