2003 75 HP Mercury Problems

[Okie556]

After setting up for 3 months my engines starts and will run at fast idle but dies when idle down so I can back off trailer. Probably gummy carbs.....question is....will it help to remove air cleaners and spray carb cleaner or WD-40 into carbs while running? Or can I remove any plugs on carbs and spray cleaner in from bottom? Don't have money to take to repair shop. Thanks in advance for any help.

 

[Silvertip]

Re: 2003 75 HP Mercury Problems

Spraying anything into the carbs does nothing since it is the passages and jets inside the carb that get clogged up with crud. If you are really tight on funds and don't have the skills necessary to disassemble and clean the carbs, then one thing to try would be to add a healthy dose of SeaFoam to the fuel and "GENTLY" run a tank of fuel through the engine. Sometimes that crud can be cleaned up. If that fails, then you likely need some carb work. To avoid the problem in the future, ALWAYS add a fuel system stabilizer like SeaForm or Stabil to the fuel, then run the engine long enough to get the treated fuel into the engine before putting it to bed. Just adding stabilizer to the fuel without running the engine does nothing to protect the carbs.

 

[Okie556]

Re: 2003 75 HP Mercury Problems

Thanks for reply. Can't run much fuel through engine as I can't get off trailer. Only run at fast idle. I am fairly mechanical savy just worried about messing up the linkages and such. Haven't looked but can you remove bowl off carbs without taking carbs off engine?

 

[1nebel0]

Re: 2003 75 HP Mercury Problems

I have a 90h.p which is the same motor. Every boat I have has a racor water filter on it...You need to add a filter to one catch any water that will kill your motor as well as the filter will catch the crud....Take the carbs off, pop the bowels off and if you are lucky you won;t hurt the gaskets..The kits are cheap since they have nothing in them...I rebuild my carbs every year given the crap gas we all have today..Cheap insurance on such an expensive motor. There is almost nothing to do other than clean the jets, blow out the passages and put a new needle and seat in..You can do this with your eyes half closed....good luck

 

[Okie556]

Re: 2003 75 HP Mercury Problems

I have a 90h.p which is the same motor. Every boat I have has a racor water filter on it...You need to add a filter to one catch any water that will kill your motor as well as the filter will catch the crud....Take the carbs off, pop the bowels off and if you are lucky you won;t hurt the gaskets..The kits are cheap since they have nothing in them...I rebuild my carbs every year given the crap gas we all have today..Cheap insurance on such an expensive motor. There is almost nothing to do other than clean the jets, blow out the passages and put a new needle and seat in..You can do this with your eyes half closed....good luck

Thanks......I'll give it a try.

 

[Okie556]

Re: 2003 75 HP Mercury Problems

Okay so installed new ignition switch.....key stuck in old one and then decided to hook up water hose and try to start engine. If you'll remember at lake engine started and would run at very fast idle but would not idle in neutral so couldn't get in gear and run. Left in neutral did not go to fast idle on shifter......choked one time and it fired right up and idled great. Didn't run very long......because it was one the hose but I did kill and restart 3-times...no problems. So maybe old switch with stuck key was choking all the time or maybe this engine just prefers to be started at idle. Hopefully when I take to the lake will start again with no problems.