1994 Echelon Fuel Issues? Hesitation

[Clifthanger]

A friend and I recently purchased a 1994 Malibu Echelon just for Slalom and Barefooting.  We both own newer Wakeboarding boats, but wanted something to ski and foot behind.  The boat was winterized and then sat for approximately 1.5-2 years.  We've done some work to it, but continue to have hesitation and what we feel are fuel issues.   We've replace the fuel separator and drained and replaced all the fuel in the tank with ethanol free fuel.  She seems to idle very well both on a flush kit and in the water.  At higher RPM's on the Flusher it runs well.  However, while under load in the water it hesitates and requires lots of throttle attention to get the boat to run.  Adding ether to the carb does provide a positive response so we believe its a fuel issue.   

It's a 5.7L , EFI Motor. However, the motor was redone in 2009 and whoever had it, clearly did some other "mods" in the process. 

First question....Does anyone know exactly what this is and its purpose?   I believe its a Fuel Vapor Separator Tank, but can't find anything anywhere about those on inboard motors.   Can/should it be cleaned?  Any useful information is appreciated.  

Second question....It Does have a mechanical fuel pump mounted on the side block under the fuel Separator.  Should that just be replaced?

Last question....Is there any chance the fuel vent on the back of the transom could be clogged? If so, any suggestion on how to check, remove and clean it would be appreciated.

 

****UPDATE***  We replaced all the plugs, removed and thoroughly clean the Vapor Separator tank and both injectors last night.  She's running FANTASTIC on the flush and under load in the water.  Maiden ski pull tomorrow at 7:15am or earlier!!  Thanks for the replies and input!!

TIA for your help and suggestions!

Edited July 2, 2020 by Clifthanger

[Eagleboy99]

Yup - that is a seperator.  Not sure why they added one.  You can rebuild them since they are still made.  The vent should not make a difference.

[Woodski]

There is also an anti siphon valve on the vent line that can get stuck shut, it is mounted on the fuel tank as a 90 degree hose fitting.  It looks like the spark arrestor is very dirty.  Mechanical pumps are pretty reliable but a fuel pressure test would make sense.

[Texan32]

EFI you say?  guessing its throttle body injection?  If so, it could be a partially clogged injector.  Or a fully clogged injector (if its a primary/secondary type setup).

Edited July 1, 2020 by Texan32

[Clifthanger]

17 hours ago, Woodski said:

There is also an anti siphon valve on the vent line that can get stuck shut, it is mounted on the fuel tank as a 90 degree hose fitting.  It looks like the spark arrestor is very dirty.  Mechanical pumps are pretty reliable but a fuel pressure test would make sense.

Not sure where the "'spark arrestor" is?  any insight is appreciated!  

[justgary]

1 hour ago, Clifthanger said:

Not sure where the "'spark arrestor" is?  any insight is appreciated!  

The "air cleaner" on a boat doesn't really filter air, it provides a flame barrier.  Use carb cleaner spray to clean it.