90 hp carb over filling

[That old Mercury]

Hi
I have bought a boat and the bottom carb was flooding through the vent tubes. Carbs had been worked on prior to purchase.
Rebuilt both carbs and bottom carb leaking with air pressure test.
Swapped bowls and tested again and it had a small air leakdown
Lapped needle seat and that stopped the leak.
Put carbs back on pumped bulb and gas was leaking out the vent again only after a few days sitting.
Checked plastic bowls on both and they were warped.
Sanded both bowls and no leaks for 2 months on top carb , now back to leaking , flipped gasket over and done a leak down test No leaks.
What i see it gaskets starts leaking between the carb and float bowl so it fills the carb full of gas and it over flows the carb.
Does anyone know of a metal bowl replacement for this carb?
335830-CS or it may be 09
Float chamber #398 544

 

[racerone]

Model # of your motor?----Aluminum bowls may be available at US $177 list each.

 

[That old Mercury]

Model # of your motor?----Aluminum bowls may be available at US $177 list each.

Hi
It will be a few days before i get back to the boat to get the Model #
I will post it when i get it.
Thanks

 

[cyclops222]

Plastic carburetor parts were installed to provide repair money for the dealers.

 

[racerone]

??----Plastic parts are cheaper to produce.-----It is all about being able to market a product for the showroom.----Not designed with future repairs in mind !!

 

[That old Mercury]

??----Plastic parts are cheaper to produce.-----It is all about being able to market a product for the showroom.----Not designed with future repairs in mind !!

So true.
I think i have it figured out.
Its been years since i tested one and i cant remember the psi.
I think by squeezing the primer bulb till its firm is pushing the rubber gasket out of place.
Fuell pump pressure depending on rpm is roughly 1 to 2-1/2 psi.
Who knows what psi the primer bulb produces for a 5/16" line ?
I dont have a gauge handy but i bet its a lot higher!
Thanks

 

[saltchuckmatt]

One other way to look at it. Did you look at the torque specs for the screws that go in the plastic bowl?

You might find.... that you're over torquing them.

Cheap to try....

 

[That old Mercury]

One other way to look at it. Did you look at the torque specs for the screws that go in the plastic bowl?

You might find.... that you're over torquing them.

Cheap to try....

Hi
They were torqued 10 inch pounds .
When i took them apart the first time after i bought the boat to put in kits they were so tight i thought i was never going to get them out with a screw driver.

I thought about the high gas tank pressure also, it was the plastic EPA non atmospheric vented type. In the sun it would expand in all directions 1/2", i measured it cool and hot, heck you could see it deformed . Crack open the cap and it was a loud swoosh !
It actually blew the cap off going down the highway, got to the lake and gas was everywhere in the boat! Gas cap No where to be found.
I always opened it just a little when boat was not in use and closed it while trailering and fishing
And i know it was closed tight the day it blew off 100%.
Thanks to Everyone for the responses.

 

[saltchuckmatt]

Sounds like your gas tank vent is plugged.

Does your boat have a second vent?

You purchased new plastic bowls, correct? I buy new ones and have no problems.

 

[Faztbullet]

Toss that EPA tank and pick up a couple of old metal tanks. Find em on marketplace $25 and up

 

[saltchuckmatt]

I assumed with a 90hp you have an onboard fuel tank. Are you using portables?

 

[That old Mercury]

Sounds like your gas tank vent is plugged.

Does your boat have a second vent?

You purchased new plastic bowls, correct? I buy new ones and have no problems.

The Epa tank i had only allowed air in. Cap had a one way check valve
The Epa rule on new plastic tanks is they cant vent fuel to the atmosphere
Or thats what i have read

 

[That old Mercury]

Toss that EPA tank and pick up a couple of old metal tanks. Find em on marketplace $25 and up

View attachment 397665

Thats the way to go for sure.
I have lung problems so i stay away from gas fumes.
I got a gas tank i bought for my bass boat an aluminum fuel cell without the foam inside, moved it to the front of my center console and ran new fuel line to my fuel water seperator.
To follow Coast guard rules i made everything detachable including the fuel level sensor wires.
Will try to attach a picture of the tank from the website i purchased it.
Is it legal? Guess next inspection will prove it out. Worst case i get a good old metal tank and just swap it out!
Thanks

 

[That old Mercury]

I assumed with a 90hp you have an onboard fuel tank. Are you using portables?

Onboard tank supposedly had a leak, original owner used a portable.
Would have to cut the floor out to remove the tank to check it.
I aint doing all that for sure.
Could be a fill hose leak or a fuel line, thier is only a 4" hole in hull to change the fuel level sensor.
The boat is a 17' scout

 

[That old Mercury]

Sounds like your gas tank vent is plugged.

Does your boat have a second vent?

You purchased new plastic bowls, correct? I buy new ones and have no problems.

Sorry forgot to reply to the bowl question.
Yes plastic bowls, i have only sanded both of them as flat as possible on a granite top and sand paper.
I have just been testing the boat and fishing to find all the problems first, then i will order from thier.
I missed out on the carb plastic years when they came out.
I had moved to big block inboards during that time i guess

 

[saltchuckmatt]

One way vent is tough. Maybe get a charcoal canister and rig up a evap system. Couldn't be that hard. I'm doing it to my 1974 Grummen and step van as we speak.

I had a 19 ft campion cc and I cut the tank out. Cut the floor out with a skill saw, replaced the tank and put in a stainless steel beauty ring to hide the cut marks. That's ballast, you want the fuel down there.

Buy new bowls, the only way to go.


See the ring in the picture?

 

[That old Mercury]

One way vent is tough. Maybe get a charcoal canister and rig up a evap system. Couldn't be that hard. I'm doing it to my 1974 Grummen and step van as we speak.

I had a 19 ft campion cc and I cut the tank out. Cut the floor out with a skill saw, replaced the tank and put in a stainless steel beauty ring to hide the cut marks. That's ballast, you want the fuel down there.

Buy new bowls, the only way to go.


See the ring in the picture?

Very nice looking boat.
The Scout rides low in the back with the 12 gallon plastic tank, full its 72 lbs , then i have 2 large deep cells batteries , 6hp kicker and 2 trolling motors plus the 90 hp johnson.
I already put 3 large anchors in the very front which got the nose down which helped a lot.
I put the aluminum fuel cell in front of the console where the bench seat was at some time to get more weight to the front.
I have not tried it to see how the boat sits now.
The old tank is under the console so it would have to be removed to cut it out. I cant breathe with a dust mask on and i dont care about itching for a week from fiberglass LOL.
Thanks for all the help

 

[saltchuckmatt]

Very nice looking boat.
The Scout rides low in the back with the 12 gallon plastic tank, full its 72 lbs , then i have 2 large deep cells batteries , 6hp kicker and 2 trolling motors plus the 90 hp johnson.
I already put 3 large anchors in the very front which got the nose down which helped a lot.
I put the aluminum fuel cell in front of the console where the bench seat was at some time to get more weight to the front.
I have not tried it to see how the boat sits now.
The old tank is under the console so it would have to be removed to cut it out. I cant breathe with a dust mask on and i dont care about itching for a week from fiberglass LOL.
Thanks for all the help

Well, I'd move the batteries forward and vent them.

I cut the fiberglass with my electric water diamond blade hooked up to a shop vac....an old Milwaukee to be exact.

I put on a light dusk mask on, and threw it away, didn't need anything. All these tools I got for free. Baby boomers are retiring in masses and the whole market for stuff has crashed.

I call it stuff management, in more colorful colors.

Put your mind to it and anything can be done!

How's your mind?

 

[That old Mercury]

Well, I'd move the batteries forward and vent them.

I cut the fiberglass with my electric water diamond blade hooked up to a shop vac....an old Milwaukee to be exact.

I put on a light dusk mask on, and threw it away, didn't need anything. All these tools I got for free. Baby boomers are retiring in masses and the whole market for stuff has crashed.

I call it stuff management, in more colorful colors.

Put your mind to it and anything can be done!

How's your mind?

My mind is excellent!
Used to design and fabricate industrial equipment, body just weak! Too many welding fumes and chemicals back in day before fresh air mask came out.
My right arm just had a run in with a diamond blade and the ER! They are Awesome ! Just be careful cutting thin metal sheeting.
If it ever quits raining i gotta finish my install and try it all out.
Thanks to Everyone for all the help.

 

[saltchuckmatt]

My mind is excellent!
Used to design and fabricate industrial equipment, body just weak! Too many welding fumes and chemicals back in day before fresh air mask came out.
My right arm just had a run in with a diamond blade and the ER! They are Awesome ! Just be careful cutting thin metal sheeting.
If it ever quits raining i gotta finish my install and try it all out.
Thanks to Everyone for all the help.

Right arm is awesome?...diamond blade is awesome?....or the ER folks?

Probably all 3 I guess.

Best of luck to you.