Fuel never stays in my carburetor

[dn010]

So I've got this ongoing problem where my carburetor bowl keeps turning up dry every time I go to start the boat and it's getting a bit irritating having to use an inline bulb to prime every time. It won't even last a few days without the bowl mysteriously going empty. So, aside from the obvious (fuel lines & fittings), what else can I check on or in the carb to find out why this is happening to me? It's been doing this for years now, and I rebuilt this carb twice with no change. This carb is a Rochester 2bbl perched on a Merc 470 and it happens whether the engine is hot or even if the engine hasn't been on - I can go fill up the carb at night, not run the engine and come back a day or 2 later and its low or empty. The 4bbl on my 350 stays with fuel in it forever it seems! Thanks in advance for any info.

 

[sti1471]

Re: Fuel never stays in my carburetor

take the carb off the boat. Fill the bowl with fuel and put the lid back on or leave it off. Place the carb in a bowl or bucket and let it sit there for a day or so. Check on it every so often and see if the bowl it is sitting in is filling up with fuel.

This can let you know the rate at which it is leaking out, and if it is leaking out or just evaporating by chance.
it might also show you where it is leaking from.

Sounds like there might be a small hairline crack in the carb body that the fuel is slipping past but is not visible to the eye.

 

[dn010]

Re: Fuel never stays in my carburetor

Thank you for the reply and info - I'm going to try it and see what happens.

 

[dn010]

Re: Fuel never stays in my carburetor

So it's definitely leaking down, It's hard to tell where it's originating from - maybe a crack like you've suggested, so I believe it's time to trash this carb and go with a new one. Thank you again for your suggestion!

 

[sti1471]

Re: Fuel never stays in my carburetor

if you are going to trash the carb anyways, open it up and see if it might be something simple first.

-remove the 2 jets from the carb. Do you have stainless steel washers between the jets and the carb body?
-remove the power valve assembly, do you have a stainless steel washer between that and the carb body?
- does your spring loaded rod attached to the carb lid move smooth up and down, or does it get stuck or have rough spots in the movements? (if your spring rod is getting stuck, then it might be pressing down on the power valve somewhat when your boat is not running, thus draining the fuel out of the bottom of the bowl)

- Remove the venture cluster. how does the gasket look?
-Under the venture cluster there is a hole with a T bar in it. Remove that T-bar and there will be a little spring under it. Under that spring there should be a little check ball. Is the check ball there? it should be made of steel, not aluminum. If it is missing or the wrong ball, you need to get a new one. If that check ball is not making a good seal, then gas is coming up that chamber and leaking out the venture cluster.

 

[dn010]

Re: Fuel never stays in my carburetor

I can say with certainty that there are no washers under the jets however the power valve has one, kind of like a fiber ring - not stainless. The rod is working fine, gaskets are good the only thing I'm not sure about is if the check valve is steel or aluminum, either way I should have a replacement from one of my many rebuild kits for this thing.

Something else I forgot to mention is that at some point there was water intrusion in the carburetor. My guess is it ran down the engine hatch, down and in the arrestor and then down the throat. The bottom steel base plate was rusty and there was rust drips inside the aluminum intake so I know it had to be water dripping down. Of course I rebuilt from that point, cleaned it all up got rid of the rust & made sure the passages were clear. I'm not sure if this situation would have caused any additional problems for me or not because now there are some pitted areas...

I'll tear into the carb again tonight and see if by installing some stainless rings I can get less/no leaking.

 

[Eric 3.7LX Alpha 1]

Re: Fuel never stays in my carburetor

Do some research on your Welch Plugs, happens to many Rochesters.

Quadrajet welch plugs? supplier? - Hot Rod Forum : Hotrodders Bulletin Board

 

[dn010]

Re: Fuel never stays in my carburetor

Alright I just had a chance to do a little bit more with the carb. So today it's pretty wet around the venturi and seeping down the throat - the plates are wet. Jets definitely do not have steel washers, the tiny power valve needle just kind of floats in the valve - I thought it was supposed to be under spring tension? The venturi gasket looked fine and the ball is made from steel. Welch plugs while a great suggestion don't seem to be the cause, I checked mine and all seems well-for now LOL. So obviously I need to do another rebuild on it. While I wait for a rebuild kit to arrive I'm going to get another carb, preferably one with only 1 needle adjustment instead of 2 like I have. While it's on my mind, would the needle/air mixture cause me to have top end issues?

Thank you guys for your help and suggestions, I'd love to have this issue resolved.

 

[dn010]

Re: Fuel never stays in my carburetor

Alright so I guess I'm down to the point where I am looking at/in my carburetor and I realize I can toss as many rebuild kits in it as I want but it will never truly be right. I'd like to go with a reman.

So, now my question is this: My carburetor number is 17057132, do I have to stay with this same carb number or are there any newer, updated ones; any alternatives? Of course I need the same base bolt pattern... Thank you in advance for any info.