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1980 Johnson 85hp v4 No Power From Stop

C

canadaboy25

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Hey everyone, I have a 1980 Johnson 85hp v4 outboard which has no power from a standstill. When the boat is stopped and is put to full throttle, it takes off alright but will not go all the way to full speed. After a while, it seems as if another cylinder kicks in as the motor immediately revs up and goes to full speed. It runs at full speed perfectly fine, it is just getting to full speed which is the problem.

Initially, I thought there was a fuel problem so I cleaned both carbs out real well but it made no difference. The throttle shafts had a lot of wear between them and the carb body so I got two different carbs from a '93 90hp Evinrude and tried those. It seems to have helped it idle a little better but the full speed problem is still there. All the fuel lines are new, the fuel screen is clean, and the the pump is working well. I think I have ruled fuel out as the issue.

I put the motor on the garden hose and started it up and started pulling off spark plug wires to see if I had a bad cylinder. Removing the top right wire makes a very noticeable difference as the motor slows right down, runs very rough, and stalls eventually. The bottom right cylinder is similar, however it does not run quite as rough and doesn't usually stall. However when unplugging the top or bottom left pug wires there is basically no change at all. If you really listen there is a very slight change but nothing compared to the right side. When the wire is put back on the spark plug, the motor revs up for a split second and then back down to where it normally is. While I have the wire unplugged there is a strong spark between the end of the plug wire and the pliers I am holding the entire time and it does make a very slight difference to the way the motor runs so it's not completely missing spark.

I did a compression test and the numbers were 110, 115, 115, 120. They're not perfect but should not be causing this issue. The top right cylinder that seems to be contributing the most is at 115 and one of the cylinders on the left side that seems to be causing the problem is at 120. So it isn't a compression problem.

I swapped the powerpacks from left to right to see if the problem moved but it was exactly the same. The right side was still running well and the left side wasn't making much difference when unplugged.

I swapped the two coils from the left side to the right side and vice versa but still no change at all.

I'm not sure what else to try as I have ruled out fuel and compression and the way it all of a sudden finds its power and gets up to speed seems like an electrical issue to me. The powerpacks and coils have been ruled out as problems so the only part left I can think of is the stator. However, how would this cause a problem on only one side of the motor?

Any advice is appreciated.
 
Have a look at your stator and see if there is any "black goo of death" dripping from it.
Just look between the flywheel and the top of the engine.
 
You might have a problem with the reed valves on the cylinders not contributing during the RPM drop test.
Since you have covered fuel, compression, and spark - I don't think there's much else.
If the reed valves don't seal correctly, the air/fuel charge won't be delivered adequately to the affected cylinder/s.
I saw a video where a guy layed a piece of paper over the intake manifold hole where the carb bolts over, and them turned over the engine.
Says that the paper should get sucked in. If the paper gets blown off, the reed valves are not sealing.
I thought that was a neat way to check it.
Anyway, good luck with fixing the issue.
 
James in Canada said:
Have a look at your stator and see if there is any "black goo of death" dripping from it.
Just look between the flywheel and the top of the engine.
Click to expand...

I don't see any leakage from the stator. I also did the resistance and voltage checks for the stator and the timing plate in my repair manual and everything checked out.

CarMech1969 said:
You might have a problem with the reed valves on the cylinders not contributing during the RPM drop test.
Since you have covered fuel, compression, and spark - I don't think there's much else.
If the reed valves don't seal correctly, the air/fuel charge won't be delivered adequately to the affected cylinder/s.
I saw a video where a guy layed a piece of paper over the intake manifold hole where the carb bolts over, and them turned over the engine.
Says that the paper should get sucked in. If the paper gets blown off, the reed valves are not sealing.
I thought that was a neat way to check it.
Anyway, good luck with fixing the issue.
Click to expand...

I don't think it's a reed valve issue as there is no spit back from the carbs at all. I'm also not getting any of the other bad reed valve symptoms such as hard starting.


The motor starts well and stays running, it is just very rough due to the imbalance of the cylinders. I can take the two plug wires off on the left side and it will stay running alright but if I take the two plug wires off the right side it dies instantly. Could the timing on the left side somehow be out causing it to only partially run on the left side?
 
canadaboy25 said:
I don't see any leakage from the stator. I also did the resistance and voltage checks for the stator and the timing plate in my repair manual and everything checked out.

I don't think it's a reed valve issue as there is no spit back from the carbs at all. I'm also not getting any of the other bad reed valve symptoms such as hard starting.

The motor starts well and stays running, it is just very rough due to the imbalance of the cylinders. I can take the two plug wires off on the left side and it will stay running alright but if I take the two plug wires off the right side it dies instantly. Could the timing on the left side somehow be out causing it to only partially run on the left side?
Click to expand...

Well we both know that something is causing the cylinder imbalance. It's just a matter of finding it. Not usually the easiest part.
The reason why I suspected reed valves is because you have covered fuel, compression, and spark. And no matter what coils or packs or carbs you have swapped around, the issue remains with the same cylinders. So it has to be for whatever reason, those cylinders are not receiving an adequate air/fuel charge, or the spark is dropping out.
Did you not mention that you are still getting spark on the affected cylinders? The spark may not be consistent or strong enough for some reason.I went through the seemingly endless saga of trying to figure out why the '64 Evinrude 9.5 that I used to own would only run on one cylinder. But with the help of the folks on here, I finally managed to correct the issue. Anyhow, you're going to want to go back to the beginning and verify everything again. Check spark with a proper tester, make sure the carbs have zero issues, make sure your compression tester has no issues (been dinged by that one before...ha!) and see where you are at. There's clearly something you missed. You'll get it though. Sometimes it's the stupid things you don't expect is what ends up being it. Good luck.
 
Did this problem show up suddenly ?----How did it run for you last year ?----Were coils ever removed from cylinder head ?
 
CarMech1969 said:
Well we both know that something is causing the cylinder imbalance. It's just a matter of finding it. Not usually the easiest part.
The reason why I suspected reed valves is because you have covered fuel, compression, and spark. And no matter what coils or packs or carbs you have swapped around, the issue remains with the same cylinders. So it has to be for whatever reason, those cylinders are not receiving an adequate air/fuel charge, or the spark is dropping out.
Did you not mention that you are still getting spark on the affected cylinders? The spark may not be consistent or strong enough for some reason.I went through the seemingly endless saga of trying to figure out why the '64 Evinrude 9.5 that I used to own would only run on one cylinder. But with the help of the folks on here, I finally managed to correct the issue. Anyhow, you're going to want to go back to the beginning and verify everything again. Check spark with a proper tester, make sure the carbs have zero issues, make sure your compression tester has no issues (been dinged by that one before...ha!) and see where you are at. There's clearly something you missed. You'll get it though. Sometimes it's the stupid things you don't expect is what ends up being it. Good luck.
Click to expand...


Yes, you are right. I will have to go through everything again to make sure. I am extremely confident that my problem is not in the carbs themselves as I took apart and thoroughly cleaned my original ones several times which made no difference. I also put carb kits in the original carbs which made no difference. I then got two different carbs and cleaned them but the exact same problem remains. The chances of having 4 carbs that are not working properly on only the left side after multiple cleanings is very slim to none. So I think I can safely say I've ruled that out as the problem.

I will take the reed valves out and give them a visual inspection just to rule them out as a potential problem. Hopefully I can swap them from left to right to rule them out entirely.

I do have consistent spark from the plug wires when I disconnect them as I can see it forming a very bright spark of at least a half inch to the pliers I used to pull them off. I will hook up an oscilloscope to the coil inputs of the 4 cylinders so that I can verify the coils are getting a strong and consistent signal at the correct time. I know it is not the coils themselves or even the power packs as I have swapped them from left to right but the problem stays on the left side and the right side runs fine. Perhaps even though the stator and timing plate test ok during cranking they may have an issue under load. Testing with the oscilloscope while running should allow me to see what is happening in much more detail.

racerone said:
Did this problem show up suddenly ?----How did it run for you last year ?----Were coils ever removed from cylinder head ?
Click to expand...

The problem showed up quite suddenly about 5 years ago. We got a different boat so this one has sat around since then and I just got to working on it this year. Nothing was done to the motor at all when the problem started. We tried new plugs and cleaning the carbs but could not get any improvements. All the fuel lines are new and the fuel is new as well. I have different carbs that have been cleaned out on it now so basically the whole fuel system has been gone through. The problem is on both cylinders on the left side so my fuel supply to both carbs must be alright as the right side runs fine and the fuel supply in the carb bowl is shared between the two sides. So my problem has to be something either physical or electrical with the left side.
 
Remove the black/yellow wires at the power pack and test run.Caution:you willnot be able to stop motor with key switch. Choke till it dies.
 
So I'm back on this project again. Pulled the boat out and got it fired up and the same issue remained. Engine runs and idles a bit rough. Pulling both spark plug wires on the left side makes a very slight change. Reattaching the plugs gives a short burst of increased rpms, then back to where it was. It almost seems that while the wire is disconnected, the cylinder has time to fill with unburnt fuel, and then when the wire is reattached, the fuel burns quickly and revs up for a second. Pulling either spark plug wire on the right side makes a significant difference and stalls the engine if it is not on a fast idle. So clearly there is a problem with the 2 left cylinders not performing well. I can post a short video of this process to make it more clear what is happening.

I redid the compression test and got exactly the same results as I posted above. So compression is not the issue.

I have previously swapped spark plugs, coil packs, and power packs from the left to the right side of the engine and the problem has stayed with the left side of the motor. This has eliminated every single part of the ignition system except the stator and sensor coil. I have done the resistance checks on both the stator and the sensor coils and all readings are within spec in my workshop manual. No coils have shorts or leakage to ground. I also hooked up an oscilloscope to the 2 pin connector coming from the stator to the power pack. I get an AC like signal with maximum peaks of about 300V on the right side of the engine and 330V on the left side. So the left side is producing a slightly higher voltage than the right side and the problem is on the left side of the motor. Therefore, I do not believe it is an issue with not enough voltage from the stator. The sensor coil is obviously working as I get a strong consistent spark from the spark plug wires on the left side of the motor. I have removed the flywheel to inspect the coils and they all look great. No leaking black goo, no cracks, no discoloration. I think from all of these tests, I can eliminate an electrical issue.

This leaves me with fuel as my only potential issue. As previously commented in the thread, the reed valves are suspect due to the symptoms. I do not seem to be getting any noticeable spitback through the carbs. However, there was some oil pooled in the bottom of the air silencer when I removed it. I'm not sure if this is evidence of slight spitback over time, or if it is just oil left from fuel leaking out of the carbs when the motor is trimmed all the way up.

I have just removed the reed valve housing from the motor and all the reeds look perfect. None are cracked or bent or missing. If I shine a flashlight at the back side and look from the front, I can see a very small sliver of light through each reed valve, even the ones on the right side of the engine which is running properly. My shop manual says they are allowed to have a gap of 10 thousandths between the reed and the seat. My gaps are nowhere near that large. I doubt it is even 1 thousandths gap. The amount of light seeping through is comparable from the left side to the right side so I find it hard to believe that this could be making such a big difference to how the two sides of the motor run. I will try swapping the reed assemblies from left to right to rule those out as an issue, however I don't think it will make a difference since they look to be in really good shape and there are no distinct differences between the left and right sides.

I am running out of ideas of what else to check. I am extremely confident that it is not a carb problem for the reasons listed earlier in the thread. It is clearly not a compression issue. It cannot be the spark plugs, coils, or power packs since they have been swapped left to right. I have done every test I can imagine on the stator under the flywheel and cannot find any indication that it is not working correctly. This leaves me with a fuel delivery issue. I have been researching the symptoms of bad reed valves and everything that I read sounds like it was being written about this motor. Almost all of the symptoms line up except the spitback. Rough idle, poor low end power, hesitation off of idle. I just cannot see what could possibly be wrong with them as they look near perfect.

I will report back tomorrow with the results of switching the reed assemblies from left to right. I will also try to get a video of disconnecting the spark plugs so you guys can see the problem more clearly.

Any other ideas on what to check are appreciated.
 
Anybody ever figure out what's wrong with this motor ???? I agree with Racerone, pull the head.
 
Last edited:
Yes, I did manage to get it fixed. It ended up being two separate issues which is why it was so hard to troubleshoot. Sorry, I forgot to post an update.

After making new gaskets, cleaning everything, and reassembling the reed valves on the motor, I fired it up to give it another test. Now pulling any spark pug wire produces a noticeable rpm drop. There must've been an intake manifold leak somewhere that I fixed when I made new gaskets and sealed everything up. I took the boat out for a test on the lake and it seemed to be working perfect for about 20 mins and then it just lost power like 2 cylinders had died.

Due to how abruptly it died, it sure seemed like an electrical issue. So I bought 4 inline spark testers and took the boat out again with the motor cover off and a spark tester on each cylinder. I drove around all day and could not get it to act up. All cylinders had perfect spark. Finally as I was going to shore to quit, it acted up. One cylinder on the left side had no spark at all and the other one was intermittent. On the right side one cylinder was still firing well and one had intermittent spark. I swapped the coils left to right and the dead cylinder remained on the left. I then swapped the power packs and the dead cylinder switched to the right side.

I installed two new power packs and the motor has more power than I ever remembered. So the issues ended up being a leaky intake manifold causing the cylinder imbalance at idle, and two bad power packs that only acted up when they got to a certain temperature, but started working again if you managed to get the motor to top speed. Really tough to troubleshoot two problems at once with one being intermittent.

Sometime I will tear the bad power packs apart and have a go at fixing them.
 
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