150 mercury still bogging,

Quick recap, I have a 81 mercury 150 black max. It starts and idles fine, but if you put it in the water, and try to take off it bogs down, if you keep playing with the throttle and the trim it will finnally take off and runs perfect untill you slow back down then you do it all over again. But the last time I took it out twice out of about twelve times it took off like it should and ran great. Now whats been done to it, took it to a mech in the spring to have the carbs cleaned and redone he said that was my problem it wasnt called him back he said it was the stator I replaced it it wasnt the problem, took it back to him 100 miles, this time he said it was the prop so I bought a new prop, wasnt the problem called him back and asked if he did a link and sink when he redid the carbs he didnt. So I still thought it was still a fuel issue I bought differant carbs and put on it but it still does the same thing. Good compression good spark, new plugs new fuel lines, the guy that owned it before put all new electronics on it. Any ideas would be greatly appreaciated thanks guys.

Re: 150 mercury still bogging,

You still have not determined if you have a fuel or ignition problem with the motor.

One quick test to determine if you have a lean idle mixture causing the bog is to just 'bump' the key IN while attempting to accelerate, if the short shot of additional fuel inproves the condition it is a pretty good bet that the idle mix is too lean, if your model does not have adjustable idle mixture screws then the float height in the carbs are not perfect for your load. A heavier boat, or added full coolers can require a slightly richer idle mixture for acceleration than the same motor on a lighter boat.

If your carbs DO have adjustable idle mixture screws and the added fuel helped your acceleration, then back each screw out (CCW) the width of the bladeslot, repeat holeshot and readjust to perfection.

If the key bump does NOT inprove acceleration then you may need DVA testing of the trigger inputs to the switchboxes, you could have a broken wire breaking then making contact again as the throttle is moved, causing low power when a couple cyls fail to fire, then come on again when the contaact is made again. DVA test triggers witih the throttle cable disconnected and while moving the throttle open and closed at cranking speed. Remove the spark plugs and pull the lanyard to kill the switchboxes and help save the strain on the starter and battery. Since there is NO RETURN on electrical parts, DO NOT ASSUME ANYTHING and only order parts after you have PROVEN them bad.

My money is on the lean idle mixture.

Re: 150 mercury still bogging,

should have added that in tried it already. when I bump the choke it stalls the motor. I am at my wits end with this motor, according to the mech that kept guessing at what it needed next he checked all the switch boxes and trigger, but then again he said my stator was good untill his carb job didnt work then he said it was the stator. Thanks CharlieB

Re: 150 mercury still bogging,

Find a new mechanic that has a clue.This guy has you throwing your money away and pissing you off about the engine,when its his mis- diagnosis that is the big problem.I wonder how he rebuilt the carbs to begin with after he told you to buy a new prop and did not do the link and sync.Which may be the problem along with the poor if any idle mixture set up he maybe did.Who installed the new carbs and was the link and sync done on them?I am with Charlie on this one