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PostPosted: Sat Feb 18, 2023 3:10 pm 

Joined: Tue Jun 27, 2006 10:47 pm
Posts: 133
Location: Oregon, USA
1996 FOUR WINNS SUNDOWNER (specs in my signature)

Had to pull the engine for lots of work, and my very experienced mechanic noticed that the FUEL VAPOR SEPARATOR is badly corroded. Links to images below. It's fuel injected. OMC Part 3854149 is no longer made - can't find it anywhere. He discussed with other marine mechanics and all came to conclusion that we could simply BYPASS the FVS and go straight to the exhaust manifold. His only concern is vapor lock, but thinks that it won't get hot enough to cause that. It is also at the BACK of the engine, so if we are wrong we likely have to haul that thing out again.

What could go wrong?


Four Winns 1996 Sundowner 205
5.0fi/SX engine (Volvo Penta)

PostPosted: Wed Feb 22, 2023 6:04 pm 
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Joined: Thu Jun 29, 2006 10:26 pm
Posts: 5662
Location: Long Island NY
I did a bit of reading about this set up and apparently the vapor seperating tank being water cooled (why it corroded) is to cool the fuel pump, without it the pump can overheat and fail prematurely.
The only other option is to convert back to a 4 bbl carb. That’s actually not a bad plan if you plan to keep the boat long term since all the parts are in the aftermarket.
If it’s a Ford 5.0 (distributor in front) you’d need a cast iron OMC/Volvo marine Ford 4 bbl intake manifold & a Holley 4160 4 bbl carb. You might be able to use the low pressure fuel pump from your EFI system if the pressure is not too high for a carb. Volvo & OMC both used this engine with the Holley 4 bbl before switching to EFI. Carbs are much easier to deal with with old boats because the parts (carbs, fuel pumps, etc) are all available in the aftermarket. Holley carbs are very easy to get parts for.
I would:
find a cast iron 4bbl manifold, I saw one on ebay today
buy a new Holley 4160 carb that is jetted for the 5.0 Ford (Holley sells them that way)
tale a look at the port side of the block, see if there is a block plate for the mechanical fuel pump. If so that's good news because you can use a Carter marine fuel pump and get away from those trouble prone electric pumps
get a length of Sierra marine fuel line
put it all together and be free of Volvo's lousy habit of making parts for older engines NLA.

I have a Rochester Quadrajet on my engine that I've rebuilt a few times, it also has a mechanical Carter fuel pump and I have a spare Holley 4bbl as well as another brand new fuel pump in the box. While the carb may not run as well consistently as an EFI or throttle body system for repair they are light years better. Parts are available, and not crazy expensive, except the price of Holley carbs new has gone up a lot.

intake manifold:
https://www.ebay.com/itm/203571045427?h ... R46-tpXRYQ

https://www.holley.com/products/fuel_sy ... ts/0-80364


pump fittings:
https://www.crowleymarine.com/omc/oem-p ... ump-filter

while the fuel line may be NLA, these can be made up by a half way decent mechanic. just like brake lines.

Yeah it a lot of $$$ but adios to NLA nonsense, if it's any consolation Mercruiser does the same thing with making stuff NLA.

88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

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