1995 40HP Johnson Problem

[dominicd]

I recently purchased a 1995 40HP Johnson J40ELE0D. Seller said it had extremely low hours but hadn't been used on a boat in many years. It started, ran, and shifted fine with the muffs on. Compression is 150 in both cylinders. Spark tested fine and jumped gap fine. Water pump was working great. I changed lower unit oil and plugs when I bought it.

The first time I took it out I started out with low throttle slowly increasing to full throttle. I was extremely happy for the first 2 minutes using it. We were going a full throttle pretty fast and I lowered the throttle way down to tell my dad something and when I went to throttle back up to full speed the power was extremely diminished. I would say it went from a 40hp to an 8hp at best. The gas used was brand new. I tried squeezing the gas tank primer bulb while we were driving but it didn't help. It still ran for the four days I was on vacation but never regained any power, in fact it may have lost slightly more if anything. It also still started fine but would die at very low idle occasionally. In neutral it revs up fine all the way up to full throttle but when in forward gear it has to power. The reverse gear did not seem to have a problem but I didn't test it before the problem started so I can't be sure.

After bring it home I rechecked the compression and it was still the same.Spark was still good too. The upper spark plug had some black on it and also had a very small amount of extremely fine aluminum shavings/flakes on it. It had maybe 2 or three small flakes a little smaller than a pepper flake and the rest was like aluminum dust. It was a very small amount, I was barely able to see it.

One more thing to mention. While we were on our vacation one of the guys who knows a little about motors messed with it a little. He had the motor in neutral and was spraying starter fluid in the carbs. He eventually worked it up to full throttle while in neutral while occasionally spraying in the carbs. But my point is it was in neutral and at full throttle for a good 2 minutes. I thought it was going to blow it was so loud with the carbs exposed. It didn't seem good for the motor. But anyway it didn't seem to help or hurt the performance.

Any help would be appreciated.

The boat is an Alumacraft AW 1860 MV

Thanks

 

[JoshKeller]

metal shavings on the spark plug indicate its time to pull the head and investigate. you didnt happen to use old gas did you?

 

[SumDumGuy]

the gas probably wasn't old, but every bit of lube was probably removed with the starting fluid.

 

[Stumpalump]

SumDumGuy » 23 Jul 2014, 22:13[/url]"]the gas probably wasn't old, but every bit of lube was probably removed with the starting fluid.

That explained the metal flakes. If it needed that much starting fluid then it's time for a carb cleaning and time to throw the starting fluid away. Hopefully it is not hurt too bad.

 

[dominicd]

Thanks for the info. The gas was brand new. I am pretty handy with fixing stuff but have never worked on engines. Do you think a carb cleaning is something I could do myself or should I have a pro do it?

To clarify, he only used the starting fluid in an attempt to clean the carbs. There was never any problem with the motor starting.

Do the aluminum shavings indicate a definite problem, or could the engine still be fine? The compression wa exactly the same before and after the problem occurred.

Thanks

 

[PatinIdaho]

Don't ever run a 2stroke with starting fluid. It washes all the oil out of it I believe.

Would think its OK as long as you use properly mixed fuel from now on

 

[dominicd]

Here is a pic of one of the new plugs I put in after three days of use, maybe 3 hrs of run time. There was a tiny bit of thick black gunk in the corners where the ground electrode meets the threads. The metal flakes were mixed in with the black gunk.

Is there any way to tell if the carbs need cleaning or do you just do it and see if it worked? I watched a few videos and it doesn't seem too difficult. I would just be worried about torque specs and screw adjustments.

 

[JoshKeller]

easiest way to tell if a carb needs cleaned with a multi carb motor is to pull the air box silencer to access both carbs. get some fuel/oil mix in a spray bottle and spray into each carb and see if the motor picks up. if the motor dies off, that carb is supplying fuel. if it picks up, its not supplying fuel. with two people in the boat, you can do this trick carefully even at wot and see which carb is the offender.

 

[dominicd]

Thanks a lot, ill try that next time out.

 

[dominicd]

Had my uncles friend look at it. He opened it up and said the carbs were dirty. One was really bad he said. Charged $130 to clean then which I though was a good deal. Wont know for sure if its fixed until I can try it out on the lake. He did say he can tell from how it sounds that its running much better and starts right up like nothing.

Thanks to those who commented and offered suggestions.