Fuel Vent & Water

[Jason2tpa]

This is the first Im hearing of fuel filter water alarm. Is this alarm system installed on just HPDI models?

Obviously it's tied into the ignition wiring since he's getting the alarm with the key turned to ON position.

[pstephens46]

I have seen these vents on various boats in the past. Is there ever a time where they vent fuel versus vapor? Why are they mounted on the outside of hull?

[2stroker79]

Will not start up and run; however, during our removal of water from fuel water separator and one of fuel filter once we started pushing fuel from the tank it started to putter a couple of times when trying to fire it up. I just had every fuel filter on the engine replaced and fuel tank douched and cleaned back in October. I am hoping I don't have to replace them all again.

[pstephens46]

This is the first Im hearing of fuel filter water alarm. Is this alarm system installed on just HPDI models?

Obviously it's tied into the ignition wiring since he's getting the alarm with the key turned to ON position.

Sensor on bottom of the bowl on the engine mounted fuel filter. Is has a harness attached to it. I do not have one. A replacement cup/bowl for my boat is about $12. A replacement for the sensor equipped model is about $100. But it is pretty nifty!

[pstephens46]

Will not start up and run; however, during our removal of water from fuel water separator and one of fuel filter once we started pushing fuel from the tank it started to putter a couple of times when trying to fire it up. I just had every fuel filter on the engine replaced and fuel tank douched and cleaned back in October. I am hoping I don't have to replace them all again.

Don't know about the douching. Clearly you have water deeper that the filters could prevent. Get the source fixed and douche a bit more and you should be fine.

[2stroker79]

A week ago, Central Marine emptied the tank, changed the fuel water separator, removed the water and put the clean fuel back in the boat. I believe the 90 degree "J" type tube pointed down and water coming out of the vent line was the culprit. We did not have this problem until my Dad changed out the vent to a different model not knowing pointing down could get water in the fuel tank. As Dad stated, a costly mistake. When the Svc Mgr calls me with their diagnosis I will post for all.

[pstephens46]

Maybe Dad will foot the bill?

[2stroker79]

He will and already hating life. Its $260 service fee. It shouldn't be as much the fuel water separator is brand new from last weeks service visit. I will probably ask them to check the VST filter and fuel strainer above the VST.

[99yam40]

It was my understanding that water in fuel alarm sounds only when the motor is in neutral, and does not limit RPM.

may just had too much water to run properly
maybe I am way off track on this , but I am sure Boscoe or Rodbolt will line me out

[Jason2tpa]

It was my understanding that water in fuel alarm sounds only when the motor is in neutral, and does not limit RPM.

may just had too much water to run properly
maybe I am way off track on this , but I am sure Boscoe or Rodbolt will line me out

Since his low oil and high heat alarms were not activated, yet the engine went into rpm limit mode, this alarm must limit rpms when activated. What else would be causing engine to limit rpms? But of course, I just learned of this fuel/water alarm system this evening.

But speaking of the engine limp mode...99yam....could you detail for me HOW the engine goes into this limp mode. I understand WHY (alarm). I'd like to learn HOW. Like the actual electrical and mechanical processes that occur, if you doubt mind please.

[99yam40]

Did you read what I wrote?

ECU looks at all of the inputs and decides when to do it.
I take it it will cut the injectors on some cylinders or random untill the RPM is where it wants it to be.
I am not the one to answer this question with any proper knowledge

But as I said maybe just too much water in system for motor to run properly not RPM limiting

[Jason2tpa]

I have seen these vents on various boats in the past. Is there ever a time where they vent fuel versus vapor? Why are they mounted on the outside of hull?

I have the same vent as the new one he bought and has pictured here, as well as the same vent location. I can't speak to the fuel cap location on his vessel, but mine is located about 1ft forward of the vent, mounted flush on the rail. My hull is also 40 yrs old, so i figure this was the location they mounted vents in those days.

The vent will allow fuel to escape if you overfill the tank. Ive become accustomed to listening to the whistling sound of vapor escaping as im filling. As the tank approaches full, the pitch of the sound changes, which is when i back off the fuel lever.

[99yam40]

I have seen trailered boat being filled at gas station and liquid fuel shoot out all over someone standing in the wrong place before

[Jason2tpa]

I have seen trailered boat being filled at gas station and liquid fuel shoot out all over someone standing in the wrong place before

That was probably me, filling the tank of my boat for the first time, not knowing how much fuel was already in the tank due to a non-functional fuel sender. I didn't know the whistling sound back then. But I learned quickly after being sprayed once.

[DennisG01]

I have seen these vents on various boats in the past. Is there ever a time where they vent fuel versus vapor? Why are they mounted on the outside of hull?

All boats have some type of vent setup.

Ditto to what the others have said about fuel shooting out. Fuel will backup much quicker through a 5/8" vent hose than the 1-1/2" fill hose. I would also imagine there's something illegal (CG safety) about fuel vapor/liquid being pumped back into the boat. Newer style fills/vents have the vent built into the fuel fill fitting (an all-in-one thing). Even newer ones have vapor "catchers" (EPA requirements).