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Jeff G.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4724
Experience:  42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
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2002 optimax 175 Mercury. 2 things, runs very ruff at idle

Customer Question

2002 optimax 175 Mercury.
2 things, runs very ruff at idle and constantly stalls. I just changed all the plugs
2 The "Water in Fuel" warning keeps coming on. I drained the float bowl and now need to change the filter, Any tricks to changing the filter?
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** whom am I speaking with?
All mercurys are cataloged by serial number, can I get that number please.
Your 2nd question of changing the filter is easy enough once I have that serial I can see which style you have. However, as to your first question. the running rough. If you do have water in the fuel, that will cause the engine. But if it is not water in the fuel then some testing would need to be done in order to figure out what the issue might be. Optimax's engine require quite a bit of tools to troubleshoot them. And you won't have them. That being said, what were you looking to do on the rough running issue?
Customer: replied 2 years ago.
I would lioke to fix it. Some sites suggest the fuel filter might be culpret. I can handle minor repairs on my own but you are correct I do not have specialty tools.
Any recommendation on additives or?
Expert:  Jason replied 2 years ago.
Additives don't fix these engines. There are so many things that have to be correct. Compression needs to be checked, spark needs to be checked, fuel and air pressure need to be checked, all 6 fuel inejectors need to be checked, all 6 air injectors need to be check. (which is done with the computer) It also needs to be checked for codes. If you have all of the tools, they are not to bad to work on. But if you don't have the tools, all you are doing is burning time. You can try the easy stuff like running it off of another fuel tank/fuel supply. And changing the filters. Sometimes that solves it, but sometimes it doesn't. It all depends on specificially what is wrong with the engine. Does that make sense?
Customer: replied 2 years ago.
Sure that makes sense, I will try the fuel filter first and see what happens from there. Otherwise you cannot help me it seems as I will have to take it to a professional which I am trying to avoid.
Expert:  Jason replied 2 years ago.
I can only answer the questions you ask, (within a realistical reason)that is about all I can do.
Expert:  Jeff G. replied 2 years ago.
When you change the fuel filter, it is just like an oil filter I would highly recommend getting the Mercury/Quicksilver brand, they come with a new fuel probe that goes in the bottom of the filter.
Pour the old fuel filter into a clear glass jar and see if you get any water. If so that is more than likely your problem.
Before starting the engine drain the VST, the tank next to the filter.
Using the fuel line to the engine, drain the fuel tank taking samples to check for water.
If you find much water totally drain the tank and add some Mercury/Quicksilver fuel conditioner, Quickleen. Mercury also has a high capacity fuel filter for mounting in the boat as well.

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