Merc50 imploded/exploded VST float

[zuunami]

Our Mercury 50hp (2006), running great until a few weeks ago, started spewing fuel. On taking it apart, it appears that the float inside the VST has either imploded or exploded! We've ordered the parts to fix it, but wonder if anyone has any idea why this might happen? thanks! - Karen

[Byrdman]

Thankfully no fire!
Hope parts are available.

[journey on]

I'd hate to lose an engine off FT. Bragg, that's open ocean.

Whats a VST?

In ignorance, Boris

[jennykatz]

On Yamaha you have a Vapor Separator Tank
On newer Mercury they call it a Fuel Supply Module

They both do the same thing .They usually have a lift pump to pull up from the fuel tank and then there’s a high pressure pump for the fuel rail ( fuel injection) engines

So what might have happened your lift pump didn’t shut off ( there’s a. Float that can jam up ) and pressure built up cracking the plastic casing or just a very old engine with plastic FSM that cracked You might have to buy the whole FSM ?Good Luck

[zuunami]

thanks folks, we replaced the imploded float and associated parts (still $150 but better than $1k for the whole unit), and it runs great again.

Thanks Jennykatz for the possible cause, it's a mystery to us still, but will look at the lift pump as a potential cause. The motor is an original 2006 to the boat, and from the history we have, not used much. But at least all is well now

[jennykatz]

Make sure you change out your water /gas separator filter (I change mine every 50 hrs also same with your eng filer and try to use non ethanol gas Good luck

[zuunami]

Thanks, did both. No non ethanol fuel anywhere near here We use Mr. Filter when we get our gas, not sure if it helps or not, but can't hurt