I have a 1990 150 Evinrude 150 and I think I am going to take it in and get a fresh water pump and impeller. The engine runs great and has no problems starting or running. I was thinking maybe getting the carbs cleaned and gone over but the mechanic tells me that would be close to 600 dollars for the carbs. I think or I hope he may have thought that I was talking about a rebuild on the carbs. My question is would a shot of sea foam in the tank clean them or should I not do that. I dont know what sea foam would do to the oil gas mix.I dont know how much sea foam I would need to use either. Also, how often do you guys change the plugs? I am pretty sure that I can do that but I dont know anything else about these motors.
Input on thi sis greatly appreciated.
Thanks

I use a can of seafoam in every tank for preventive measure, it absolutely helps.
Once a year the motor gets a power tune treatment, you pick that up at a mercury dealer, if you've never used it before get two cans.

That year vintage motor should get plugs every year, those champions don't last long.

Ive gotten similar qoutes on having my carb'd 150 vmax serviced, it just rolled 500 hrs, and runs great. i will say that I run it no less that every 2 weeks and I credit that for its reliability.

Change your LU impeller regularly (Once a year for those who do not fish year-round and every 4-6 months for those that do) HP motors may even change every 2-3 months. It is cheap insurance to keep the water flowing!!

Carbs don't need to be cleaned unless they are dirty.

If the motor is running fine and you haven't run through any bad fuel there is no reason to clean your carbs. We sold our 1985 Evinrude 2 years ago, carbs were never opened.

Like someone else said change lower unit lube, have water pump service done maybe plugs and put an ounce of seafoam per gallon of gas and go run it. Doesn't take much to keep it running good. Sitting up with fuel in it is the worst on carbs. I would also change thermostat if they don't include it in the water pump change.

+1 on Seafoam. Every time i put gas in. 1 oz. per gallon of gas.

Cheaper alternative to seafoam is startron, I run it in every single tank I put in. Supposed to be something very similar: clean carbs, stabilize fuel, protect against water, all the good stuff. I run a can of seafoam every couple of months just because that's the tried and true stuff, been around forever cause it WORKS! +1 on impeller, lower gear unit oil, and inspect your old oil to make sure there isn't water in it! Learned that the hard way.

Change the water pump impeller and the lower unit oil. The sparlplugs and the fuel filter. Put a can of Sea Foam to 12 gallons for initial shock cleaning then use as recommended. No need to worry about carbs if everything running right.