Test Run #1.... Fail

[DeclansDaddy]

Well after getting my 1985 Johnson 150 running like a champ in a barrel I finally got time to take it to the river to give it a test run. Again I've had this thing running in a barrel for 20 minutes at a time with no issues at all. And actually ran it on the ears for a few minutes right before I pulled out of the driveway today to take it to the ramp. Soon as I started it after we put her overboard I could tell something was wrong. It won't idle at all and if I run it up to 2000 rpm it will spit and sputter like crazy. I checked the fuel ball while it was running and it was hard the whole time. After tinkering with it for an hour we pulled it back out. I brought it home, stuck it back in the barrel and its running like a top. I'm assuming the difference in back pressure is making the difference? What would that effect? I know very little about 2 strokes, or any boat motor for that matter so any insight will help. Also I'll add that the VRO had been deleted and i put 25 gallons of fresh gas in and mixed it 50:1. Thanks in advance. A compression test was done recently and the motor had 85-95 psi on all cylinders and I've been told for these old crossovers that this is acceptable.

 

[racerone]

What is the compression today ?-----Do you have spark on all six leads ?------The ignition system full output must be tested.---Does spark jump a gap of 7/16" on all six leads ?

 

[steelespike]

I would call that barely adequate. Rule of thumb is 100 psi as the minimum.
You might try a different tester. They are known for being erratic.
A number of things could be going on.Bad crank seals,low compression, lean condition.
Raise the barrel or lower the motor to create the on water issues. n

 

[emdsapmgr]

The stock 85 150's came with the new low compression bathtub heads. 90 lbs is common on them. It should run ok with those numbers. If you have the 150S model, then the compression is low. The 773 heads on a 150S model will be in the 100 lbs range. That engine will seem to run just fine on 4 or 5 cyls when idling on the trailer. You won't be able to tell just how many cyls are firing. Another matter when the exhaust is 2' underwater. You need all 6 firing. Follow Racerone's suggestion and check for spark. Esp when it's idling- in gear when floating in the lake. (under load)

 

[DeclansDaddy]

Well did a compression test today and I'm getting 60-70psi/ cylinder. Looks like I may be looking for another motor. I really don't want to dump a couple grand in this motor. I did the test with 2 different testers and also used the regulator on my compressor to test both the testers so seems I found the problem. I pulled the plugs and 3 were covered in black gooey sludge and 3 were clean and soaking wet. Not all on one side or the other, mixed results. So I'm assuming the low compression in that deep of water the motor couldn't breath right and started fowling plugs out. I wiped the plugs off put it on the hose and it runs great.

 

[racerone]

Pull the 6 wee bypass covers and inspect pistons and rings.

 

[emdsapmgr]

Those engines do tend to accumulate carbon around the ringsets. It's normal for the crossflow family to have this problem-on a long term basis. The carbon around the ringsets will appear quicker if the engine is running cold-thermostats stuck open. You will probably find some compression increase if you do a decarb procedure on the engine. (maybe even twice.) Get a can or Bombardier Engine Tuner from your local Evinrude dealer and follow the instructions on the can. It may not restore compression completely, but it's likely to be better. Whether it's salvable at that point depends on final compression readings.

 

[DeclansDaddy]

Pull the 6 wee bypass covers and inspect pistons and rings.

Yeeeaaaa totally don't know what those are. Ultimate outboard newb here.

 

[DeclansDaddy]

Ok so I found the covers you spoke of and pulled them off and believe I found my problem. Every piston has a broke ring. They all seem to be the top ring and a couple weren't even there, the rest there in pieces. Looks like a powerhead rebuild or new (used) powerhead are in order. Can't catch a break.

 

[racerone]

Now you know , and that is a very common problem on these engines.-Look into a set of WISECO pistons.