60 hp 2001 mercury big foot

[frankbh]

I have this motor on a friend's pontoon boat. If you accelerate quickly, it will stall. If you coax it up, it will advance and run. There's a bit of surging at top speed. I've cleaned, rebuilt and synced the carbs. Also new plugs. Also, what is the starting point for the mixture needles? I started at two turns out, and wound up about one and a half turns. I adjust by ear. Is there another way? Right after the carb rebuild, this spring, it ran good. Almost no hesitation on acceleration at all. When I took it out a few days ago, it's back to where I began. The fuel pump showed three psi while in the driveway, on the water hose. Ever hear of a fuel pump, or ignition coils causing this. In the spring, I swapped the upper and lower coils, and it seemed to run worse, in the driveway.

Any ideas? I appreciate any help that you can offer. BTW, I also changed the fuel hose to the pump.​

 

[Silvertip]

Two strokes need to be a tad rich when going full throttle from idle. Try turning the mixture screws out 1/4 turn and try again. Just keep track of the adjustments so you can put it back.

 

[tommarvin]

Quote," right after the carb rebuild this spring she ran good."
How long has it been since the last time she ran good.?
You need to add stabill 360 marine with vapor technolgy every time you add gas, dont add more gas than you are going to use that day always drain the gas out of your carbs when you get home.
Better clean the carbs again, install a fuel watter seperator between the tank and the motor yamaha mar-mini good to 115 hp, stops alot of BS.
Check the on motor fuel filter,
You can take the outlet side off the fuel pump turn her over and gas will gush out everywhere i dought its the fuel pump.

 

[frankbh]

This motor is a four stroke.
The owner used it throughout the summer. I assume it ran well.

 

[tommarvin]

A four stroke with carbs is still carbs, the point carbs suck.
You need to remove the welch plug and clean the idle air and idle gas openings and lines.
Remove the carbs and clean them like all the you tube videos, new gaskets if you trash a gasket no air leaks.

 

[frankbh]

Looks like I got it. I meticulously cleaned the carbs and put them in the ultrasonic cleaner again. Put it back together and set up the carbs and she ran well. Thanks for the advice.