Merc dead-end (no return) EFI & Ethanol

[cigdaze]

Check this out. I was bullshtting with my mechanic over at Knight's Marine last night over some beers and found the problem on a friend's 33 PC Formula, port side engine.

Symptoms were rough idle, no power, smoke and soot. After an injector leak-down test pinpointed to injectors hanging up and hanging open, we found this.

This was only evident on the port side engine because on this Formula there's only one fuel tank and the bottom is in the shape of a vee - port side engine draws from low in the tank while starboard side draws from a little higher up in the tank.

This is a newer boat (2006) that has been run and fueled regularly. They're 496HO's, by the way.

 

[cigdaze]

More. First Pic shows the fuel rail end cap that Merc installs. This is their way of avoiding returning the fuel to the tank. So, it just sits up there - ethanol, water and all.

Second and third pic show a couple injectors. The closer to the dead end, the worse the injectors got.

 

[cigdaze]

First pic shows the last fuel rail port. Nice.

Second and third pics show the fuel that was drained from the rail.

 

[cigdaze]

These final pics simply show the dead-end cap and how it's removed with this little tool if you ever need to remove it to flush your system (like before winterizing, coming up soon).

 

[Ratickle]

So our boats that are plumbed with tank returns should not show evidence of this????

 

[fund razor]

Eeeeek.

 

[insanity]

I think I would be finding a way to retrofit tank returns.

 

[BUIZILLA]

in my business, I see and deal with this every day, it's really a sad testament of things gone wrong...

 

[cigdaze]

I think I would be finding a way to retrofit tank returns.

That's exactly what we're doing. This has been popping up more and more lately. We remove the end cap, modify it to accept a barbed hose fitting to allow it to return fuel back into the return loop.

If nothing else, remove the end cap and attach a hose to flush it into a jug every now and again as part of routine maintenance.

 

[cigdaze]

So our boats that are plumbed with tank returns should not show evidence of this????

In theory, that would be correct.

 

[insanity]

Roughly how many hours on the motors?

 

[MikeyFIN]

why not put a water separator and filter somwehre before and maybe even after the injectors?
Up in A Chill place called Finland we deal with the same problem except our engines freeze up too in the process if not so equipped and use plenty of antifreeze in fuel..basically more ethanol...

 

[Ratickle]

why not put a water separator and filter somwehre before and maybe even after the injectors?
Up in A Chill place called Finland we deal with the same problem except our engines freeze up too in the process if not so equipped and use plenty of antifreeze in fuel..basically more ethanol...

So you use dual fuel/water seperators????

 

[cigdaze]

Roughly how many hours on the motors?

260 hours.

 

[Airpacker]

In the auto side of things, we started seeing this when chrysler introduced returnless efi to the world. Tons of miss firing v6 and v8 mopars due to fugged injectors. Wosrt is always beside the end of the rail.

Easy fix on mercs is to un cap the rail and connect it to the sedon inlet of the seperator housing but, you need to put a pressure reg in between to keep the rails pressurized.

 

[cigdaze]

In the auto side of things, we started seeing this when chrysler introduced returnless efi to the world. Tons of miss firing v6 and v8 mopars due to fugged injectors. Wosrt is always beside the end of the rail.

Easy fix on mercs is to un cap the rail and connect it to the sedon inlet of the seperator housing but, you need to put a pressure reg in between to keep the rails pressurized.

Bingo! That's our fix for this!

 

[insanity]

In the auto side of things, we started seeing this when chrysler introduced returnless efi to the world. Tons of miss firing v6 and v8 mopars due to fugged injectors. Wosrt is always beside the end of the rail.

Easy fix on mercs is to un cap the rail and connect it to the sedon inlet of the seperator housing but, you need to put a pressure reg in between to keep the rails pressurized.

Did you mean second up above? Not being a smartass, just checking. Sounds like a pretty good work-around from having to run return lines to the tank tho.

Does the high pressure pump on the 496's work like a vehicle in that they prime when you turn the key on or do they have a Hobbs switch or the like, that is plumbed into the oil pressure system? So the hi-pressure pump doesn't run until it starts seeing oil pressure and shuts off in the case of a stall?

 

[Raylar]

CigDaz:
I am a little confused here by the pictures of the fuel rails and such. Mercruiser stopped using the older GM supplied fuel rails with plugged returns in 2004 when they went to Cool fuel III. You stated the boat is a 2006 model so how did it get 2003-early 2004 vintage 496's in it?? As an added note here, GM had a problem in the 496's (8.1L) engines starting in 2003 when more ethanol was added in a lot of states where the water in the ethanol laced fuel was rusting out the inside of the fuel rails that were made from steel with raw steel interiors. In 2004 GM started making the returnless fuel rail for the 496 (8.1L) and these newer units are plated on the inside to stop the rusting you expierenced on these earlier fuel rails.
This should not be as much of a problem and we have not seen it show up in the great number of new 496's we see at Raylar. However for those who have pre 2004 496's I would reccomend using Sta-Bils ethanol controlling additives to help slow down some of this moisture grabbing that ethanol does. Any ethanol laced gasoline left sitting for any appreciable time in a fuel system with non rustproof components will suffer these ills and all the water seperating fuel filters and flow thru won't help with the condition once the fuel stops flowing and it sits and grabs moisture from being ethonalized! Thank you oil companies and those pushy corn farmers for this cheapo way of oxygenate gasoline! Ethanol laced gasoline sucks! especially for users!

Best Regards.
Ray @ Raylar

 

[Airpacker]

Good point about sitting Ray. When I built my fuel system, I made allowances to hook shop air to the system and blow it dry for winter storage. The tanks will get a whack of stabil but any part beyond the tanks will be stored dry.

 

[cigdaze]

CigDaz:
I am a little confused here by the pictures of the fuel rails and such. Mercruiser stopped using the older GM supplied fuel rails with plugged returns in 2004 when they went to Cool fuel III. You stated the boat is a 2006 model so how did it get 2003-early 2004 vintage 496's in it??

Best Regards.
Ray @ Raylar

That's a damn fine question...but not inconceivable. Model year 2006 boat built in 2005 with a 2004 engine laying around the shop. Wouldn't be the first time.

Any ethanol laced gasoline left sitting for any appreciable time in a fuel system with non rustproof components will suffer these ills and all the water seperating fuel filters and flow thru won't help with the condition once the fuel stops flowing and it sits and grabs moisture from being ethonalized! Thank you oil companies and those pushy corn farmers for this cheapo way of oxygenate gasoline! Ethanol laced gasoline sucks! especially for users!

Best Regards.
Ray @ Raylar

Agreed.