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Am I on the right path?

J

Jdoughty

New member
Ok first post here, so go easy on me.... haha

I've got a 1983 90hp Johnson V-4 J90TLCTE that seems to be doing the lean sneeze (or that's what I think its called)... big surprise right...

Back story on when it started, coming back from the 4th of July fireworks, it was dark and low tide in an area that I wasn't familiar with.... guess what I hit? Yup a ledge with the lower unit, cracking the housing, wrecking the prop, and bending the shaft... 'twas a super fun evening... made it back to the dock at just over an idle. It would cough and jump every 1 to 5 min, sometimes 4 or 5 times back to back, but it never stalled and made it back to the trailer.

Next morning i go out to look at it and I see what looks like burnt oil running down the sides of the housing. I originally thought this was simply from being just above Idle for almost 3 hrs. Plus I see all the damage to the lower...

Come forward to this past weekend.... I swapped out the lower unit, put on a new prop, cleaned the carbs, replaced the enrichener thingy, new plugs, new wires, checked compression (125 to 132 across the board), replaced a couple fuel lines that were leaking.

I put it in some water and fire it up.... and guess what, still coughing and sneezing.... It does it at idle, at high idle, and it stalls under load...

I have a nice blue spark on all 4 plugs when out in the open.
Left cylinders seem to get hotter than the 2 on the right.
The reeds don't seem to be blowing back trough the carbs.


Gonna buy another set of plugs and try to clean the coil mounts next.

If that doesn't help thinking it could be keyway on the flywheel? or the crankcase is leaking (tho I don't see any new oil since that night)?

Any other ideas?

Thanks
-James
 
Did this kill the engine immediately or did it keep running? That sounds like you took quite a whallop when that happened so I imagine the engine internals took quite a shock too.

A sheared woodruff key on the flywheel was my first thought as I read your complete description.

I think these have forged crank shafts (somebody more knowledgeable help here!!) and if so, I don't believe you can knock these out of index. But, maybe it's possible you cracked or bent a connecting rod throwing things out of balance? The quick way to discover this is to remove the exhaust bypass covers and take a look at the internals.
 
Start with the basics regardless of the engine problem.... Compression & Spark! All s/plugs removed for both tests.

What is the psi reading of each individual cylinder?

Using a spark tester of some kind whereas you can set a 7/16" gap for the spark to jump... the spark should be a heavy blue lightning like flame... a real SNAP! No tester?... Available at any automotive store, or build the following:
********************
(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

This can obviously be modified to a 6 or 8 cylinder setup tester.
********************
If the compression and spark test are as they should be... Remove the carburetor face plate and with the engine running and that spitting back taking place... stick two fingers directly into the carburetor throat acting as a manual choke. When/if the engine smooths out somewhat, you have found a offending carburetor.

Yes I know you said you cleaned the carburetors... do the above test anyway. Let us know what you find.

NOTE: If the flywheel key sheared even by just a few thousands... the engine would be out of time and wouldn't run at all.
 
Ok, did some more digging around tonight. Tried the finger choke and it seemed to make a difference with the bottom carb. Didn't get to the store in time for plugs, but I will Friday. Key way is fine, and there's no burn marks on the stator which is nice.

Compression read warm

140 psi top right
135 psi bottom right

138 psi top left
136 psi bottom left

So tomorrow I'll pull the carbs off again and go from there.

I'mean hoping to have it back on the water this weekend as the season doesn't last much longer up here in maine.
 
Last edited:
Jdoughty said:
I don't believe there is any adjustments on these carbs? Except for jet changes at least as far as I can see.
Click to expand...
Faztbullet means to look at the linkage and make sure all butterflies are closed equally and that they are all opening in sync. You have 2 separate carburetors, the linkage that connects them has some adjustment to it. Make sure as the throttle linkage engages that you don't have variances between the top and bottom.
 
Didn't get a chance to mess with it last night, so I'm itching to get wrenching on this thing today...

I'm going to check spark with the board and nails, pull the carbs back off and double check and make sure everything is cleaned out properly, make sure linkage is correct and carbs are synced up, and put in the new plugs.... See what happens at that point.

I'll post up my findings later

Oh and if this doesn't do it, then maybe it'll be time to see if I can get the Evinrude 110 running instead.... That's been sitting for 5 years and the wiring harness is a mess from rodents, so I was waiting till this winter to attack it. Plus it only has 90 psi in all 4 cylinders (all with in 3 pounds of each other tho) so not even 100% sure that would be worth the trouble, but it'll keep me busy in the garage when the lakes are frozen...
 
Pull the flywheel and replace the key or at least turn it upside down and be sure and torque the flywheel nut to spec. Did you check engine sync between throttle opening and spark advance? On the throttle cam that opens the carbs is a mark the carbs should be fully closed until that mark reaches center of the follower roller at that point the carbs should just begin to open.
 
I went through all that already. It didn't make any difference...

Ended up pulling the head off the left side. There seems to be some excessive piston slap going on and I see a small crack at the top of the bottom cylinder. I'm thinking that the crack would be the culprit...Whats weird is that that cylinder still showed good compression!?

So I decided to just pull the 90 off.... putting the 110 Evinrude on instead... Just need to pull the VRO off and fix some wiring since the previous owner cut the plug off it, and hope for the best. I already put new gear oil in the lower, checked the water pump, cleaned the carbs, and downloaded the wiring diagram... Looks like I'll be busy the next few days haha
 
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