208 Fuel Plumbing Problem & Deck Removal

[Walkers Edge]

Untill recently the entire fuel system on my 98' 208 was factory stock and worked great untill I noticed my engine wanting to stall at a dead idle, even when warmed up. Runs perfectly above 800rpms. Always used Yamalube, RingFree & Startron/Stabil, never sits for over 2 weeks, etc etc.

I did the following:
- Cleaned filters, replaced separator, plugs, decarb. Engine ran and idled fine when unrestricted (using remote tank). Determined that something in the boats fuel system was restricting fuel flow just enough to bother the engine at idle.
- Confirmed fuel restriction after replacing the old stiff primer bulb, the new one would instantly dimple and collapse when the engine is running, but at higher RPM's it could still suck enough fuel through to keep up.

After a few hours of diagnosis and manually bypassing the various components and sections of fuel line I think I may have found some light at the end of the tunnel. The restriction is at the tank itself to my best approximation it is in the anti-siphon fitting/tank connection elbow/tank 'straw'.............

My question is; has anyone had a similiar issue with this assembly? I pulled these fittings out and the flow seems like it should be fine, no blockages, but when I bypass the assembly and run the same line directly down into the tank it runs fine, no restriction.

Look forward to hearing your thoughts......

 

[seasick]

Did you try running with the fuel filler cap unscrewed? Although it seems that have identified a bad anti-siphon vavle, just to make sure try uncapping the gas fill.

 

[Walkers Edge]

Good call, I tried that early on by removing the fuel sending unit to make sure the tank had adequate ventilation.

At 12yrs old I permanantly imploded a portable fuel tank one time in a skiff by not opening the vent after refueling, didnt learn what really happened untill after I swam the boat back a good 1/2 mile.....vivid memory.

 

[Walkers Edge]

BTW, the deck removal portion of this question was supposed to be how do you get that "removable" portion of the cockpit deck out after you take the screws out? No access to push from underneath due to bulkheads.

 

[JeffN]

Maybe just change to fitting to a barb and give that a try.

 

[Walkers Edge]

That brings up a good question, how important is the anti-siphon valve?

 

[seasick]

That brings up a good question, how important is the anti-siphon valve?

It's a USCG requirement I think

 

[JeffN]

I think there was just a post here a couple of weeks ago about the anti-siphon valve. IIRC they are a requirement for inboards but not outboards. I was not advocating removing the valve forever just figured a barb would be cheaper to buy and try although the replacement anti-siphon/barb can't be too expensive. But then again it does go on a boat so who knows. I had to replace one on my boat years ago due to a fuel flow issue.

 

[richie rich]

The valve is a good safety feature, even though it becomes a pain in the butt after 10 years or so...they're only 10-15 bucks so just change it and see...you've done the rest of the work already.

To remove the unscrewed deck, just lift an edge with a flat screwdriver and pry it up, once you have that in hand, just lift up and over and move it to the side.

 

[Walkers Edge]

I appreciate the ideas and responses,

I already purchased a new valve but managed to damage the elbow fitting through the process. Going to pick one up soon and put her back together. Hopefully this will solve my problem.

The deck plate is sealed in there tight with 5200 (best guess) a screwdriver and mini pry tool cannot break the seal without damaging gelcoat. Would something like a heat gun help?

 

[richie rich]

5200 on the deck cover......now I feel your pain.....you can normally use Boat Life type marine sealant that allows you to easily cut through the caulk. 5200 is an adhesive and dries a bit harder over time. Got to be careful on the heat gun as you may damage the surrounding material. Maybe a real small Dremel tool that can fit in the gap without damaging the sides. Either way its not going to be pretty...but a lot of work for sure.

 

[CAPT. DORADO]

I HAVE TWO ACCESS HOLES ON MY DECK SO I JUST OPEN THEM AND LIFT UP

 

[Walkers Edge]

No access ports on the 208's removable deck section.

 

[enfish]

I can't vouch for it, as I have not used this stuff, but they claim it removes cured 5200 without damaging gelcoat.

http://www.marineformula.com/uses.htm

 

[Curmudgeon]

Cut the sealant around the hatch edge with a razor knife. There is a product that will dissolve sealant, provided you have several months to deal with it.

Be sure to clean off all the old sealant before re-installing. I used GE Silicone II, just as Grady does (I guess that's still a good thing). Did it 1.5 years ago and it still looks good and works as designed ... :wink:

 

[Walkers Edge]

As a followup....
I basically replaced everything between the tank and the motor.

In replacing the anti-siphon valve I found some interesting details that definitely contributed to my issue.

The factory 3/8" ID anti-siphon valve only allows 1/4" of actual ID opening for fuel to travel and has the little check ball to resist flow even further. Yes, this should be plenty of fuel flow for my outboard under ideal circumstances but as age does to everything else on board the slight degredation was enough to restrict my fuel flow.

I replaced the valve with a 3/8 brass barb fitting as suggested on this forum and tested it this past weekend, engine runs like new, doesn't lose back pressure during stops, idles perfect.

Next Week: hull Compound & Wax

 

[wireline]

Just changed the tank in my 19 toumnament, had similar issues but much worse , I had leaks & after 20 yrs corosian finaly won. Use sharp razor blades to cut thru 5200 , use flat razor scraper to take off the rest then clean with acetone. Some one on this site gave me the great idea of before re-caulking put some mono in the cavity around the perimiter leave both ends out in rear for future removal. I used 60lb test should cut right thru silicone next time.