carb leaks at throat, no float seat available

[rcb130]

Hello All,
I am working on a 2002 Merc two stroke 15hp. S/n OT531949, model 15M.
I cannot find a carb kit with a float valve needle seat, only a needle.
How is one to rebuild the carb without a new float valve needle seat? Everytime I try it, the carb still leaks.
Is there a trick or secret to stop the leaks?
thanks in advance
rcb130

 

[flyingscott]

Have you adjusted the float.

 

[alldodge]

I'm not an OB guy, but looking at the parts diagram I don't see a removable seat. If that is the case, then need a tool to resurface it

https://www.mercruiserparts.com/bam/subassembly/28162/3234/70

Look forward to hearing what the OB guys say

 

[flyingscott]

Did you replace the primer diaphragm and spring? You should not need a new seat those needles are nylon tipped. Is your float in good condition? Is it full of gas and not as floatey? If the float is in good condition adjust the float!!!!!!!!!!

 

[rcb130]

I have replaced everything that comes in the rebuild kit. Yes, I have adjusted the float. I have rebuilt several of these carbs on the small mercs and they always leak afterwards.
I have rebuilt omc carbs with new seats and no leaks.

 

[alldodge]

have rebuilt several of these carbs on the small mercs and they always leak afterwards.

Might want to get someone else to do it

 

[rcb130]

AllDodge,
very professional response. thank you.
Is this how you get so many posts credited to you?
If you cannot respond with helpful information, please do not respond
rcb130

 

[GA_Boater]

AllDodge,
very professional response. thank you.
Is this how you get so many posts credited to you?
If you cannot respond with helpful information, please do not respond
rcb130

Why is your nose out of joint? AD made a very valid reply and I took it as have the seat resurfaced. Nothing wrong with that suggestion.

 

[flyingscott]

I have rebuilt well over 50 of those carbs and have never had to resurface the seat. If you have done several and they all leak it is probably how you are assembling them. They are not as easy as an OMC carb but not that difficult either. You may want to get a manual on how to.rebuild those carbs. It will also have the specs for the float setting.

 

[Sea Rider]

Is the float adjustable or it's a fixed one ? Is fuel leaking after primer bulb was pressed firm, not stone hard or while the motor is a idle or running ? if so, seems the valve needle is not closing properly against the valve seat. if the seat is not pitted, corroded maintains its round shape there's an easy maintenance fix for the leaking issue, but first answer both questions to go from there..

Can understand the OP's frustration not to receive a proper answer about solving his leaking issue fast enough.

Happy Boating

 

[rcb130]

flyingscott,
I have the merc shop manual and I set the float at 1".

Sea Rider,
Float is adjustable and to be set at 1".
Leaks after pumping primer bulb till firm. motor idling.

GA_Boater,
my nose was out of joint over AD's comment "to have someone else do it".
uncalled for in a forum intended to help one another.
rcb130

 

[GA_Boater]

Sometimes that is the best advice. You have to recognize your limitations. You say every one you've rebuilt leaks and others say they have no problems with multiple rebuilds. What can we think?

As much as I hate to admit it and I've been working on stuff for a long, long time, I have had to pay someone when the fix is beyond my skill or knowledge level and I wasn't happy. Such is life.

I have some questions;

Leaks after pumping primer bulb till firm. motor idling.

If the motor is not running, after squeezing until the bulb is firm, does the carb leak?

Is the leaking only when squeezing the bulb while the motor is idling?

 

[flyingscott]

Why r u pumping the ball after it is idling. I am guessing you are using a seloc or clymer. Try 1 1/8 -1 1/4 for the float level.

 

[Sea Rider]

What's the use/idea of priming the bulb when motor runs at idle, should prime the bulb till firm before starting the motor specially if running the carb dry or when hose and tank has been removed. If the fuel line along the fuel tank remains hooked and motor is turned OFF, no need to prime bulb again as long there's sufficient fuel in the tank to carb circuit.

Happy Boating

 

[Faztbullet]

What difference does it make if its running or not as when bowl is full needle should stop all fuel from entering bowl whether by fuel pump or primer bulb. Now if the fuel leaks by the check ball in primer circuit it will cause leakage..

 

[Sea Rider]

What difference does it make if its running or not as when bowl is full needle should stop all fuel from entering bowl whether by fuel pump or primer bulb. Now if the fuel leaks by the check ball in primer circuit it will cause leakage..

Touche!! that's how it was designed to work, not an issue with it, my post was all about what some boaters likes doing on their motors..

Happy Boating

 

[Sea Rider]

If fuel is overflowing carb after bulb has been primed to a firm condition, it's definitely a needle & seat tech issue, carb components not doing their homework right. Hope this valve cleaning suggestion ends OP's frustration :

Needle tip must be sharp pointy, not rounded, degraded and needle valve not pitted, corroded in order for this cleaning procedure to work spot on.

-With removed float and needle, turn carb upside down on a flat surface.
-Get a wooden sushi stick and roll a thin piece of cotton on tip like similar to a cotton swab.
​​​-Dampen in water, roll again cotton on tip as to have it sitting firm and doesn't fall off when cleaning.
-Put an overdose of toothpaste of your preference brand on tip
​-Insert tip on valve, with hand palms holding stick in middle, spin tip firmly down on valve as when polishing valves on a motor block.



-Remove stick, cotton swab will usually comes out dirty
-Dispose old cotton and install a new one with more toothpaste adhered to it.
-Repeat this process till cotton comes out clean.
-Install needle and float.
-Change the middle carb gasket for a new one, faulty gasket will also spill fuel from there as well.

Report after deep cleaning if the fuel overflow was canceled....

Happy Boating

 

[flyingscott]

What difference does it make if its running or not as when bowl is full needle should stop all fuel from entering bowl whether by fuel pump or primer bulb. Now if the fuel leaks by the check ball in primer circuit it will cause leakage..

You want to know what difference it makes!! Because why is it being pumped after it starts? Is the fuel pump not working correctly? Is it the wrong base gasket restricting it? Why are all the carbs he is rebuilding doing the same thing??? Why are all these seats bad? Are they being salvaged off of the bottom of the ocean? Is he cranking the carb down to tight and cracking t he fuel.pump spacer? Good.luck with your motor I am sure toothpaste and a q tip will fix it.

 

[rcb130]

Sea Rider,
Your suggestion to polish the seat worked like a charm. Reassembled carb with no leaks. Installed on motor and set up idle and mixture per manual and no leaks.
thanks again for your tip
Be Well
rcb130

 

[Sea Rider]

Sea Rider,
Your suggestion to polish the seat worked like a charm. Reassembled carb with no leaks. Installed on motor and set up idle and mixture per manual and no leaks.
thanks again for your tip
Be Well
rcb130

Thanks for posting back end results, this procedure works like a charm on any carb, the issue is that everybody bypasses the needle valve seat condtion and begins fingering with float heights that doesn't need to be fingered as floats are correctly height adjusted at the carb manufacturer. As you have witnessed toothpaste is an incredible valve seat polisher. Be Well and enjoy boating again..

Happy Boating