1988 150HP Mercury idles great but very sluggish coming out of the hole.

sn66

Recruit
Joined
May 7, 2013
Messages
2
Ethanol ate away liner of fuel line.

Removed all gas and trash from the tank
Replaced all fuel lines from tank to the carbs.
Pulled carbs and soaked and cleaned all 3 new kits
Rebuilt fuel pump new diaphragm.
120 to125 compression on all 6 cylinders
new plugs

I fish year around and the motor was running great and a week later it started hesitating. I have to inline filters 1 before the bulb and 1 under the callon. The filters caught a lot of the trash. I have replaced both filters twice.

Any advice would be greatly appreciated.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Re: 1988 150HP Mercury idles great but very sluggish coming out of the hole.

I guess it had a nice hole shot before the problems. Looking at what you did, I just think you didn't open your low speed jets enough. Not familiar with that engine, but I'd get access to the carbs on the water (on your trailer at the ramp, water level up half way on engine mid section to get proper cooling, with the boat still tied down) fire it up and start opening them a little at a time till you you can goose it and get your thrust like you want it. Chris 1956 uses a screw driver blade width as a fine adjustment and coarse would be 1/8 of a turn; is reasonable for me too.

I had a similar problem with my 90. Did all what you did pretty much and when I got to the carbs, I found pieces of engine hose in #1 low speed area and #3 high speed jet. Apparently this came from after the fuel filter. Low speed jet setup didn't take very long.

Mark
 

sn66

Recruit
Joined
May 7, 2013
Messages
2
Re: 1988 150HP Mercury idles great but very sluggish coming out of the hole.

I guess it had a nice hole shot before the problems. Looking at what you did, I just think you didn't open your low speed jets enough. Not familiar with that engine, but I'd get access to the carbs on the water (on your trailer at the ramp, water level up half way on engine mid section to get proper cooling, with the boat still tied down) fire it up and start opening them a little at a time till you you can goose it and get your thrust like you want it. Chris 1956 uses a screw driver blade width as a fine adjustment and coarse would be 1/8 of a turn; is reasonable for me too.

I had a similar problem with my 90. Did all what you did pretty much and when I got to the carbs, I found pieces of engine hose in #1 low speed area and #3 high speed jet. Apparently this came from after the fuel filter. Low speed jet setup didn't take very long.

Mark

Yes Mark the hole shot was fine prior to the fuel line issues. I will try what you recommended and post the results.
Thank you for your help.
 
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