342 fuel system

tkrfxr

Where is the anti-siphon mechanism in my 2005 342?

I had a fuel leak and need to have the mechanics check the fuel system....

The engines are Volvo 5.7 OSXi-DF.

Is there a solenoid valve or an old-fashioned ball-and-spring mechanism?

I had 10 gallons of gas removed from the stbd engine, and we are chasing the root of the problem.

Black_Diamond

Unless something is in the pickup tube, there is no anti-siphon devise in-line on my 342.

tkrfxr

According to ABYC and USCG regulations, there must be one unless the tanks are below the level of the engines....

I just don't know how to test the system....to see if the problem can be prevented in the future...

The injectors have been removed and were sent to be tested....

212rowboat

I'm curious, too.. not that it matters to me.. :-)

The fuel system is absolutely closed system, and the injectors are 'normally closed' mechanisms in themselves.. I'm willing to be the fuel pump seats, and if the boats equipped with a cool fuel system, that will do it too.. but, I'd like to know how the fuel can siphon through the filter/water separator... I'm all but certain a spin on filter/seperator is equipped with a diaphragm valve to disallow flow unless it's under pressure... It's not under pressure when the ignition is killed, because the injectors close north of the fuel filter/ cool fuel / water separator, and the pressure south of those devices will fall...

Pressure on the rail is where I'd start hunting.. it should bleed slowly once ignition is killed.. if it bleeds rapidly, a good nose will locate the trouble.. if it doesn't bleed slowly, I'd be looking at seals south- like a spin on gasket, or a bad fitting, or anywhere else the lines can rub... I'd also pressure test the tank.  

212rowboat

And by the way.. fiveomotorsports.com has rockin prices for brand new spitters.. you can drill down and find them fairly easily.. my opinion is that seimens injectors are the best around, and can be cross referenced using different attributes.. you may find buying new ones rivals reconditioning the ones you have depending on what is wrong with them...

Don't get me going on injectors.. :-)

I'll add this, though: if you're replacing one, you will be asking for issues.. replace them all, is my advice, and have them bench tested for uniform volume flow and spray characteristics at their rated pressure.. these engines can't sniff exhaust and adjust trim w/o an o2 sensor, which means the puter trims based on tables and temps... One cylinder could be running rich or lean, and you'll not know it until damage occurs.. even with a o2 sensor, it can only tell which bank (dual sensors), or overall a:f from both banks (single sensor)... You'll want them benched for uniformity.. even injectors off the line one behind the other will vary.. benching them groups them by 4's, 6's, or 8's, and gets you closer.. take a variance out of the possible issues, right?

Call up five o, and ask to speak with Bruce.. man knows his business.

tkrfxr

Thanks, drew....

I know the tanks are higher than the engines...I also have fuel filters on each tank, and then on each fuel cell...these do not have any valves of diaphragm mechanisms...they just filter the passing fuel without restriction.  

The fuel pumps have been tested and function fine.  The injectors are being bench tested....and are not cheap ($275 each)

The fuel pressure regulator screen has been removed and replaced with the Volvo-recommended e-clip, as per 2010 parts bulletin...the screens appeared pretty clean.

212rowboat

Thousand dollar question: does vp (or merc, for that matter) use fuel return lines?

Chebby does.. fomoco, too.. mopar doesn't always..

tkrfxr

I do not believe these engines return fuel to the tanks....I only see one fuel line going to the fuel pumps....no hose going back...

Black_Diamond

At least on my 2003 350 MAG MPI there is not a return fuel line.

Did the fuel leak into the engine or into the bilge?  The fuel lines from the tanks to the engines were run bad on mine, made a tight right angle turn against the hole through the firewall.  I mean pulled tight.  I reran new lines and made the 'corner' with a nice easy loop, no restriction or abrasion issues.  You might spend some time looking over fuel lines and connections.

212rowboat

didn't know about VP... Merc doesn't return... at least the ones I've bothered to look at.

I'd be willing to put money on a ruptured line, as BD is indicating... especially if you've habitually used ethanol laced fuel- it is caustic to soft lines... a matter of fact, this is the only solution short of stainless lines:


and that stuff is pretty expensive..

if you have/had a deterioration of lines from the inside out, there is usually evidence in the filter or in the injector baskets in the form of tiny rubber crumbs... if you have a rupture in a feed line, you're not going to generate pressure as easily to feed the engines, and should have felt a shimmy and shake in the engine, at least at some point along the way.  A leaking injector washing the cylinder would likely cause a misfire at least here and there, and it would certainly cause some more smoke/fumes at exhaust.  the best way to tell, though, about a rich (or lean, for that matter) cylinder is to pull the plugs and compare them to a chart.

so... how does it run? rough? smooth? hard start?

tkrfxr

The bilge had fuel in it, but was leaking from the oil cap, which I removed, only to find gasoline staring back at me...The oil dipstick marked oil all the way to the handle...that was when I knew...the engine was full of gas....

The fuel lines are perfectly laid out and secured without kinks or abrasions.  There is no fuel coming from the lines and the lines on the engine itself, including the fuel rail and pressure regulator were perfectly dry.

All the gas appeared to come from inside the engine.  When the spark plugs were removed, some cylinders had a lot of gas, some had a little gas, and some had no gas come out of the hole.  

tkrfxr

Here is how my story played out...

Several Sundays ago, Last Sunday, on Memorial Day Weekend, the first outing of the season, we took the family to the gas dock, fueled up 75 gallons, both tanks full. The trip to Lloyd Harbor was about 1 hour, cruised 25 mph at 34-3600 rpm, with strong winds about....Had to throttle up the starboard engine to get it started at the fuel dock, and also on the return trip. The return trip also showed some loss of power in starboard, and required backing off to 3200 rpm on plane, because of intermittent surging and falling off of the starboard engine when synchronizing (manual). Once at the dock, turned off engines, checked both and found normal oil and gear oil levels, connected the fresh water hose to each engine and individually flushed fresh water by running each engine for 5 minutes... all looked well... and closed up the boat until the next weekend... both engines started on the first turn of the key....Trip fuel consumption was 62 gallons (30 port, 32 stbd)...

Thursday I changed a spreader light, all looked good, the bilge pump emptied out some rain water from the previous few days, no smell of gas...

Friday afternoon, the smell of gas was noticed before entering the boat!...blowers on, shore power off, engine hatch up! Gas in the bilge!

tkrfxr

Port engine was all good.

Starboard engine...gas drip on rear of port exhaust manifold...
Throttle body, fuel rail, fuel regulator, intake manifold,,all dry...

oil dipstick...completely covered in oil to the very handle!

oil cap: open, look and fresh clear gasoline in the stbd valve cover, PCV valve disconnected, gas in the port valve cover!

THE STBD ENGINE IS FULL OF GAS~! Twin Volvo Penta 5.7 OSXi-DF

An emergency cleanup was done and about 10 gallons of gas were hand-pumped out of the engine, followed by removal of the plugs and cleanup of gushes of gas from several, but not all of the cylinders...

There is no shortage of theories around the dock....What do you think?

Black_Diamond

Wow, that's odd.  I think you would have had to have a series of problems for that to happen.  I can't see fuel siphoning and filling your engine with gas...sounds more like the fuel pump was still on and leaking injector(s) at the same time.  That's a lot of fuel to fill up a block...

I am not sure of the Volvo set up, but if the fuel pump is mechanical and the diaphram ruptured, that's a straight line for fuel to the crankcase.

212rowboat

The pick up tube rest at or near the bottom of the tank... Siphoning relies on suction at the other end being greater than surface tension of the liquid source.. this is where people eff up trying to siphon fuel, because they shove the tube too far in the tank..

Is the bottom of the tank above the engine or where the regulator is? That is what would have to happen to naturally flow...

Check your tank vents.. the only thing that makes any sense to me is if the tank built pressure due to heat and movement, and couldn't vent, creating positive pressure.... But ten gallons? That is freaking weird.. I dunno if it could build enough pressure to push ten gallons up the pickup tube, through the filter and past the regulator past a either a faulty injector or one that succumbed to pressure, and into the cylinders and crank case...

Two of those cylinders at least had open valves which could have overflowed through the intake runners into the valley and down into the crank case, and that is pretty much the only reason both the cylinders and crank case would be loaded...

How many cylinders had fuel loaded? If just one, okay, you bled your fuel system through a bad injector, and had the misfortune of that injector being atop a cylinder that had an open intake valve.. if two, same thing but the odds seriously decrease.. if all.. well.. that is just weird.. it's almost as of the fuel delivery process kept happening after ignition had ceased.. unless you had multiple things happen at once..

212rowboat

http://www.marinepartseurope.com/en/volvo-penta-explodedview-7744410-23-6572.aspx


take note of the replacement pump p/n... find a TSB that covered the new design.. if you have one prior to the redesign, you may have your explanation and a course of action.

212rowboat

OOOohhhhhhh Nelly.... talk about a can of worms!!!!!!!! :-)

friend, have fun with this... you've got 'em by the short hairs.. document document document...

http://seastriper.com/forums/showthread.php?t=8867&highlight=fuel+pump

you're going to have to register to see it... answer to random question is '****'... you'll see when you get there... :-)

this is something Al would have known about immediately if I hadn't P'd him O..

by the way- you learn something new everyday- the USCG doesn't allow gasoline fuel return lines.. it's considered 'under pressure'

Black_Diamond

Nice find Drew...It almost has to be an issue with the fuel pump..siphoning through filters, all the piping, fittings, etc.  just too difficult.

212rowboat

crap like this fascinates me for reasons unknown... :-)

re: anti-siphon valve.. I've got some fairly bad news for you.. If you bought your boat new, it's likely there.. if you bought it used, it's likely not.. they were problematic, so folks just ganked them.. they are just outside the tank, and amount to a check ball and spring T in the line... they liked to stick, so folks simply removed them to protect the pump..

anyway, all this is documented in that lengthy thread where I pointed you... by the way, Moby was a whale.. the four letters following Moby, which is also a short name for someone named Richard is the answer to the random question while registering at that site.. you'll have to register to see the thread... the bad word filter on this site wouldn't let me type it for you to see.

tkrfxr

The fuel pumps are electric and are OFF when the engine is OFF...certainly when I turned the batteries off at the end of the Sunday trip...there was no power to the engines...

So, can the fuel, draining by gravity from a higher level, through a bad anti-siphon valve, pass through a fuel cell with low and high pressure pumps, into the fuel rail, and out a presumably bad injector, into the cylinder, around the piston rings, and over a period of four days, fill the oil pan and up....until the level of fuel reaches the other cylinders, and fills the valve covers...and leaks through the oil cap and into the bilge?

The fuel pumps were tested and checked out okay.  The engine was run and one or two cylinders and injectors were misfiring...all cylinders passed compression test...the injectors were all sent for bench testing....still cooking....

The mechanics are checking the tanks to see about the type of anti-siphon valve....whether ball-spring or solenoid....they said the are going to need the services of a small monkey to get to the tank pickups  (? wherever they are on my 2005 342FV)

212rowboat

man, i just don't see the tanks leaking into the engine like that.....

for what it's worth, here is why:

to siphon, the vacuum needs to be able to produce more pressure than the SURFACE tension of the source- the surface, not the weight of the source from the bottom- if it's going to draw from the BOTTOM of the source, it needs straight up PRESSURE to do so...

the tanks basket is on top.. the feed tube drops into the tank, from the basket, and pulls from the lowest point.. if it pulled from the tank from a floor mounted sump fitting, then it could easily have filled your engine if the engine is lower than the tank, but as in gravity fed and relying on the pressure of the source itself...

in order for siphon to happen, it has to have a vacuum produce enough pressure to break the surface tension of the source and maintain it by creating a vacuum when it falls out the other side of the pipe/hose... the falling fluid creating the vacuum behind it HAS to be maintained.... there ain't no way fuel naturally fell through a filter/separator, two stages of pump, and into the engine.. ain't gonna happen.

your fuel was pumped into your engine... ten gallons? valve covers full? crank case filled to the dip stick top? ... that isn't the work of one open/faulted injector, or even four... that is the work of something pumping.

do you have someone who doesn't like you afoot?  seriously.. the only other thing that makes sense is pressure in the tank being great enough to push through- and only due to obstructed vents and some pretty serious heat...

I'll be really interested in seeing how this is diagnosed... it doesn't make sense.

Black_Diamond

Good points Drew. I agree, that fuel was pumped in..either something way off with the fuel pump/delivery system being 'on' or like you said someone playing bad games.

tkrfxr

Siphon, vacuum, surface tension, pressure, nonsense.....all you need is a continuous communication of vessels filled with the fuel and one level higher than the other, and by the law of communicating vessels, the levels will try to be equal to each other....if there is no obstruction, or even if there is a little...as long as there can be flow from the higher level vessel to the other, fuel will flow! 

That's why ABYC and USCG reg require an antisiphon valve...in case a hose leaks or the engine itself leaks....

I am going to test each tank with a hose and a bottle to see at what level the tanks are filled relative to the engines....the experiment will work only if the anti-siphon mechanism is indeed stuck OPEN.

212rowboat

you're ignoring the fact the tank feeds from the top and through a feed pipe that ends in the tanks lowest point... without vacuum drawing, or pressure pushing, that juice ain't budging... it doesn't matter if it was twenty feet below the tank or dead level- it ain't climbing that feed tube without either a vacuum drawing it or pressure pushing it.... if it were to siphon, that siphon would encounter the anti-siphon valve first, which according to what I read is a fitting near the tank in-line with a check ball and spring, which would present an obstacle great enough to match (by design) the vacuum created by the weight/displacement of the falling fluid on the other side... if it is inoperable or missing, the fuel pump isn't going to allow it to continue 'falling' freely, which is what is required to create a siphon effect... then, you have to have an inoperable/faulty fuel injector to be atop a cylinder in the intake stroke to fill the cylinder- which could happen but the odds are stacked against that.. I mean, you could win powerball three times in a row as well, but what are the odds? then, even after all that- the cylinder will have to flood to the top and overflow into the intake runner to flood the valley and crank case, and continue the happenstance until the crankcase is flooded, and overflows into the heads and fills the valve train...

so... continuous vessel... after this very unlikely roller coaster ride ten gallons of fuel took from your tank to your starboard engine, rising up of it's own accord and building enough vacuum behind it to continue the process, how do you figure the engine was filled to the valve covers?  is that source not above the suspected faulty injector atop the cylinder that just so happens to be in the intake stroke?

here is how you solve your problem- not kidding... collect surveillance tapes from the marina.. what you suggest is dang near impossible without pressure either in front or behind the fuel.

best of luck finding out what happened. 

212rowboat

I came back to see if there was a response, and reread what I posted above... I gotta be careful how I type things because it can be interpreted different ways.. I was aiming for humor, but failed to add one of those little smiley things. Please don't think I was being smart **** or snippy.... Plus, I never said what I set out to say, which is "siphoning is dependent on hydrostatic pressures being relieved by vacuum created by the fluid falling into the adjacent container, as if the fluid is actually connected... There are too many obstructions to maintain the flow at a constant through that system, and the second the constant is broken the flow at the previous volume stops.. there can be spillage, yup, due to siphoning, but the reason your antisiphon valve is located where it is, is for advantage of not spilling it into the bilge.. the engine is dang near protected by virtue of the filter/water separation in that the diaphragm in the spin on will not flip open without pressure..."

tkrfxr

The anti-siphon valve on the stbd tank is definitely open.  The mechanic said the tank definitely fed the stbd pumps by gravity when he disconnected the hose to the fuel cell.  This is not supposed to happen with a functioning valve.

There is no diaphragm on my fuel filters..or.?spin-on water fuel separators...they do not protect or require pressure to allow fuel to flow....gravity alone allows me to prime the fuel line and remove the air from the filters. 

There is more interesting info from the injector guys.  It appears that the passages for the injectors are too small to allow 10 gal of gasoline to flow over a period of 4 and one half days...

So they think the only other way for gas to flow into the engine is through a bad fuel pressure regulator, which has a small vacuum return line to the intake manifold somewhere....I know which one it is, and the theory is that a gravity fed system could conceivably fill the engine this way....

I will review the parts diagram and post a picture.....

tkrfxr

Actually, Drew, it's part #25 on the diagram you posted above.

tkrfxr

That little hose is of about 1/8" internal diameter, and connects the fuel pressure regulator to somewhere on the valve cover....I have to check on this...

...you could drain 10 gallons in 4 and 1/2 days! 

Black_Diamond

I'm still not seeing how the fuel pump and the filter are not enough of an obstruction to stop siphoning from a line 1/8 in dia?  That Volvo fuel pump expressly states the spin on filter has to be filled with gas so as not to run dry or the warranty is voided, so I doubt the fuel is gravity fed....If what you describe happened though, that's a very serious design flaw...

tkrfxr

That's the key...it is not a design problem,  but somehow fuel gets through the fuel cell passively and by gravity if the anti-siphon valve is open and if there is a second problem: an open outlet for the fuel futher downstream, like the bad fuel pressure regulator with its little hose draining to the vacuum system or valve cover or wherever it goes...

212rowboat

Regardless of what caused it... One way to keep it from happening again is to extend the fuel line up, install a 12vdc normally closed solenoid valve (brass housed marine rated) at the peak, and get rid of a stupid archaic check ball and valve anti siphon device... You're gonna get blamed for water in the fuel lines if you try to pursue it with either the maker of the valve or vovlo, I bet a dollar to your five..

That item #25 looks like it pulls vacuum signal from the intake manifold... Pulls it open when engine turns over.. still.. that is one helluvar roller coaster ride for fuel under only siphon powered motion... How much lower than the tanks is that dang engine?