1986 Evinrude 150 no power under load

johntwright27

Recruit
Joined
Feb 28, 2015
Messages
1
Hey ya'll I am a college student fishing in the collegiate series and bought a boat last year. I am certainly no mechanic but have pretty good mechanical know-how, but am at a loss on this outboard. I bought a 1986 Stratos with an 150 Evinrude in good shape.... or so I thought. This thing has been to two different mechanics and nobody can figure out what is going on.

First Mechanic did this-

New powerpack
New impeller
New lower unit oil
New spark plugs
New spark plug wires
New fuel lines
New exhaust housing

They had it for three months but couldn't get it running right. I took it home and hooked up the muffs to see what it was doing. After a bunch of carb cleaner it fired up, but would POP every now and then. Sounded fine and would rev up good just popped every once and awhile. So I took it to another mechanic.

Second Mechanic did this-

Rebuilt carbs
Link and sync
New throttle cable

They had it for four months and I got tired of waiting for them to do nothing to it. Took it back home and hooked up the muffs again. Still having the popping problem. Did some research online on my own and came across an idea to check the spark plugs. I didn't think much of it since the first mechanic put new ones in but I figured I would give it a shot. Come to find out the wrong spark plugs were in. Replaced the plugs with the manual specs and boom the popping stopped! I thought I had fixed it. Took it out on the water for the first time since I bought it (which was February 2014) in September last year. More carb cleaner and the engine fired up. Idled well and revved up great. Stuck it in reverse and backed it off the trailer no problem. Then the problems started. Shifted into forward gear and the engine died. Several tries of the same problem and finally it went forward. At WOT the boat would only go roughly 5-10mph. Put it into neutral after realizing something was wrong and it died. Got it to fire back up but never could get it to go forward again, just died when it went into gear. Loaded it up and did more research. Decided it was time to do a compression test to see if there was a MAJOR problem. Did the test and I don't remember the exact numbers but all were in the mid 90s with none that was more than 5% different than the others. Figured since they were all roughly the same compression was not a problem.

Decided to rebuild the carbs myself so I could see for myself that they were done right. Took them apart and they were spotless, but rebuilt them anyways per the manual instructions. Redid the link and sync to manual specs. Drained the tank and put fresh fuel in the tank and headed to the lake. Still took a bunch of carb cleaner to start it up but it finally did. Usually when the motor is warmed up it starts right back up so I didn't think having to use the cleaner for a cold startup was a bad thing as I have heard these old Evinrudes are beasts when cold. First try it went into gear and off we went, though still only topped out at 5-10mph. Put it into neutral and it died. Took longer than usual to start up again but started up. Put it into gear and died. Never could get it to go forward again and loaded it up. Pulled all the spark plugs and found every single one of them is BLACK, I know it is a 2-stroke so some oil will be burned but I have a feeling that I am not getting enough combustion to burn off the oil and it is fouling every single spark plug.

I have searched this website and many others for countless hours and taken it to two mechanics and haven't found an answer that solves the problem I am having. Figured it was time to ask this question myself rather than find an answer to someone else's problem that usually doesn't sound exactly like the problem I am having. I know the carbs are good and the powerpack replaced what else could possibly cause this problem? Thank you in advance for any advice!
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Do a cylinder drop test on it to see if it's running on all the cylinders
 

175se

Petty Officer 1st Class
Joined
Mar 6, 2014
Messages
274
If the plugs come out that black a couple things I would check are, the primer system and the ignition switch. With the key on , push in on the key you should hear a click from the solenoid, that also helps to start the motor. If it or its components are defective it can put to much fuel to the motor causing an over rich condition. Also check the ignition switch. with the key on the purple/white wire at the primer should NOT have any voltage- it should only have voltage when key is pushed in. JMO.
 

175se

Petty Officer 1st Class
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Mar 6, 2014
Messages
274
Almost forgot, the red lever on the solenoid, should point at the bottom of the solenoid.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
I expect you've done a compression test-what are the numbers on each cyl? Follow Boobie's suggestion on post 2. Check your spark first. This engine will seem to run just fine on the trailer, when it's actually only running on 4 or 5 cyls. You can't tell by the sound. It's a different matter when the boat is floating in the lake, the exhaust is 20" underwater and it's in forward gear-then you need all 6 firing. As I read what's been replaced, there are two other ignition components which you've not mentioned replacing. The stator and timer base. If you find that spark is the issue, you can read how to test these two components at this excellent website: cdielectronics.com. CDI has specific condemning specs for cranking output voltages for both of these expensive components. Best to test first, it's worth your $ to do so.
 

jakedaawg

Rear Admiral
Joined
Jun 26, 2012
Messages
4,275
This is a VRO engine, correct? Drain a carb and see what comes out. Could be over oiling which would explain the hard starts and most of the issues. I have seen where the carb bowls are full of almost 100% oil.
 

glust

Petty Officer 2nd Class
Joined
Jan 23, 2012
Messages
141
I am wondering if compression numbers in the 90's might be your issue. You need three things for a motor to run. Fuel, spark, and compression. I think at 90 pounds you might be close to not having enough compression to start easily, and it might be the reason you have a power issue. It might need jugs and rings
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Compression numbers from 90-95 are normal for this engine with the low compresson "bathtub" heads. Some of these 150's made up for low compression by running higher timing.
 

Big Fish Billy

Petty Officer 1st Class
Joined
Dec 31, 2009
Messages
301
Also with a spark tester, check to see if your spark for each cylinder will jump 7/16". Also check timing...
 

glust

Petty Officer 2nd Class
Joined
Jan 23, 2012
Messages
141
Compression numbers from 90-95 are normal for this engine with the low compresson "bathtub" heads. Some of these 150's made up for low compression by running higher timing.

Good to know EMD.. My 82 Johnson J140tlcnb comes in a round 125 at each hole. I did have a teaching mechanic tell me once that those low compression motors are good to go if they start... They run on lower compression. Thanks
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
I bought an 85 150XP long block from the factory years ago. Had the low compression heads. Also had a tag on the front of the block, stating the timing was to be set at 30-pretty high timing. Never did use those heads, put a set of 79 235 heads on and lowered the timing.
 
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