1994 Johnson 150 Ocean pro low range rpms rough

deviljohn

Seaman Apprentice
Joined
May 2, 2008
Messages
38
Here's the scenario:

94 150 Ocean pro V6 Optical ignition, rebuilt powerhead last march..low hrs since.

I purchased this motor from a rebuilder OMC veteran, motor sat on it's side for 2 months in my shop until I got the boat ready for mounting.

Oil injection on VRO is disabled.

compression is 105-99 psi all cyls

what I have done:

rebuilt carbs w/ new kits
new used fuel pump w/ new diaphragms
removed plunger from VRO side

symptoms: at first motor had bad cough at idle, suspecting fuel issue, did the above, discovered fuel pump appeared to be sucking air, think at the bushing in intermediate housing of fuel pump (I put clear tubing on inlet and outlets to observe)

motor is running well enough now, but still has that slight annoying cough and runs rough between idle and about 2000 rpm...once motor gets above around 2000 rpms, runs fine, purrs, accelerates well etc....

so, my logic tells me (as well a guy I bought from) I may have a lean carb w/ fouled low speed jet or passageway...I am also wondering about the possiblity of a slightly fouled reed valve. Have considered putting boysens in....unfortunately, the guy who rebuilt this engine is not available to diagnose.

Questions:

1) what is best way to soak carbs for a recleaning?? Gallon can screener carb solution such as found at auto store?? or is there danger to the plastic parts??

2) How do yall feel about Boysen reeds?? I have heard they will increase power and fuel efficiency but have never installed them on a motor.

3) I also noticed that I have black spark leads with "autolite" written on them...should I spend the $$$ for OEM OMC leads I have read that the grey leads are the only ones to install for this motor....and, is it possible to have a weak spark in the lower rpm range as in failing stator, coils or powerpack??

Thanks in advance
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: 1994 Johnson 150 Ocean pro low range rpms rough

The main thing is to have the carbs totally apart with all jets out. A spray can of carb cleaner, and compressed air to blow them out will work fine. Boysen reeds' can be a very good addition when you get the engine running correctly. You cannot use automotive carbon core plug wires, if that is what you have.
 
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