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Discussion Starter · #1 ·
I have a 2010 Mercury Optimax 90 2 stroke and have been dealing with fuel delivery issues for what feels like forever. I have had the fuel lines replaced, swapped filters numerous times and still cannot get more than 1 good solid WOT run. Motor starts and idles with absolutely no issues, only acts up at WOT. I can run to a spot, fish or whatever and when I try to get up to WOT after leaving a spot the motor starts sputtering and bucking big time. I was told that I had water in the fuel a couple of times and the tank was drained and flushed each time. I'm wondering based on something I heard if I need to clean (or have) the fuel rails cleaned, possibly the injectors too. I have never attempted anything like this and wonder if I can do it. I'm pretty mechanically inclined and would like to save some money because this boat and college is draining me. Anyone attempt this and if so how difficult is it?
 

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I’ll leave the motor techs to answer your question... The one thing I’d suggest first is to have the fuel pickup checked if possible- and possibly have it replaced (if possible). Sounds to me like it’s picked up something that only obstructs it at highest demand.

The first step toward that end would be to get a known good portable tank with fuel line - and by-pass your existing fuel system entirely... If that clears your problem with an actual on the water test run... then it’s not a motor problem.

Hope this helps... aren’t boats fun?
 

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I am not a tech, but like you I am somewhat mechanically inclined. I removed the entire fuel delivery system from my Optimax 225 about 2 years ago. I had the injectors cleaned and flow tested. I cleaned the rails and other components myself. The compressors have a history of causing problems with these systems. Lot of good info on the web. Do your research, take a lot of good detailed pics b4 you touch anything, get a manual and read the sections that will pertain to your work b4 you start. I also floated the reed blocks and replaced the reeds while I was in there. It can be done, do your homework. You will need special sized torque wrenches for reassembly. If you have questions let me know and I will help if I can.
 
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Discussion Starter · #4 ·
Thanks for the responses.
I’ll leave the motor techs to answer your question... The one thing I’d suggest first is to have the fuel pickup checked if possible- and possibly have it replaced (if possible). Sounds to me like it’s picked up something that only obstructs it at highest demand.

The first step toward that end would be to get a known good portable tank with fuel line - and by-pass your existing fuel system entirely... If that clears your problem with an actual on the water test run... then it’s not a motor problem.

Hope this helps... aren’t boats fun?
Didn't even think about trying an external tank but I think I will try that first. I know BPS did replace a piece (can't remember the exacts right now) right near the pickup. And right now this is boat is nowhere near fun. Hopefully soon it will be again.

I am not a tech, but like you I am somewhat mechanically inclined. I removed the entire fuel delivery system from my Optimax 225 about 2 years ago. I had the injectors cleaned and flow tested. I cleaned the rails and other components myself. The compressors have a history of causing problems with these systems. Lot of good info on the web. Do your research, take a lot of good detailed pics b4 you touch anything, get a manual and read the sections that will pertain to your work b4 you start. I also floated the reed blocks and replaced the reeds while I was in there. It can be done, do your homework. You will need special sized torque wrenches for reassembly. If you have questions let me know and I will help if I can.
I've been looking up how to do this on the interweb and it looks pretty straight forward. I am going to purchase the service manual and as far as the tools go I think I am good to go, if not Harbor Freight is very close. :D
 

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Going to an external tank and different fuel delivery (everything including fuel bulb and existing connection to the motor) is actually one of the first things a well trained tech will do to rule out a bunch of possible motor troubles. If that separate fuel system doesn't clear the problem.... you've at least eliminated tank and fuel delivery to the motor as a factor - then start looking at the motor...

If that simple change does make your motor healthy again - you know it's your fuel system that's the problem.... Remember as well that some problems will never show when you're running the motor out of the water on a flush attachment... You have to be on the water - at speed, to be sure...

Aren't boats fun?
 

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Discussion Starter · #6 ·
Hooked up to the hose it works great and even at idle on the water, it's only at WOT does it rear its ugly head up. I'm going to try and get a tank today and hopefully maybe Saturday or Sunday I can test it out. Maybe even Friday after work.
 
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