Update: Well the tank as been pumped, all 8 of the injectors have been replaced, new fuel pump has been put in, new anti-syphon, new gas cap, new fuel line ... still doing it (all of a sudden the vacuum goes to 8 psi and engine stops working). He thinks there is something in the tank that restricts the fuel flow all of a sudden (had it out on a sea trial worked great for over an hour, coming off plane did it again). I talked to him about hooking up the other two fuel pick up tubes (there were 4 all together two stb, two port) and have them work in tandem, it would have to be something "big" to plug all three of the up (the fourth is out of commission). Any thoughts?
On your boat, how hard would it be to remove the fuel pickup fittings from the fuel tank in order to inspect the fuel tank pickup tubes and "screens" that should always be found at the end of the tubes?
If you can remove the fittings than that would give you the chance to inspect the inside of the fuel tank as well which seems to be needed as your vacuum readings are to high.
The following link is a 'How to test fuel vacuum rewritten by one of iboats many respected members
JustJason,
http://forums.iboats.com/forum/engi.../290505-how-to-testing-your-boats-fuel-system
When the vacuum goes high, As a test, be sure to open the gas cap to relieve/re-vent the fuel tank....Also be sure the fuel tank vent fitting, vent hose is not clogged, kinked or damaged and will flow air when adding some for testing.
Now what he wants to do is find out why the vacuum is so high (where the restriction is. Since it did the same thing with the remote tank (could not get above 2800 rpms under load, my guess would be some where beyond the fuel filter.
This quote from post # 16 is concerning though. It seems to read that the fuel vacuum went as high as 8 In. Hg while on the remote fuel tank/s? You may want to reconfirm the vacuum numbers, the fuel pressure numbers and the driveability of the engines while on remote fuel tanks (1 for each engine) so you know if you have a boat problem or an engine problem.
Is there an inline fuel filter mounted before the screw on type water separator fuel filter at the engine?
Did he say he found signs of water inside the sterndrive when he pulled the oil drain plug?
In some cases when first pulling the oil drain plug, clear water might pour out first before the oil should it have a big leak or you'll see white milky looking oil as it comes out with smaller leaks.
