I recently diagnosed and fixed a fuel system problem that might be of interest to others with 15+ year old boats. The problem started with 4 beep alarms on the 90 hp Mercury (2007) that left me dead in the water a couple times and eventually I isolated to just the starboard tank. The 4 beep alarm is supposed to indicate water in the fuel according to some people at the dock and research on the interwebs.
My next step was to take the boat out of the water and pump out the tank into jerry cans. I found some helpful advice on cbrats threads about using a cheap $20 fuel pump off Amazon to do this. However, after all the work of emptying the starboard tank and filling with fresh gas, I started the engine and in 2 minutes starting getting 4 beeps again. So the next step was to remove the tank, clean it, and remove the pickup tube. I found about half a cup of watery crud at the bottom (not surprising but also probably not enough to be the issue) and a broken rotted pickup tube. It surprised me how brittle and degraded the tube material was. You could snap the tube into pieces like it was a dry cracker. Link to a photo below.
http://www.c-brats.com/modules.php?set_ ... _photo.php
Anyhow, it concerned me enough to pull and replace the tube in the port tank as well even though I had not had any problems. And it was in the same shape, it actually cracked off inside the tank as I was jostling it out of the boat. Feels good to have clean tanks and fresh tubes installed, and there is no more 4 beep alarm.
My next step was to take the boat out of the water and pump out the tank into jerry cans. I found some helpful advice on cbrats threads about using a cheap $20 fuel pump off Amazon to do this. However, after all the work of emptying the starboard tank and filling with fresh gas, I started the engine and in 2 minutes starting getting 4 beeps again. So the next step was to remove the tank, clean it, and remove the pickup tube. I found about half a cup of watery crud at the bottom (not surprising but also probably not enough to be the issue) and a broken rotted pickup tube. It surprised me how brittle and degraded the tube material was. You could snap the tube into pieces like it was a dry cracker. Link to a photo below.
http://www.c-brats.com/modules.php?set_ ... _photo.php
Anyhow, it concerned me enough to pull and replace the tube in the port tank as well even though I had not had any problems. And it was in the same shape, it actually cracked off inside the tank as I was jostling it out of the boat. Feels good to have clean tanks and fresh tubes installed, and there is no more 4 beep alarm.