Mercury 40hp idle issue

[Gravity dad]

Hi first time poster here. I have a 96 mercury classic 40hp 4cly oil injected outboard that will not idle. I can start her up with the fast idle lever up but once i put it all the way down the engine dies. I can put in gear if im quick to drop the idle lever and throw in gear and it runs ok.. the carburetors have been rebuilt twice, fuel pump and filters have been done along with the power pack and spark plugs. New fuel hose and fresh fuel. Any suggestions would be great? Thanks

 

[racerone]

Trouble shooting starts with a compression test.----Not a bunch of parts thrown at it.------Perhaps it just needs low speed needles turned out 1/4 turn at a time.------Post your compression numbers.

 

[tommarvin]

I just learned you can have fuel injectors on oil injected outboards around 96.This sounds like another post with a fuel problem.
It sounds like she runs, then starved for fuel at idle because something is plugged/dirty.
I would remove the carbs and make sure the idle jets are clean,new seals and gaskets and everything else. You should do it yourself to make sure everything is perfect. Remove and take the whole carb apart and clean everything,its on youtube

 

[GA_Boater]

I just learned you can have fuel injectors on oil injected outboards around 96.This sounds like another post with a fuel problem.
It sounds like she runs, then starved for fuel at idle because something is plugged/dirty.
I would remove the carbs and make sure the idle jets are clean,new seals and gaskets and everything else. You should do it yourself to make sure everything is perfect. Remove and take the whole carb apart and clean everything,its on youtube

Fuel injectors and carbs are not used at on the same motor and oil injection is not fuel injection. Even bringing up fuel injection is confusing.

Trouble shooting starts with a compression test.----Not a bunch of parts thrown at it.------Perhaps it just needs low speed needles turned out 1/4 turn at a time.------Post your compression numbers.

Agree with Racer on this one. With " I can put in gear if im quick to drop the idle lever and throw in gear and it runs ok." points to mis-adjusted needles.

Is this a new to you motor? Compression test is at the top of the list then.

Welcome aboard, Gravity dad.

 

[Gravity dad]

Thanks for the replys guys. Of course i started at the obvious and compression test is at 100 on all cylinders. The reason i changed all the above parts is because i have 4 different so called outboard mechanics look at it and tell me what needs to be changed, they each seem to have a different idea... so i did what they said to no avail. No they wont answer my calls. The needles have been ajusted but that wont seem to let it idle. This is a new motor to me. Not sure if it could be the oil injection somehow? It sounds like a fuel problem but i know its getting fuel at least to the carbs. Everything in the carbs seem good to me.. I at the point were i have done as much as i can plus several other "outboard mechanics" thinking of just taking it to the local marina service? I lt has to be something simple im guessing as it starts and runs just no idle? Im sure the marina will charge a mint

 

[racerone]

So why was all this information not in your first post ??----I have some other trouble shooting tips on these very nice running motors.---But I am afraid you will say that you or your " mechanics " have checked all these things already !!

 

[Gravity dad]

I didnt think. Please let me know, i appreciate ANY ideas.

 

[Gravity dad]

Perhaps its the reed valves? Where are they in this engine?