Fuel Delivery Issues

[daniel123]

Just back from a frigid, windy Spring Break week down Capt Matt's way boating/fishing/being blown around Pine Island Sound with the wife and teenager aboard the new-to-us 1998 Osprey 20 we bought and rigged, pretty much for this annual trip. The boat was great; the 1998 Johnson 115 was too, until the next-to- last day after we topped-off the 45-gallon fuel tank with 17 gals of fresh gas, to replace that we'd burned from the 45 gallons of 93 octane we had topped it off with and treated last October for the off-season. Anyway, after crossing the roughest water of the trip a week ago today, which may be a key, the engine began bogging down while on plane and eventually stopped dead. I checked the primer ball and it was sucked flat. After working it back into shape, I found we could go to about 2300 rpm before the engine bogged and we'd have to throttle back to 2100 rpm or so, which was the fastest we could proceed (8 mph) for the (thankfully short) balance of the trip. Everything points to a fuel delivery problem, since we could go slow just fine, but that's the most I can make of the problem.

Back on the mainland for the 18-hour tow back to Ohio, I removed the yellow plastic see-though bowl on the smallish (probably original) fuel filter located behind the inspection plate on the starboard wall back near the transom, and it had some black, sand-like grains on the bottom of the bowl. Not a lot, but like a couple shakes of a salt shaker would produce. I figure we had burned 20-25 gallons total by then, 17 from the older gas and the balance from the new mix. Otherwise, the small brown, cone-shaped filter appears to be fine, but I haven't looked at it closely. (nor can I find a replacement, at WM anyway, so I hesitate to remove and possibly damage it doing so)

I am assuming the fuels lines are original -- as is most of the boat, which did sit for three years before we bought it in Cleveland after the PO towed it up from Ft Lauderdale and wrapped it tight and there it sat. I topped off the tank and took the boat out a few times last season and never had a hesitation, burning through at least half a tank of his old gas/my new gas mix. Then I topped it off, treated it and put it away until our trip.

I had a new fuel sender installed last fall (which registers full all the time on the fuel gauge on the salvaged-but-as-new dash panel I had installed at the same time; is that just an errant ground?).

I suspect that:

-Maybe there is some gunk on the bottom of the tank that got worked free as we pounded through the waves and is partially clogging the pickup? We were in some rough stuff on Lake Erie last season though, which I would think might have worked any grunge loose. But if that's the case, and there is sludge in my fuel tank that 's clogging the intake, does that mean it needs drained and a cleaning is due? If so, what does that entail?

-Those original fuel lines are degrading from the inside from ethanol, and the black 'sand' is minute chunks of rubber -- which may be fouling the carb, filter, or something else?

-The primer ball is failing?

-The anti-siphon valve is clogged or was installed wrong by the marine 'mechanic' who installed (and may have forgotten or incorrectly installed the ground) the new fuel sender? I had not used the boat since that work was done, but again, when I did, if flawlessly burned 17 gallons of fuel before the problem occurred.

As always, I welcome -- and appreciate -- any and all opinions and advice.

Thanks guys.

[Blue Agave]

I'd start by checking the fuel vent.

[fitz73222]

Hi Daniel,
Try running the boat with the gas cap removed or very loose to eliminate a poor venting issue or not. If it bogs with gas cap removed its not a venting issue. If it runs well you have a vent issue.

I have seen some fuel pick ups with screens on them but most pick ups are just an open tube that ends about a 1/2 from the bottom of the tank. Remove the fuel line where it enters your fuel filter mounted on the transom and blow through the fuel line back to the tank and see if its restricted. You should hear or feel the bubbles back in the tank if it is clear.

Replace the fuel filter/water separater.
If you're seeing fuel line breakdown from ethanol, replace the entire fuel line from the main tank to the engine. You could have a piece of fuel line innard lodged on the inlet side of the primer bulb. Take off the primer bulb and look. If your bulb is going flat its obviously not an engine problem. I once had a Mercury fuel line completely crystallize internally from ethanol and jamb 2 feet of fuel line with broken pieces of greenish urethane shards; quite fascinating actually.
Run it and give us a report back.

[daniel123]

Thanks, guys. Will cq both and let you know. That cap-removed-to-check-vent-problem-trick is a good one!

Dan

[daniel123]

I just went out and removed the screw-on, white-plastic filter-cap covering the fuel tank/filler vent on the outside of the hull right under the filler. I blew into it, and thought I noted a slight hesitation of an obstruction, and then heard what sounded like fuel running/draining for a few seconds. I blew again and didn't feel any restriction and noted no follow-up draining sound. Think that might have done it? If so, what the heck could it have been and how could it have happened all of a sudden?

[Blue Agave]

How does the vent look?  Is it corroded?  Sometimes the screen gets corroded and prevents air flow. You could have blow the screen through the vent hose. Run it with the cap off as Fitz suggested and if it runs fine replace the vent.

[CTsalt12]

I bet your fuel line is deteriorating.  Had a few buddies with this issue.

[daniel123]

There is no 'screen' on the vent; what's there to keep small stuff out are slits in white-plastic knob that twists off to reveal the vent opening itself, so it's not corroded, so to speak. Should there be a metal screen of some sort under that cap, in addition to the slitted cover knob? When I blow into that vent tube, where does the pressure go - right down into the tank or into the fuel fill line?

Since all that's there now is a small fuel filter, I realize I need to install a combo canister-type fuel separator/filter in the line from the tank to the engine, which I need to replace too. Is there a preferred brand of filter/separator, or for that matter, alcohol-resistant fuel line, I should use? As for the filter/cannister, I worry a bit that I may not have much clearance behind that deck plate tween the liner and the outer hull to fit a full-size one, but I notice that Shoreline makes some lower profile/diameter ones. I also noted that they are sold at Wal-Mart, which begs the question: Are they any good?  

Thanks for all the advice, guys. Keep it coming, please!

[kaptainkoz]

I would definitely check the anti siphon valve. I had one make the motor do the same thing when it clogged up

[seabob4]

Keep in mind, anti-siphon valves in the fuel pick-up barb are only required on I/Os and I/Bs.  Get rid of it (damn, must be 3 or more years ago on Skoot's boat) and install a barb without the anti-siphon check valve.  That's one place to start...

[daniel123]

I can try to check it, but the square brass fitting on my tank (one of two; its twin is plugged) sure doesn't look like it could house an AS valve and I hate to remove that fitting and not be able to get it back on with a good seal. Mine connects to an aluminum fitting with a manual shut-off lever (I went out and shot and then tried to include a photo but can't resize the shots to dimensions that this system will accept) that then connects to the hose going to the Racor fuel filter then to the motor. Were AS valves standard on 1998 Ospreys?

Dan

[daniel123]

I'll try one more photo sizing to show my pick-up....

Nope, still didn't work. The smallest I can make my photos are 640 pix wide by 480 huigh, and whenever I try to upload them here I get the above warning in red that reads "the image must be at least 0 pix wide, 0 pix high and at most 1100 pix wide and 100 pixels high." The smallest of my resize options when I email my photos to myself to be able to resize still has it at 480 high. Damn.

[seabob4]

Daniel,
The anti-siphon is simply a SS ball held in place by a spring inside the fuel pickup barb.  It's not a valve you can turn on or off like we would think.  The spring becomes weak over time and won't allow the fuel pump suction to pull the ball away from it's seat and allow fuel to flow.

West Marine (Worst, is you know the routine!) sells straight barbs (no anti-siphon) by Sierra for $4...

[daniel123]

I'm trying one more time on showing you guys my fuel pick-up pix. I found a way to reduce it to 99 pix high...

[daniel123]

There it is! So you can see why I can't figure there's a valve in the brass fixture, right? And you can see the other fixture with the manual lever I talked about, which I realize is a fuel shutoff, and different than and AS valve. Should I still consider pulling the brass fitting and seeing if it had the spring-loaded ball inside? If I do, will that also allow me to pull up the intake hose and see if it's clogged? I'm headed to Worst Marine tomorrow, and can look for that no-AS fitting if you think that's what I need and they have 'em in stock here in OH-IO. Our is is a very small WM...