Carb Overflows

[67c&ccorv]

To test the floats for leakage;

...immerse the floats in a pan of water that has been heated 50 or 60 degrees greater than room temperature - a little hotter than you can stand to put your hand in.

Make sure there is approximately 3 or 4 inches of water covering the floats - within a few moments the hot water will have expanded the air in the floats and if there is a tell tale stream of tiny bubbles coming from the float(s) then you know the float is leaking and needs to be replaced.

You can thank mama Baush and Lomb for that trade secret.

[Al Schober]

Yeah, I'm cautious about gas too. But just when you think you have a handle on things, the bottom drops out.
The cup doesn't seem to have been approved for gasoline (even though I may have picked it up at the Officers Club at the CG Academy).

[BunnyPlanet169]

With epoxy, sometimes they almost catch fire...

[sastanley]

Al, I have had good luck with Gatorade bottles, and the single serve OJ bottles...they seem to hold gas just fine. The OJ bottles have a large diameter cap to get enough torque for a good seal for my arthritic hands too. Even though it is expensive to buy OJ in 12 oz. containers, it is convenient for a weekend cruise, so I rinse out the empties and keep a couple in the lazarette for just such an occasion.

[67c&ccorv]

UL listed for marine inboard gasoline use? That would require a manual override, and it passes the 2.5 minute flame test. Just curiously cautious....

I have one - but it didn't cost $13.00...and it is rated for use with gasoline - there is a photo of it somewhere on the MM site.

[lhbradley]

Carb leakage

I'm having some leakage issues with my card as well. However, in my case, it seems to be from the L-fitting for the scavenger tube, where it connects to the air intake part of the card. I have the carb here at home, and will take that piece apart shortly. The real question, however, is WHY is there fuel in the air intake part? I had thought the problem only occurred after filling the tank, and so I shut off the fuel valve on the tank. But when I went down o the boat after a week, there was gas. (I had put a small aluminum baking pan with some paper towel in it under the card to catch any leaks).

Thoughts?

[Dave Neptune]

No drips

Ihbradey, once the fuel enters the carb to only way for it to leak is via the needle and seat.
Often after shutting down after a few minutes of idling it is not uncommon for some fuel do "drop/fall back down into the carb from the manifold" due to the updraft configuration. AND the low spot in the carb throat is where it gathers and the scavange tube ties in. Be sure the tubing is clear into the manifold so it is functioning and there should be no leaks from the scavange tube fittings. The scavange tube is standard 1/8" copper tubing, easily available!!!

Dave Neptune

[JOHN COOKSON]

I had thought the problem only occurred after filling the tank, and so I shut off the fuel valve on the tank. But when I went down o the boat after a week, there was gas.

Ditto
After I top off the tank I get some sort of siphon or something that passes fuel into the carb. The boat reeks of fuel next time I come down to it.
I've found that if I turn off the fuel at the tank and fast idle for ~15-20 seconds before I shut down the problem goes away.
This work around does not address the root cause of the problem. I've never been able to figure out the real cause.
I think this all ties in with Al's sometimes leaky carb.

TRUE GRIT

[Al Schober]

Got down to the boat today (delayed by rain, other jobs) and installed the pressure gauge and the solenoid valve. No glitches with the installation (just one dropped nut somewhere in the bilge).
On startup, the engine was a bit hesitant and needed more choke than usual, but seemed to settle down. Fuel pressure about 3.3 psi on the gauge. Engine wasn't happy with the choke off, but ran fine with the choke pulled. Cycled the needle on the adjustable main jet (ran it in counting 1 1/2 turns, out 4 turns, in to seat, out 1 1/2 turns) and the engine now runs fine with no choke. Ran about 10 minutes and the bottom of the carb remained dry. Shut the engine off (leaving the fuel valve on at the tank) and checked after 10 minutes - bottom of carb still dry.
Would have waited longer, but a friend wanted me to sail for a couple of hours on his boat. I was considering declining but he had a young female along who I felt needed a chaperone. Catalina 42 is not my favorite boat to sail (particularly short handed in 20 knots of breeze) but we had a good time - and I only lost a little skin off one finger trying to free a hung-up jib sheet. I consider myself lucky the damage wasn't worse.
Sorry, no photos today - didn't have the camera. I'll get some soon with the remote OPSS, the fuel pressure gauge, and the solenoid valve.

[Dave Neptune]

Safety FWIW

The carb and the scavange tube should not leak!! A shut off valve is to protect the boat and you IF the carb leaks NOT TO KEEP THE CARB FROM LEAKING.

Al either your N&S has a nick or imperfection and/or the floats are way to high!

I have found that on every late model A-4 carb that I have done for myself and others that about a 1/16" LOWER fuel level seems to work better overall.

Dave Neptune

[Al Schober]

Got some photos today (engine porn) - know you like photos.
First shows the solenoid valve in the Racor inlet. Second shows the OP sender removed from the block and the Home Depot grease gun extension line installed. Third shows the OP sender and OP safety switch installed at the other end of the extension line. Finally the fuel pressure gauge on the carb inlet (and the new Facet fuel pump).
After running the engine for 15 minutes, it died. Zero fuel pressure. The solenoid valve failed to open. Removed and reinstalled barb & engine restarted. Now using manual shutoff valve. Continuity test of the coil shows coil is good - internals must not be compatible with gasoline. Time to search for a different valve...

[67c&ccorv]

This is the valve I have;

http://www.dan-marcrvparts.com/79afc121r.html

I also got the inline filter with magnet;

http://www.dan-marcrvparts.com/infiwima.html

[Al Schober]

The saga continues.. Went to the boat Sun afternoon to go for a sail, and the engine acted up again. Again, fuel starvation symptoms. Cycling the adjustable main jet didn't improve things, so I pulled the carb to bring it home for a thorough cleaning per the book. Got to that this morning.
Only thing I found was that the inlet to the float valve was clogged with something that looked like fine sawdust. With the float and needle removed, I couldn't even blow through the seat!
Obviously coming from upstream through two filters - naaah, can't believe that. Main filter is a new (last year) Racor, secondary is a brand X lawnmower filter. Perhaps the secondary filter is dissolving???
Plan is to remove secondary filter, run the Facet pump to move some fuel (1.5L) through the main filter into a glass jug to be checked for clarity. If clear (I suspect it will be) I bring home the secondary filter and do an autopsy (with assist from my band saw). Might even get some good photos (grin).

[Dave Neptune]

Al, hope you find something amiss in the filter. It could still come from the cavity that feeds the N&S as it is large and has three ports already drilled on some models. Remove them all and give the cavity an air hose enema.

I have cut into many a filter and only found very few with a problem!!!! The filter you speak of is a cheepy and maybe it did come apart a bit.

Dave Neptune

[Al Schober]

Removed the second fuel filter today and pumped a quart and a half into a glass jug - nice clear gas. Installed a new secondary filter, reconnected, and all seems well for the time being.
Brought home the old filter and took a saw to it. First cut was around the outlet end but that did nothing. Seems the paper filter is set into some sort of mastic in the outlet end of the can. Second cut was at the mid flange allowing the inlet half of the can to be removed. Wow! The end of the filter fails the magnet test and shows 'rusticles', which are loose. The can also fails the magnet test and shows corrosion. The particles in the inlet port that look like sawdust are also evident in the outlet port, and are apparently what clogged my float valve inlet.
So IMHO, the polishing filter that's supposed to be the last defense is what caused my problems and caused me to lose a month of sailing. I'm going to rethink using a polishing filter unless I can find one that passes the magnet test.