1988 Johnson 90HP V4 issues

TuffTurkey

Cadet
Joined
Jun 7, 2020
Messages
6
I've bought a boat my first and water tested it and worked flawlessly. However, once in my possession the outboard has refused to operate normally. I have fixed the idling issue, cleaned carbs, changed spark plugs and ignition coils (they were cracked).

Anyways fixed some issues. One day I went out with my brother, and I am going to explain this as much as I can. We left the dock and in the no wake zone it ran fine at idle, then when I went to give her power, I got up to 2000 rpm she tried to plane and then over rev. My first thought was spun prop! I went out and got a new prop and hub kit (brand new). When I took out the old, i could see cracks in the old hub, hooray I was right! Removed a little bit of fishing line and re greased and reinstalled. Got back on the water and same thing, 2,000 rpm and over rev not going anywhere losing power until I backed off. Well, one thing I did was try again but adding power slowly once i got to the 2000 rpm range I heard a clunk not a grind almost the sound when your trailer connecter falls onto the hitch ball. Once that happened she started to speed up to what she can do at wot (25 mph with a 16 foot center console with just me and brother, seems strange) We went about a quarter mile and then I slowed down to see if the problem would persist. Well this time I could only go about 5-10 knots (being liberal speedo didnt pick this up) by the time i was approaching the no wake zone I realized i was in WOT but only going that speed. After flushing out the outboard, I pulled the lower unit and my water pump and everything was covered in this grease, Im thinking water and oil that turned into sludge.


My question is, is this my lower unit failing? After seeing the sludge thinking it blew every seal, because the prop leaked oil after I got her out.


I want to get this fixed as I have not been out on the water with her and i did all the checks that i could before purchasing. This just has me baffled. I hope it is simple a replacing the lower unit. and not a new engine because that would be more than i bought the boat for :(

Thank you in advance. Boat model number is J90TLCCA
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,421
Is oil injection in service ?---Checked out and mixing properly ?----Or mixing at 50:1 in your fuel tank ?
 

TuffTurkey

Cadet
Joined
Jun 7, 2020
Messages
6
Is oil injection in service ?---Checked out and mixing properly ?----Or mixing at 50:1 in your fuel tank ?

I think in the beginning I was mixing it too rich for one tank. ( 9 gallon tank) but then went to 50:1 in my tank. It seems that the oil injection has been bypassed/Removed
 

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
You should do 40MPH with that rig.
Were you trimmed down? If you're trimmed into the tilt zone they will overcome the tilt cylinder & clunk when it drives down.
Over trimmed could account for the prop losing grip???
The oil & sludge sounds like it's not running on all 4 cylinders.
They will run fine with double oil FWIW.

I'd start with a compression test & test each cylinder for spark with an air gap tester.
 

TuffTurkey

Cadet
Joined
Jun 7, 2020
Messages
6
You should do 40MPH with that rig.
Were you trimmed down? If you're trimmed into the tilt zone they will overcome the tilt cylinder & clunk when it drives down.
Over trimmed could account for the prop losing grip???
The oil & sludge sounds like it's not running on all 4 cylinders.
They will run fine with double oil FWIW.

I'd start with a compression test & test each cylinder for spark with an air gap tester.

Oil and sludge in the lower unit would cause that? I was thinking I blew seals. But I will redo a compression check and test cylinder for spark.
 
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