1980 OMC 6 gallon Evinrude Fuel tank

[phuffman]

Fuel tank is creating too much pressure.
Looks like I need to replace the float unit.
Where/who sells these? Really struggling to find.
Thank.

 

[oldboat1]

not understanding. '80 tank would have a vent on the gas cap (would certainly release pressure). Getting build up of pressure from out in the sun? Check bulb and connectors, and make sure the arrow on the bulb is pointed toward the engine.

 

[Vic.S]

All parts of the upper housing are available separately

See the BRP parts catalog at http://epc.brp.com/Index.aspx?lang=E&s1=eb18e298-6d7c-4903-8b72-2ad0f3cafd93

 

[oldboat1]

you mean you have gas coming out of the carb throat when priming, maybe? That might indicate a blocked carb vent.

 

[Vic.S]

not understanding. '80 tank would have a vent on the gas cap (would certainly release pressure). Getting build up of pressure from out in the sun? Check bulb and connectors, and make sure the arrow on the bulb is pointed toward the engine.

I think they might not have appeared until 1981

I think phuffman is refering to the older type of tank with a contents gauge

 

[oldboat1]

Thanks, Vic. Would presumably loosen the cap to relieve pressure, but maybe more involved.

 

[racerone]

The old steel tanks are sealed when the hose is NOT attached.----Allows you to put it in the trunk of the car with no fumes.----When hose is plugged in there are 2 wee pins that are pushed in.-----One is a vent valve.---Other one is a valve that lets gas out.----Much better tanks than some modern plastic junk.

 

[F_R]

It should be noted that the vent is a one-way vent. It lets air in to replace the fuel drawn out, but does NOT allow air to escape. To comply with laws forbidding emission of fuel vapors.

All of this means that considerable pressure build-up from sitting in the sun can happen. I think there is a safety feature that allows air to escape before something blows up though. Not 100% sure on that feature.

 

[phuffman]

Thanks everyone. I will send this to my dad. I think he'll be able to fix the tank IF he can get the parts. It is the "older" style tank as seen in the diagram above left.

 

[racerone]

Those are great tanks.-------Get the new O-rings and " welch plugs " and it is an easy fix.------They do not vent until the hose is attached to the tank.

 

[SweetD]

Here is a great tutorial with pictures and step by step how to replace the o-rings, Welch plugs, etc. I just rebuilt my second tank valve this weekend, easy:

http://www.oddjobmotors.com/tt4_singlelinetanks.htm

I had the unfortunate experience of the old o-rings letting go and the tank self-pumped a few gallons of gas all over my deck!

Dave

 

[jimmbo]

you mean you have gas coming out of the carb throat when priming, maybe? That might indicate a blocked carb vent.

Carb vent?

Fuel pouring out of the carb while priming means high fuel level. Float set too high, Float saturated with fuel, dirty or damaged inlet valve

 

[jimmbo]

I always considered a tank with pressure a convenience. No need to squeeze the primer bulb after switching tanks.

 

[Rustywrench]

Several things to consider here that are more than this man may need to know, but the rest may appreciate. First off a fuel can filled with cool fuel early in the AM and left in the back of a pickup truck in the hot sun can build to 30 lbs of pressure. Discovered this during early VRO day. Easily enough to over come the best carb needle & seats. Also more that enough to power a motor for a long time if the VRO fails (air motor side) & pressure just keeps on supplying raw fuel. F_R & racerone have it right as to why the tank is designed this way. First spills in the back of cars/smells. Then emmisions. Cant have those nasty raw hydrocarbons escaping. Never mind that the plastic tanks grow until they are round & roll all over the boat, junk! IMHO. The pressure is strong enough that over time the back & forth became known as oil canning the tank. Cracks would appear in the bottoms. Just like flexing a piece of steel back & forth till it breaks.