metal Quicksilver 6 gallon fuel tank, need a gas cap

[sdowney717]

I got tank for free, but gas cap is missing. filler has diameter of 1.5 inches, tang depth of 1/4 inch
Can I use an auto vented gas cap

Original cap may have had screw down vent.

I dont know the tang depth of that cap.

 

[Fun Times]

How is the fuel gauge lens? You might want to try talking to this guy as while I was searching online "Vintage quicksilver 6 gal metal fuel tank caps" I ran across this guys description near the bottom of the page that says, I also have or can obtain other Mercury parts for these fuel tanks. Caps, gaskets, decals ect. Please contact me for your needs or questions.

Lot of 2 Mercury Kiekhaefer Gas Fuel Tank Lens Repair Kits 3-6-12 Gallon
Mercury Kiekhaefer Gas Fuel Tank Lens Repair Kit 3-6-12 Gallon free cover screws

 

[sdowney717]

Hi, lens is in good shape, can easily read the level.
The Stant cap 10623 is vented. Do you think it has a spring vent valve?
It is made for old trucks and cars.

 

[GA_Boater]

The Stant is an open vent. As in the vent is always open and can't be closed.

Google "Quicksilver 36-18962M" for the cap you need.

 

[sdowney717]

The Stant is an open vent. As in the vent is always open and can't be closed.

Google "Quicksilver 36-18962M" for the cap you need.

Thanks. I looked and found a few.

I also found a Stant 10741 emission cap. It was used in late 70's Fords which were carbed. It is spring vented both for pressure and vacuum, 1.5 inch shallow cam. My thinking is since the Ford trucks used diaphragm fuel pumps and carbs, cap was designed to work with them.
http://www.autopartswarehouse.com/sk...p/ST10741.html gives a description
Stant catalog
http://www.stant.com/files/2714/0979...tage_Guide.pdf

I can call Stant and ask then what PSI it opens at for vacuum and pressure.

 

[sdowney717]

From here, https://www.motor.com/magazinepdfs/122014_5.pdf
"I did find a couple of specs once for a 1998 Ford Explorer. They were: pressure release: 14 Kpa, or 2 psi; vacuum release: 3.8 Kpa, or .53 psi."

Emission caps do vent and release vacuum. 2 PSI won't force a float needle, and .5 suction wont hurt fuel flow out of the tank.
I bought a 6810 Duralast cap for $5.84, they match the 6810 cap at O'reilly's.
It is a perfect fit to this can.
I also dont plan to use this on an outboard boat.

 

[sdowney717]

This closed cell white foam holds up to gas. You can find it commonly used. I think it is a polyethylene foam.
I cut a strip and wrapped it onto the float arm.
Tied with cotton thread.
It cant come off since there is a hook in the end of the arm.
The old cork float was saturated with gasoline.

This is in my old metal Mercury 6 gallon fuel tank.
This tank is real good quality tank, the sight glass for the fuel level is real glass.

 

[sdowney717]

I am not sure the emissions cap is going to work as in let in enough air.
Only thing left is to test with a running motor.
My purpose for the tank is as a spare emergency fuel tank on my inboard boat.
I have the hose and fittings and a fuel manifold valve with a spare input port.
And I could do efficiency testing, easier to determine with a small tank.

I have stripped off the old paint, and also cleaned the paint off the label. That label is pretty tough considering its age.
I used rubbing alcohol and cotton swabs. With time and effort, alcohol dissolves most paints.

 

[sdowney717]

Some more pics. I upturned the tank and it does not leak out the cap.
I sealed the bottom with 'Seal All' as it had 2 holes.
I mixed in 1/32 fiberglass milled fibers with Seal All for the more rusty side that had those two small holes.
I have used this before and it seals gasoline.
I will test it to see how it holds, then coat the entire bottom with Loctite S30 PL roof and flashing polyurethane.











Polyethylene foam works, shows tank half full



imageupload

 

[merc850]

Can't you find a cap at a Mercury dealer, I know I can.

 

[sdowney717]

Sure, but is a lot more money.
I could likely mod this cap with a screw down type vent, if this emissions cap won't work.
I will know in a few days if it will work or not.

 

[merc850]

My concern with that cap is that as pressure builds up it won't be released as you proved when you found that gas won't "leak out".

 

[sdowney717]

Supposedly 2 PSI is the release point. and 0.5 psi is the vacuum relief. My concern is volume, the amount of air flow.
I need to research how the tanks of cars and trucks were vented. Was it by way of the cap and the charcoal cannister.
When I took the valve apart, it would seem to be able to have enough air flow in it's construction.

Combo valve is in center, with valve out of cap, 4 holes are drilled sideways leading to the outer inside edge of the cap.
there is a rubber flat seal ring, on top is a thin metal disc, so somehow between the cap shell and the disc takes place all the venting.

[FONT=Roboto, arial, sans-serif]Evap Vent Valve Solenoid, this is normally open to the air when not powered on, so it vents the fuel system, it is what allows you to fill your gas tank. That valve can flow a lot of air. The emissions cap can also vent the system, but is normally closed.[/FONT]

 

[sdowney717]

Updating the info, been a while but I just finished testing that tank on the boat with that vopr sealed cap and it works. I had two 392 V8's running and an Onan gen set. And they all stayed running. No gas spills from the cap.
If you have an anti siphon valve in your fuel tank, that cap likely offers or less resistance to fuel flow than an anti-siphon valve, certainly not adding any extra.
I don't know what PSI the tank may end up holding before releasing. I have read the EPA mandates for new portable tanks has a high pressure, they can cause carbs to flood. There does exist a fuel demand valve from Attwood which will not flow fuel unless the engine demands it which will fix that problem.

I will leave it out in the hot sun with gas in the tank and see what it does.

I also found out the new EPA compliant PERKO VOPR fuel fills with included tank vent fitting, their cap vents at 1 psi, and sucks open at under .25 psi or say offers no restriction to a pump sucking fuel.