no fuel through carb

[Brosov]

Long story short, I have spark, but no start. I get fuel through the fuel pump, but apparently not through the carb. I've taken the carb off a few times and cleaned it thoroughly. But somehow, gas is still not getting through, I think. What could be imeding the flow through the gizmo? The float seems to be set correctly and the needle drops out of it's seat when the float doesn't press up on it. Grrrrr. Any ideas on where the issue could be coming from?

[hanleyclifford]

If fuel is filling the float chamber but not getting to the engine, the next place to check is the main jet. It is safest to take the carb off the engine to check this because the parts are so small. You could take the plug off the back of the bowl first to see if indeed fuel is getting to the float chamber. It is real easy to drop this plug into the bilge!

[roadnsky]

If fuel is filling the float chamber but not getting to the engine, the next place to check is the main jet. It is safest to take the carb off the engine to check this because the parts are so small. You could take the plug off the back of the bowl first to see if indeed fuel is getting to the float chamber. It is real easy to drop this plug into the bilge!

For clarity, here's a pic of what Hanley is talking about...
Watch out for that little washer in there!

[Brosov]

Thanks, guys. When I pulled the carb off last time, I noticed that the float chamber was only partially filled (maybe about 1/5 full?). Is this "normal", or would I expect that sucker to be filled more? Also, I've gotten away with using the same old gaskets each time I have rebuilt the carb... they have no visible wear, but maybe air is somehow leaking in causing a poor vacumn??

[sastanley]

Brosov, on re-using gaskets, & leaks, etc.., possibly..I've found you can add one more life to gaskets with a sealer too (like Permatex, RTV/silicone in the carb will get destroyed by the fuel), but once you add the Permatex, you are likely going to need to replace it the next time around. I print out the gasket sheet from Moyer and think about my plans for the future regarding maintenance & check off x1, x2, etc....the gaskets themselves are not expensive, but it seems silly to pay UPS shipping for only one or two...I get my list together for the ones I know I need, and in addition to that, try to have a spare for anything I might need to take apart & service while sailing (carb bowl, thermostat, carb/manifold flange, reversing gear cover, water pump, etc..) in case one of them doesn't come apart easily and tears.

I haven't quite thought I needed a spare head gasket(s) for example, but when I was little I remember hearing stories about another boat with an Atomic 4 & the Dad & son would replace the head gasket on the fly during the day while sailing between ports, so I guess they carried a few around.

For things like the carb gasket, or t-stat housing, I think I assembled mine last time with Permatex #3 on one side only, that way it would hopefully stick to one piece and come off clean on the other side when taken apart..success remains to be determined.

You might spend $50 on gaskets, but $40 of that is spares sitting in the box ready to go.

[Marian Claire]

As usual more questions than answers. What is your fuel system set up? Tank, filter, pump, polishing filter??? Have you checked for good fuel flow at the connection to the carb? Dan S/V Marian Claire

[smosher]

When you take the carb apart make sure you poke through all of the holes, jets, and vents. Just blowing carb cleaner will not unclog some of the deposits.
I use a thin piece of wire.

Steve

[Brosov]

good suggestions, everyone- thanks. I currently have the fuel system set from tank > filter > pump > carb. I ordered an inline fuel polishing kit from moyer and will put it upstream from the carb ASAP. Meanwhile, I'll give it a shot to clear out any jets with a wire as well as the cleaner. I also just cleaned out the sediment bowl from the fuel pump (it was full of a bunch of crud... but I don't think THAT has been impeding fuel flow, specficially). Anyhoo, I'll report my results after I get back to work on her later today, hopefully. If I still have problems, I figure a carb rebuild kit may be in order, huh?

Thanks!

[hanleyclifford]

If you found crud in your pump sediment bowl it is possible that has been feeding it to the needle and seat, main jet and all the way to the discharge nozzle.

[Brosov]

Okay, so I just removed the carb again and noticed that indeed the needle was stuck. And there was a bit of silty "gunk" in the float bowl. Just jostling the body of the carb allowed the needle to drop down as it should.... but I suppose the fact it got stuck is not a good thing and I guess a rebuild kit is needed??

Also, I noticed that the floats themselves had some fluid (fuel, I assume) in them. Not a ton, but I could hear the fluid sloshing around when I shook it. Does this automatically call for replacement? It seems like it still has enough air in them to float and do the job... unless it is a very tempermental and precise mechanism.

After freeing the needle and cleaning everything out again, I reattached it all. I got her to fire using ether, but it died out indicating a continued lost of fuel supply. Carb rebuild kit seems to be the next move, huh?

[Marian Claire]

I do not think the floats should have any fluid in them. The needle valve should drop down without any shaking. Is the black tip of the needle valve on the needle valve? Dan S/V Marian Claire
Edit: What is the definition of “cleaning everything out”?

[67c&ccorv]

Okay, so I just removed the carb again and noticed that indeed the needle was stuck. And there was a bit of silty "gunk" in the float bowl. Just jostling the body of the carb allowed the needle to drop down as it should.... but I suppose the fact it got stuck is not a good thing and I guess a rebuild kit is needed??

Also, I noticed that the floats themselves had some fluid (fuel, I assume) in them. Not a ton, but I could hear the fluid sloshing around when I shook it. Does this automatically call for replacement? It seems like it still has enough air in them to float and do the job... unless it is a very tempermental and precise mechanism.

After freeing the needle and cleaning everything out again, I reattached it all. I got her to fire using ether, but it died out indicating a continued lost of fuel supply. Carb rebuild kit seems to be the next move, huh?

Your floats are leaking and will have to be replaced if they have fuel sloshing around in them.

That is your problem right there.

[hanleyclifford]

I agree with 67 in that the leaking float should be replaced; however I do not think that is the problem at hand. A leaking float would tend to sink or stand lower in the chamber thus letting the needle valve remain open longer than it should thus letting in more fuel, not less. Fuel deficiency is the problem here. It seems that the carb is getting contaminated in some critical passage. The new filter is a step in the right direction. This is not a unique situation. Carburetors all over the fleet are getting "filthified" as ethanol cleans out more and more fuel tanks and delivers the proceeds to carburetors. Multiple filters are our best defence for the time being.

[sastanley]

Hanley...very subtle and eloquent statement. I agree 100%. Fortunately for me, as a new Atomic 4 owner, I had a gas tank failure and had every single piece fresh from the tank to the carb when I started this journey.

Brosov, One common trouble shooting technique here is an outboard tank to the fuel pump with fresh fuel, which eliminates any chance of particles/contamination thru the "house system".

[Brosov]

Good idea re: the outboard fuel tank idea. I'll give that a run. Meanwhile, I think I'm gonna rebuild this carb after all. I need to order the kit, but found inexpensive ones online. The model number I found stamped to the carb is 1374... but that doesn't seem to fit the 5 digit model number I have found elsewhere. Anyone know the typical model # for a late model zenith carb?