1983 150 V6 Mercury Black Max problem

"Took boat to lake and it had

"Took boat to lake and it had been running good for years. It is mounted on Ranger 330-V. All of a sudden boat did not want to plane off and had miss in engine which appeared to be from firing. It would jump back and forth at full throttle trying to plane off and finally would. Once I got boat home I decided first to put kits in all there carbs. I live on lake so backed boat down and tried out after cleaning carbs. No change. I then decided to check compression and all cylinders are strong. I went on to change both power packs, trigger, and stator. Also changed fuel pump. No change in running. Still bogging taking off and may or may-not finally rev up. What is there left to change. Also I checked plugs with engine idling and timing light hooked to each plug and each is firing at low speed. Would rectifier play part of issue or do you have any other ideas. Thanks in advance for your help. Kenny"

"Well, at least now you have a

"Well, at least now you have a mostly new engine.

No, the rectifier won't affect the ignition like that.

Since you have replaced all the common culprits - and assuming that you didn't get a bad part - the next thing I would suspect is carbon build-up.

Could be in the ports or even the exhaust itself.

So try some 5 dollar magic in a can. Pick up a product from Merc called "Powertune" and just follow the directions on the spray.

It gets all kinds of cooties and goop out of the system for you.

If that makes a noticable difference but still does not completely correct the problem you may have to pull the powerhead and take more agressive action to clean out the exhaust."

"Buy a pair of nylon pliers fr

"Buy a pair of nylon pliers from your snap-on guy. Try pulling off a plug wire boot and see if the rpm drops off. If it does the the cylinder is firing. If it doesn't then someting is happening there. Spark at the right time, compression, and the proper air/fuel mixture = power"

Tried engine again yesterday a

Tried engine again yesterday after using Powertune. I also double checked for firing on each cylinder and it is strong. Fuel seems to spit out of the front of the carbs from mid to full trottle. ( Still not on Plane ). Could it be bad gas and can I clean exhaust without pulling powerhead? Thanks for you help.
Kenny Cobb

If gas is being spit out throu

If gas is being spit out through the carb throat that is a tell tale sign of a broken/chipped/deformed reed (which with that symptom would explain all your other issues as well).

You need to remove the carbs and pull the intake and get a look at the reed petals....