1996 Evinrude 150 intruder WOT is around 4000

[Cwash]

A while back i noticed gasoline leaking out from around all six of the carborators on my motor. The motor would still run fine once it got started, but it had become very difficult to start so i di a carb rebuild on it with new seals, floats, and pins. After this rebuild gasoline did not leak from around the carbs anymore and the engine fired right up. The problem is that when running it will only reach 4000 rpm at WOT and the top speed has dropped from around 65 to 45(the boat is an 18' stratos). The boat is stored 2 hrs away at the lake, but next week i will be going up there so would like to try and work on it then. What i need to know is things to try while there because i will probably not have internet so if you could help by giving me a list of things to try that might fix it, or help further diagnose the problem once i can upload my findings to here.

Thanks any help is greatly appreciated

 

[Blake0912]

Re: 1996 Evinrude 150 intruder WOT is around 4000

First thought that comes to mind is that you may have an air leak somewhere on the carbs. You could have tightened down the float bowl incorrectly causing the gasket not to seal correct or when you put the carbs back on the gasket between the carb and throttle body could have came loose and is not making a seal.
You can get a spray can on carb cleaner and spray around your float bowls/fuel lines going to carbs and see if the motor will react if it does you found your air leak. It should not react to the carb cleaner if all your gaskets and fuel lines are tight and right. But it will react if you spray the cleaner directly into the carb.

Also next time you have it in the water try squeezing the primer bulb when your running WOT if it increases RPM your fuel pump is most likely bad.

I would also check to make sure you are getting spark on all cylinders. Along with a compression test.

 

[Cwash]

Re: 1996 Evinrude 150 intruder WOT is around 4000

Ok thanks i will try to check for fuel line leaks and for a seal leak around the carbs. I will also check for good sparks(what would the gap need to be set at?). I dont think it is a compression problem because before i did the carb rebuild it ran "fine"(well once it was started), but it still reached a good speed and rpm at wot... So im thinking it has to be something related to the carb rebuild. Is there any kind of adjustment that could have been messed up during the carb rebuild?

 

[Blake0912]

Re: 1996 Evinrude 150 intruder WOT is around 4000

Spark should jump a 7/16th gap.

I believe all the jets on your carbs are "pre set" nothing you could mess up. But a pro would have to chime in to confirm. Did you make sure all your jets are clean and the floats set correctly ?

 

[Cwash]

Re: 1996 Evinrude 150 intruder WOT is around 4000

I am pretty sure the jets are cleaned out as i did this when i rebuilt the carb, but will probably clean them again when i am at the lake. About the floats being level I leveled the new floats with the rebuild then rechecked them when i noticed the problem and while it sound counterproductive i actually tried putting the old floats and needles back in and just leaving new gaskets that came in the rebuild kit and still no change.

 

[boobie]

Re: 1996 Evinrude 150 intruder WOT is around 4000

Do a cylinder drop test on it when running and see if it's hitting on all 6 cyl's.

 

[daselbee]

Re: 1996 Evinrude 150 intruder WOT is around 4000

^^^^Agree. I bet you have lost 1 cylinder. (For some reason).

 

[Cwash]

Re: 1996 Evinrude 150 intruder WOT is around 4000

Ok what is the best way to diagnose which cylinder is not firing? Would it be to disconnect one spark plug wire at a time and see if there is any change in the engine? If this is the best way would a difference be noticed at idle or would i need to run the boat to really see a difference?
Btw thanks for all the answers to my seeming endless questions i just want to be as informed as possible before i leave since i wont be able to ask questions once i can actually look at the motor

 

[boobie]

Re: 1996 Evinrude 150 intruder WOT is around 4000

Get an insulated electrician pliers and pull one plug wire at a time when running. If you notice a drop in power, that cyl is okay. No drop, bad cyl. You may have to do this at a higher rpm than idle.

 

[Cwash]

Re: 1996 Evinrude 150 intruder WOT is around 4000

ok thanks for all the information i will work on it next week and update when i get back.