I am looking for a mechanic to work on my Mercury outboard in the Huntsville tx area. I'm on a budget so really not looking for a dealership. Thanks in advance.

What are the symptoms? If you can describe the problem, sometimes these TFF folks can help you resolve an issue....I do understand that if it is a major issue, it needs to be diagnosed my a certified mechanic and fixed right. Good luck and hope you catch some nice spawning bass this spring!

Boat started running very rough. Found that ethanol had ate up the inside of the fuel lines. I pulled mechanical fuel pump. It was pretty clean. Rebuilt it anyway with all new diaphrams and parts. Pulled vst tank. The liquid inside looked more like mud than gas. It was very nasty. Cleaned vst. Soaked and cleaned high pressure fuel pump. Now I'm just starting to get concerned about what this may have done to the inside of the motor. I don't want to keep throwing new parts at it and wasting money if the motor is ruined.

Here was a similar case with a 200 Mercury bogging down & mechanic advised this and it solved problem: The fuel is clogging up due to fuel deterioration.The Vapor Separator Tank has a plug # XXXXX on the bottom remove the plug. Check the fuel that comes out on a paper towel, if comes out brown or water the VST is full of varnish. Remove the VST disassemble clean the tank check the screen on the bottom of the fuel pump. Change the filter get a auxiliary fuel tank and a can of SeaFoam mix fuel and Sea Foam as per instructions on the can. Install VST and run this solution through the engine to clean injectors and cylinders. When running this solution run 15 minutes shut down let soak 15 minutes. Do this procedure till solution is gone. Check the fuel in the fuel tank take a sample of fuel and compare with fresh fuel. If there is any question to the quality of the fuel in the tank pump the tank and put in fresh fuel.

I'm willing to try that. I'm just worried that there may be damage to internal engine parts such as Pistons, rings, etc. I'm just scared that by running it I may do more damage than I have already done. How likely is it that there is internal damage?

Sea Foam should clean her out, but check the VST tank and drain it, fill it with fresh fuel and also change your spark plugs... Run the NGK's, BU8H, I'm also running a Bass Cat with a 98 200 Merc... I'm out of the Conroe area if you need help..

You can check your compression to get an indication of motor health. Probably fine with a fuel delivery issue.

Town & Country Marine. Hallsville Texas. Joe is the best. Not very close but he has customers from Houston and even further. Call him.903.668.2022

You can do like suggested and get a compression check and leak down test if you think there is damage. Probably not with issues you mentioned, but if you want it for peace of mind go ahead.
If you have not you need to replace all of the fuel lines, if the gas in the tank is old get rid of it, you can not put additives in it to fix it. Since you had break down in gas lines you need to trace from tank to motor making sure everything is clean. Running some sea foam should be fine for removing varnish. Once everything is clean and you know your compression you can move on. Others with more experience may have better advice.

Just an update. Injector clogged. Ran a piston hot and it is seized. Broke the rod. Not looking good.