'86 Evinrude 150xp problem

[kingkellogg]

Hello everyone, i have an 86 rude 150xp that i have had in the lake 4 times. The first two times it was great, ran perfect and would hit 4500 rpm easily. The last two times i have been out it has been slowly going downhill on performance. Last time i was out i could barely get on plane and would top out at 3000 rpm. I also noticed it would start sputtering at WOT. If i kept it around half throttle it would run fine. Any ideas on where to start with troubleshooting as i am new to the boating hobby. I have been running 87 octane and hear from some people that it could be a problem, i will be changing to higher octane and swapping plugs this week.

 

[boobie]

Re: '86 Evinrude 150xp problem

Check your compression and then your spark. If they're okay you may want to look into the fuel system.

 

[emdsapmgr]

Re: '86 Evinrude 150xp problem

Next time out have a buddy constantly prime the fuel hose bulb. That will force extra fuel into the carb bowls. If the engine runs fine while constantly priming that bulb, the fuel pump may be weak.

 

[kingkellogg]

Re: '86 Evinrude 150xp problem

I will be going today to get a compression gauge from auto zone. Am i correct that these will work as well? It comes with "14mm and 18mm ends to fit most spark plug openings." Also i will take the advice and have someone prime for me while underway, just hope that's not the problem!! Thanks guys

 

[kingkellogg]

Re: '86 Evinrude 150xp problem

Just finished a compression test. I got 92,91,97,90,90,90. Is that a normal outcome?

 

[emdsapmgr]

Re: '86 Evinrude 150xp problem

I had a stock 85 150XP factory replacement block. The compression on it ran between 98 and 104 lbs. Those engines did have low compression heads on them in that era. Yours may be slightly low, but I don't think it is a sign of any problem. The compression is very equal across all cyls-a very good sign. You may pickup some compression of you run a can of Bombardier Engine Tuner through the powerhead. I'd look elsewhere for the problem.

 

[Blazinmonkey]

Re: '86 Evinrude 150xp problem

when was the last time you had the carbs off to be cleaned & rebuilt?

 

[kingkellogg]

Re: '86 Evinrude 150xp problem

i have never had the carbs off. I just got it about 2 months ago and it is my first boat. I am learning the ropes on outboards right now.

 

[kingkellogg]

Re: '86 Evinrude 150xp problem

I have also not done a decarb on it yet, since i am going to get new spark plugs today i will go ahead and get the stuff to decarb as well.

 

[Blazinmonkey]

Re: '86 Evinrude 150xp problem

Top Secret File is a great place to start...

carb cleaning instructions???Johnson/Evinrude

http://forums.iboats.com/showthread.php?t=244013

also, what was your max RPM?

 

[Blazinmonkey]

Re: '86 Evinrude 150xp problem

decarb...

http://forums.iboats.com/showthread.php?p=2648076#post2648076

 

[Big Bubba]

Re: '86 Evinrude 150xp problem

Yeap, I agree, if you haven't done it yet or know when it was done, the carbs are probably well overdue for a GOOD cleaning, paying special attention to the high, low speed jets and there passageways.

 

[kingkellogg]

Re: '86 Evinrude 150xp problem

Rpms are said to be between 5000-5700 from what I get out of other posts on here. I started with 4500 but last run all I could manage was 3000. I ordered spark plugs today so decarb here I come!!! I will do it with theold plugs then install new. Thanks for the replies so far, this site is an asset for sure!!(

 

[kingkellogg]

Re: '86 Evinrude 150xp problem

Carbs will be next if this does not do the trick. 10 years of ATV mechanic always says "if it doesn't run righ t, carbs are the first thing to clean. "

 

[kingkellogg]

Re: '86 Evinrude 150xp problem

OK, things went well on the water today. I cleaned the carbs just with 1 can of carb cleaner ran through it at high rpm on water hose. I then put in new plugs yesterday as well. Today I went out and it was like a brand new machine, didnt lack any power whatsoever. Only problem i had was that upon pulling up to the ramp to load it started a constant horn from the key switch. I have read that this could be lack of fuel problem or overheating problems. Am I correct on this? I also ask because we were out on the water wakeboarding and tubing for about 6 hours and it never had a problem till we were loading up. Any thoughts on my new delimma?

 

[emdsapmgr]

Re: '86 Evinrude 150xp problem

There are two devices which will set a constant horn: An overheat on one (or both) heads, or a problem with the fuel system vacuum switch. Maybe you sucked up some dirt or a plastic bag around the water intakes as you were coming back into the ramp.

 

[kingkellogg]

Re: '86 Evinrude 150xp problem

Went out again today approx 4 hours, the boat sounded the constant horn while loading to leave again. Whats a good way to test the boat for overheating?

 

[emdsapmgr]

Re: '86 Evinrude 150xp problem

A hand-held laser temp gun. You can rent one from most auto parts stores. It will set a hot horn between 205 and 212 degrees depending on year. The horn will quit when the cyl head temps get back down to 175-still too hot for normal running. Normal is between 143 and 150-155.