TOPIC: Gas pouring from carb...

I took Corson to the ramp today and never made it off the dock.
Previously, the engine would fire right up and run until you gave it full throttle and it would die.
then it would be hard to start, but once it started you would have to ease into it to go any where...

Today it was very hard starting, and would only run with the warmup lever all the way forward.
I noticed gas in the water... Then if I crimped the fuel line it seemed to run better. Anyway, I put it back on the trailer and took it home. I started it on the muffs in the driveway, and took the cover off and there was gas just pouring out of the top carb... The thing was just flooding all over.
It is a 1977 merc 500. New moeller tank. What are your thoughts?

Thanks
Oct.

Kinda sounds to me like a stuck float or trash in the carbs, Oct. Have you been through (cleaned and put fresh gasket kits in) the carbs and fuel pump?

yep...stuck floa..although mine was made of plastic and developed a split and filled up with gas.

Due for a carb rebuild - actually sounds like they're past due for a full disassembly, cleaning and rebuild with new, ethanol resistant carb kits with fuel pumps. That should fix your acceleration issue as well.

Awesome! Thanks guys...
I figured that would be the case.
So I assume I need two kits, one for each carb?
How do you know it's an ethanol resistant kit?
I should get the kit with the needle and seat right? Should I get new floats too, or wait to see what mine look like?

Thanks for all your help!

october

I would also need 2 fuel pump kits as well right?
Also where Do you guys usually buy your carb and pump kits from?
Thanks again,

oct.

I believe the fuel pump kit is part of the carb kit, as the pump & carb are all the same assembly.

Most kits these days are indeed ethanol resistant. Only exception might be someone offering a new old stock kit from the 1980s or earlier... If you get kits from a Merc dealer you should be okay...

Ok, so I found the kits at a local napa...
One is a carb gasket kit, and one is a fuel pump kit.
After a few online searches it seems there is not a needle and seat available.
Having never done one of these carbs before, are these all I need? And I need 2 of each, correct?
The 2 carbs are from the 77 merc 500, and the carb number is BA-3B 713

Thanks!

oct.

It appears from the pics that the fuel pump gaskets are included in the carb kit, but not the rubber diaphragm?
So I have to get the fuel pump kits to get the diaphragm?

I think you may need more. I don't understand why mercs are like this.
Check out marineengine.com.
OMC kits come with everything. I am running into the same issue with a late 80's 25HP. The full carb kits are expensive and hard to find.

So what you are saying is that I need the $80 carb kit...
One for each carb...

You might check the carb parts listing on this site:
www.maxrules.com/index.html

These guys are old school Merc nuts and very nice to deal with. I bought carb kits with needles/seats, plus separate fuel pump kits, at a good price. (Around $60 for 2 carb kits and 2 pump kits. Could have been much less without the needle/seats.)

(edit) I looked again using your BA-3b carb numbers. They are listed and pretty reasonable too. So are the fuel pump kits.

Not sure if your 77 motor will be listed. You need either the motor serial number or the carb numbers to search their database.

Norm

Hi,
As I grew-up with Mercurys, I am very comfortable with the idea of selling the carburetor items in separate components. In some circumstances, this is an advantage.
I would recommend the purchase of the carburetor gasket kit, inlet needle assembly, and fuel pump diaphragm kit ($15.92 per carburetor using aftermarket brand parts). Only if the float is fuel logged, cracked, or has noticeable wear from contact with the inlet needle, would I suggest it's replacement.
The carburetor repair parts kit mentioned (@ $80) contains carburetor hard parts which are typically not needed. Most often when hard parts are required, it is due to damage to components during disassembly (the use of rounded-off, or improperly sized, slotted screwdrivers, or further disassembly than is really needed required with the use of carburetor acid type "dip" cleaner, which I do not personally like or use, has been the "why" I have personally seen).

Regards,
Joe
www.fergusonpoolemarine.com
This email address is being protected from spambots. You need JavaScript enabled to view it.

Joe Poole knows these old Mercs inside and out, and runs his business the way we remember from the good old days. I should have mentioned him in my previous post. Joe recently spent a ton of his time helping me decide on a correct replacement prop for my old Merc 650. Take a look at his website, or give him a call. You won't be disappointed.

Thank you everybody for all of your help...
I have already got the gasket and fuel pump kits.
Joe, if you think I need the inlet needle assemblies,
then I will get those as well, I will send you an email...

I'm sure I will have more questions as I take these apart...

Thanks again...

october

I got those carbs apart...
The one that was leaking gas, did have a stuck float, it was caught on a little brass baffle piece.
They both had dirt and debris on the screens, and all the gaskets were hard and brittle. The rubber fuel pump diaphragms were stiff like poster board. Got one cleaned and assembled except the float/bowl, as I'm still waiting for the needles I ordered from Joe Poole. The other is disassembled and in the vat.
I'll update as I get things back together...
Thanks again to everybody for their help.
Oct.