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1987 Johnson 90hp problems

C

Copenhagen

New member
I'm new to the world of boat motors. Having no prior experience or knowledge I've relied upon threads and information I can obtain to learn thus far. Any advice will be greatly appreciated!

My reverse will not engaged when I attempt to shift it into gear, all that happens is that it will immediately start making a loud clicking sound. Shifts fine into forward. After researching and watching videos I feel like it's potentially the clutch dog, reverse gear, or rod that runs down to the lower unit to actually engage the gears.

Secondly, when idling my motor doesn't seem to like it too much. It will periodically make a thud sound and you can certainly feel it when it happens. It will also die on its own after I've ran up the lake to where I want to start fishing once I put it into neutral. It doesn't die instantly but within 5-6 seconds it will. I don't know if these two are potentially attached to the same problem but I've seen where faulty fuel pumps can cause very similar symptoms.

Lastly, sometimes when I push it to full throttle it will only jump up to 2900 rpms when it usually jumps up to about 3800 rpms and will not plain out at all. After I just idle around or shut it off and try again later it will act normally. Also, while running wide open which is usually at 40mph it will all of a sudden die down and decrease to approximately 30 mph. I honestly haven't the slightest clue as to what would be causing this.

ive read a number of posts on here and feel that quite a few people on here seem to be quite knowledgable and I really hope someone can shed some light on these problems, thanks!
 
Start with the basics if for no other reason to eliminate problem areas.................

Remove all spark plugs, take a compresssion check. What are the psi reading of all cylinders?

With the s/plugs still removed, rig a spark tester where as you can set a 7/16" gap for the spark to jump. The spark should jump this gap with a strong blue lightning like flame... a real SNAP! Does it?

The above two areas have nothing to do with your shifting problem... BUT... it is the trouble shooting starting point and shouldn't be ignored. If a piston is failing and compression is down 30 psi on one cylinder, it's something you should be aware of before putting $$$ in a lower unit rebuild.

If the above two areas (compression/ignition) are as they should be, remove the shift cable from the engine's linkage so that you can shift the lower unit into gear by hand with the engines linkage (what the cable was attached to). If this cures the shift problem, the cable is not adjusted properly, see the following.

(Centering Shift Cable)
(J. Reeves)

When all is as it should be, the proper method to adjust the shift cable is to disconnect the cable from the engine. Move the shift linkage on the engine to find the center of the play in neutral, and when found, leave it centered.

Now, grab the end of the shift cable sleeve, push and pull it to find the center of the play there, and center that play.

Adjust the trunion on the threaded portion of the shift cable so that the centered play of the cable lines up with the centered play of the engine's shift linkage. Install and lock the shift cable with the retaining clamp in that position. That's it.

**********

If on the other hand, shifting the linkeage by hand makes no difference... I would suspect that someone has had the lower unit off and turned the shift rod out of adjustment. The measurement from the top of the lower unit surface to the center tof the shift rod hole (in neutral) is critical. I don't have the specifications for the 1987 model but the 1986 90hp is as follows and is most likely identical. If not, I'm sure some other member will jump in here with those specs.

1986 - 90 thru 110hp = (L) 21-27/32" - - (XL)26-27/32" plus/minus 1/32". Have shift rod in neutral.

The rpm at idle/neutral dropping to a shut down scenario... I suspect that the linkage is also set improperly, that is the idle stop screw is not set up against the crankcase stop which would allow the engines linkage vibrate past (below) the initial idle setting. (A starting point).
 
I have a 1981 15hp Johnson that does the same thing "put into neutral, It doesn't die instantly but within 5-6 seconds it will"
I'm not a mechanic (just a girl that like's to go fishing)
It also "jumps up" when put into Reverse, seems like it should be locked in somehow???
 
Last edited:
joereeves said:
Start with the basics if for no other reason to eliminate problem areas.................

Remove all spark plugs, take a compresssion check. What are the psi reading of all cylinders?

With the s/plugs still removed, rig a spark tester where as you can set a 7/16" gap for the spark to jump. The spark should jump this gap with a strong blue lightning like flame... a real SNAP! Does it?

The above two areas have nothing to do with your shifting problem... BUT... it is the trouble shooting starting point and shouldn't be ignored. If a piston is failing and compression is down 30 psi on one cylinder, it's something you should be aware of before putting $$$ in a lower unit rebuild.

If the above two areas (compression/ignition) are as they should be, remove the shift cable from the engine's linkage so that you can shift the lower unit into gear by hand with the engines linkage (what the cable was attached to). If this cures the shift problem, the cable is not adjusted properly, see the following.

(Centering Shift Cable)
(J. Reeves)


When all is as it should be, the proper method to adjust the shift cable is to disconnect the cable from the engine. Move the shift linkage on the engine to find the center of the play in neutral, and when found, leave it centered.

Now, grab the end of the shift cable sleeve, push and pull it to find the center of the play there, and center that play.

Adjust the trunion on the threaded portion of the shift cable so that the centered play of the cable lines up with the centered play of the engine's shift linkage. Install and lock the shift cable with the retaining clamp in that position. That's it.

**********

If on the other hand, shifting the linkeage by hand makes no difference... I would suspect that someone has had the lower unit off and turned the shift rod out of adjustment. The measurement from the top of the lower unit surface to the center tof the shift rod hole (in neutral) is critical. I don't have the specifications for the 1987 model but the 1986 90hp is as follows and is most likely identical. If not, I'm sure some other member will jump in here with those specs.

1986 - 90 thru 110hp = (L) 21-27/32" - - (XL)26-27/32" plus/minus 1/32". Have shift rod in neutral.

The rpm at idle/neutral dropping to a shut down scenario... I suspect that the linkage is also set improperly, that is the idle stop screw is not set up against the crankcase stop which would allow the engines linkage vibrate past (below) the initial idle setting. (A starting point).
Click to expand...

This info helps me out a lot. I've had this boat for about 8 years and even though its been ran each year at least 3-4 times I've just now started using it about 3-4 days a week to fish. I'm going to try each of the things you suggested tomorrow. i have to go and get my carb tester from our storage building.

I'm about to go out now to see if it will shift into reverse by hand, hopefully the cable is my problem. also, i don't know if this has any significance in regards to the reverse issue I'm having but i put the ears on it the other day and tried to see if it would go into reverse and it still clicked the whole time but the prop was moving in the reverse direction which is odd to me. But, after you explaining the cable being out of adjustment it would make more sense that it is indeed that.

My main concern and question that I have asked numerous people and mechanics is whether or not its worth putting the money into this motor if it is the lower unit? One mechanic i talked to said that his best guess would be that i would have $1000 in parts alone.

I'll let you know what happens after i try this out. do i need to have the motor running when i try to put it in reverse by hand?
 
(You asked "I'll let you know what happens after i try this out. do i need to have the motor running when i try to put it in reverse by hand?")

No... When shifting into gear without having the engine running, simply spin the prop with your foot so as to have the shifter dog lobes align with the gear lobes properly.

However, this will not tell you anything really. You need to shift that linkage by hand while in the water under way to find out if it responds properly or not.

I wonder....... There are boaters who shift into gear very slowly, thinking that they're taking it easy on the engine and shifting components (big mistake). Such thinking allows the edges of the shifter lobes to clank together many time before actually shifting into gear. The proper method to use when shifting is to slam the engine into gear as quickly as possible in order to avoid having those shifting lobes clanking and rounding off at the edges.
 
joereeves said:
(You asked "I'll let you know what happens after i try this out. do i need to have the motor running when i try to put it in reverse by hand?")

No... When shifting into gear without having the engine running, simply spin the prop with your foot so as to have the shifter dog lobes align with the gear lobes properly.

However, this will not tell you anything really. You need to shift that linkage by hand while in the water under way to find out if it responds properly or not.

I wonder....... There are boaters who shift into gear very slowly, thinking that they're taking it easy on the engine and shifting components (big mistake). Such thinking allows the edges of the shifter lobes to clank together many time before actually shifting into gear. The proper method to use when shifting is to slam the engine into gear as quickly as possible in order to avoid having those shifting lobes clanking and rounding off at the edges.
Click to expand...

From what i understand putting the ears on it and actually having it in the water aren't the same thing at all because when you're actually in the water there is pressure on the motor from being submerged. Is this correct?

Also, to answer your last statement i actually was doing that when it first started the clicking because I didn't know any different. Later I found out that it was actually just rounding off the gears like you said. This is also a major concern for me because something that could have been a simple fix has now potentially turned into a costly one.If so i guess this one is going to be chalked up to inexperience ( also known as stupidity) haha.

i know that the fuel lines and fuel filter have never been changed on it either and i will be changing them over the winter but could some of the problems that i have with it cutting out at high rpms be a fuel issue? also the shifter mounted by the steering wheel has been worked on and the guy said that he fixed it back to where it needed to be but it was in serious need of being replaced due to the use over the years. this is also something i will be replacing this winter. the trim up button on it has essentially gotten to the point to where i have to push with quite a bit of pressure to get it to actually trim the motor up, even though I'm sure thats just do to the spring behind the button assuming that they are spring loaded. Like i said I'm new to this whole marine engine business and I'm just trying to cover all my bases and pick anyones brain about all the possibilities that could be causing my motor troubles.
Thanks again!
 
Copenhagen said:
From what i understand putting the ears on it and actually having it in the water aren't the same thing at all because when you're actually in the water there is pressure on the motor from being submerged. Is this correct?

(Slow Shifting) I actually was doing that when it first started the clicking because I didn't know any different. Later I found out that it was actually just rounding off the gears like you said.

Could some of the problems that i have with it cutting out at high rpms be a fuel issue?

Also the shifter mounted by the steering wheel has been worked on and the guy said that he fixed it back to where it needed to be but it was in serious need of being replaced due to the use over the years.

The trim up button on it has essentially gotten to the point to where i have to push with quite a bit of pressure to get it to actually trim the motor up
Click to expand...

In the water, running and in gear, there is back pressure on the propeller, shifter dog lobes and also the gear lobes. This condition does not exist when running on a flushette.

Yes, that slow shifting habit leads into expensive repairs.

Cutting out at high rpms could be an ignition problem (usually a very sharp change in rpms)... OR... a fuel problem if the drop is a gradual, even a fast gradual one. Does pumping the fuel primer bulb, acting as a manual fuel pump, make any kind of difference?

This is why I stated to do a compression and spark test before doing anything. Keep in mind that the 7/16" gap pertaining to the spark test is important. It determines (hopefully) whether the problem is "Ignition", a "Fuel" problem, or possibly a failure of some mechanical engine component.

You say that someone has worked on the control box assy... Hmm, If your shifting problem didn't exist previously, I would wonder if the unit was repaired properly (cable adjustments).

The tilt switch cannot be repaired... replace it.

(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
 
joereeves said:
In the water, running and in gear, there is back pressure on the propeller, shifter dog lobes and also the gear lobes. This condition does not exist when running on a flushette.

Yes, that slow shifting habit leads into expensive repairs.

Cutting out at high rpms could be an ignition problem (usually a very sharp change in rpms)... OR... a fuel problem if the drop is a gradual, even a fast gradual one. Does pumping the fuel primer bulb, acting as a manual fuel pump, make any kind of difference?

This is why I stated to do a compression and spark test before doing anything. Keep in mind that the 7/16" gap pertaining to the spark test is important. It determines (hopefully) whether the problem is "Ignition", a "Fuel" problem, or possibly a failure of some mechanical engine component.

You say that someone has worked on the control box assy... Hmm, If your shifting problem didn't exist previously, I would wonder if the unit was repaired properly (cable adjustments).

The tilt switch cannot be repaired... replace it.

(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
Click to expand...

just finished up doing a compression test and spark test.
Compression test came back as follows: Left Bank Top- 115, Left Bank Bottom-105, Right Bank Top-110, Right Bank Bottom-110
Spark test came back fine for the Right Bank both top and bottom, had strong blueish white lightning like pulses. Left bank although didn't have any spark whatsoever. Could this be a Coil Pack issue?

Also i put the ears on the motor to run it before starting the compression and spark test and it would go into gear but once i started giving it more throttle it would just simply click and the prop would spin in the reverse direction.
 
i forgot to mention that the motor started up and ran which confuses me if its only getting spark in two cylinders, wouldn't it be running rough or at all?
The motor has been running very rich, you can smell and see how rich it is running when you fire it up.
 
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