95 Evinrude Intruder 150 rough and low compression

[damburg1]

I recently purchased a boat with a 1995 Evinrude 150 model E150GLEOM. I was told the boat had been in storage for a few years and the carbs were clogged. I made a low ball offer and it was accepted. Now I am wondering if I should continue trying to get this motor to work or send it in for a rebuild.

The motor is low in compression on two cylinders. The other 4 are good with 120 to 115 compression. The two low compression cylinders have 60 and 80 psi. These two are not on the same side and not opposite each other on top or bottom.. One is on the bottom and the other is in the middle so this might not be a head gasket. I had a mechanic clean/rebuild the carbs and scope the cylinders. He said that all the walls are clean and straight so that is why I am trying to bring her back.

So far I am idling seafoam and fresh fuel through her. Idle has improved but its not where is should be. There is still a lot of shaking. A slow low level rev to 2500rmp or so is rough so I dont rev but maybe once. I have been letting the boat sit and idle in the back yard (connected to the hose) for 30 to 45 minutes 3 or 4 times a week for the last couple of weeks. Things have improved. She starts right up, when cold and hot. I am wondering if I should investigate the electrical side for problems now that she has gone through about 7 gallons of fuel and a can of seafoam. The spark plugs are new NKGs.

 

[emdsapmgr]

Those carbed 60 degree V6 engines have been a winner for OMC since they first came out. Usually very reliable and good runners. Yours has rubber O-rings instead of a head gasket, so don't expect much difference if you change the O-rings, but it's cheap and may improve compression if any of the orings are damaged. Not a big expense here, other than your time. The compression on that engine (that Intruder version had higher compression heads than a normal 150) changed around 1995 or 1996. It should be in the 120+ range for the top 4 cyls and around 110+ for the bottom two. The bottom two have been re-designed that way at the factory, so that difference is engineered into the engines. That's normal. The engine may pickup compression if you run a can or two of Bombardier Engine Tuner through it. It will help to reduce carbon in the combustion chambers and around the ringsets. You will need to get a special injection hose (763644) to adapt the spray can to the Schrader valve on the choke solenoid. After a couple of applications, likely you will see the compression improve somewhat. Re-check it then decide your plans going forward. It's possible that the carbs could benefit from overhauls. If any fuel was left in the carbs when stored, it's likely dried up and the residual fuel gelatin may be restricting some of the carb passages. Sorry, you'll have to pull them completely apart to clean them. Usually it's time well spent.

 

[damburg1]

I found Bombardier Engine Tuner in a gallon can that can be added to the fuel. Would this work the same as using the injection hose? I had a mechanic clean and rebuild the carbs. They are nice and shiny inside now.

 

[emdsapmgr]

It will work. Might have to run a lot of fuel through the engine over time. I like the aerosol can, since you get a really concentrated amount when using. Takes a shorter time to make the application.

 

[damburg1]

I purchased a can of Quicksilver Power Tune at BassPro because I was there. I followed the directions to spray while running until the can is almost out and then spray until it dies. This was completed over the weekend and I was able to borrow a compression tester from a mechanic friend. The compression is as follows: Port side Top Down 90, 78, 118 Starboard Top Down 127, 131, 120. Its not exactly what I remember the boat mechanic told me but my low numbers are higher than his low numbers. We did not use the same compression tool either. So I assume I should Bombardier Tuner. I will also purchase more gas. I have run through 10 gallons already. Any encouragement to keep trying this is worth it because I am not far from finding an overhauler.