84' 90hp Merc...Leaky Lower Carb (UPDATE)

[OBJ]

Need some help/advice from you Merc Experts.

The topic engine is an inline six, three carb engine. It sat for about six years.

Pulled all three carbs, soaked and cleaned. Installed new OEM needles/seats and floats. Installed the carbs and put the gas to it. Bottom carb flooded.

Rechecked the float spring and needle levers. They were good. Carb flooded again when primer was pumped.

Switched carbs. Middle to lower. Same results. Lower carb floodes.

Am I missing/don't no something here?

Jim

 

[Chris1956]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

Jim, It sounds like you went "by the book". Not too sure what I can suggest. Mayve you can reset the float in the bottom carb to be a bit lower. Also, there are small washers that seal the inlet needle seat. Did you install those? I guess the third issue is whether you installed the correct needles and seats. Mine are steel needles with neopreme on the pointy end, and solid brass seats. You might check the OEM part number of the new seats against the info at www.dougrussell.com, for your motor.

 

[OBJ]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

Checked all that Chris. That was a first thought for me also. The parts breakdown indicated the same PN for all three carbs as did the parts book. Seat washers are in place. I also tried setting the needle lever (the one that goes against the float spring) just a tad high.

I don't know......I think the gods of Mercury's are peeved at me.....LOL!

Thanks for the come back Chris.

 

[OBJ]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

(Bump) Anymore suggestions or advice? It still floods.

 

[xmen3]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

It is the same deal with my '86 115.
If I pump the ball till its really hard, all 3 leak, then the top 1 stops, then the middle 1 and finally the bottom.
I replaced all the seats and needles to no avail.
It is worse if the motor is trimmed forward and not as bad when trimmed down all the way.
It is bad engineering.The floats are too small and dont exert enough pressure to keep the needles shut tightly.
Thankfully it dosen't seem to be a problem when it is running but I have to wonder why mercury put a tray under the carbs to catch the leaking gas and drain it out of the motor.

 

[OBJ]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

I'm going to crank it up and see what happens. I know Merc's do this but it's just agrivating as all get out.

Thanks X for the come back.

 

[Clams Canino]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

Perhaps you are just squeezing too hard.

-W

 

[OBJ]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

I dunno clams......I'm used to pumping the bulb up till firm. Is this problem just on the side mounted float bowl? Seems other Mercs with the float mounted in the bottom of the carb don't leak to easy.....unless of course the needle is shot. I'm going to crank it tommorow and see what gives. Hopefully the bottom carb will hold after the engine is running.

 

[Clams Canino]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

I personally hate bottom bowls. I've hated them since I was 12 when I first met a Techumseh lawnmower.

-W

 

[gregtobin]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

I have a 74 1150 inline 6. When I overpump the bulb, the top carb leaks from a fitting that supplies gas from the fuel pump.

Is your carb leaking while it's running or just when you're priming?

 

[OBJ]

Re: 84' 90hp Merc...Leaky Lower Carb (UPDATE)

Stuck the critter back together and dumped it in the tank.

Didn't squeeze the primer to much. Cranked her and she fired and ran. Few tweaks and it idled very well. No fuel from any of the carbs while running.

But some fuel ran out of all the carbs after I shut it down and tilted the engine to remove it from the tank.

Comments anybody?

 

[Chris1956]

Re: 84' 90hp Merc...Leaky Lower Carb (UPDATE)

Sounds like you have it fixed!

 

[Clams Canino]

Re: 84' 90hp Merc...Leaky Lower Carb (UPDATE)

Ya.. leaking when tilted is perfectly normal.

-W

 

[daveswaves]

Re: 84' 90hp Merc...Leaky Lower Carb

Re: 84' 90hp Merc...Leaky Lower Carb

Perhaps you are just squeezing too hard.

-W

Just as an fyi, with a fuel pressure gauge in line when you squeeze that bulb it is easy to get 10 to 12 psi, way more than the float and needle can hold back on one of these.:%