Could someone please identify two things in this photo taken in my '77's trunk just under the fuel fill? One is the white cylindrical plastic piece with hose on each end. The other is the larger black cylinder with several hoses coming out the bottom. Thanks Forum!

Well, obviously, one is a black thingy and the other is a white thingy...

Go to the next one...

LOL!!

That's great.

I was getting worried that I was the only one who had a sense of humour here.

Funny.

Jim

Oh damn!...I mean, oh darn.

I've double posted.

Those 2 things are part of the evaporative emissions control system. The black cylinder on the right with the hoses collects fumes from your fuel tank and and then routes the fumes over to that 3 way valve on the right which is a spring loaded device that allows make up air to enter the fuel tank and gas vapors to be routed to the charcoal cannister in the engine compartment.

Thank you Blazing Spider. See, we all learn something here. Any maintenance needed on these?

Other than replacing cracked and brittle hoses no regular maintenance required. You could check the black plastic collector to make sure there aren't any cracks in it.

That being said there is a little thin foam air filter on the back side of the 3 way valve. Over time, it can disintegrate. Mine did and I cut a piece of foam out of one of those foam paint brushes to replace it with. I don't believe that valve is available anywhere anymore.

blazingspider wrote:Other than replacing cracked and brittle hoses no regular maintenance required. You could check the black plastic collector to make sure there aren't any cracks in it.

That being said there is a little thin foam air filter on the back side of the 3 way valve. Over time, it can disintegrate. Mine did and I cut a piece of foam out of one of those foam paint brushes to replace it with. I don't believe that valve is available anywhere anymore.

Is that the same valve usually under the car above the rear axle, or are there two check valves in the evap system? I'm getting pressure in the tank blowing out when I open to fill. For now I open the cap every time I park it, but I believe this is the root cause...

The 2-way valve above the rear axle, driver's side, (on your '80) is likely clogged, and the gas tank is pressurizing while sitting in the sun, thus you get the whooshing outgas when the gas cap is removed.

Normally the valve lets these fumes pass through the charcoal canister (losing some HCs along the way) and out to the atmosphere through the cap at the top, or be drawn into the intake manifold if the engine is running.

Fiat changed the evap emissions system solution over the years. Cars with the 3 way valve in the trunk do not have a check valve underneath the car by the rear axle.

Mine has the 3-way part, with the 3 hoses in and 1 out, but it is smaller and works as a fume collector (and assumed liquid separator).

Maybe he has a sealed replacement cap when a vented cap was original on his configuration?

Pete

RRoller123 wrote:Mine has the 3-way part, with the 3 hoses in and 1 out, but it is smaller and works as a fume collector (and assumed liquid separator).

Maybe he has a sealed replacement cap when a vented cap was original on his configuration?

Pete

Hmmm, my gas cap was cracked and I believe John Erskine sent me a replacement. I have an orangy vavle in the trunk and another above the rear axle. I guess I'll replace it and see, though I'm not sure how to get the hoses (weird looking clamps) off...

I definitely have the red 3 in, 1 out in the trunk and the 2 way above the rear axle. I removed the valve under the axle and it was full of grey gunk as was about the first inch of hose leading into it. Had plenty of slack in the trunk to push some through the bulk head and snip the clogged end off above the axle. I also took the time to disconnect the "3 way" in the trunk and blow compressed air through confirming the line is clear. Hopefully this isn't a problem for another 30 years...

I don't have the schematic for the carb'ed version, but here it is for the FI. The 2-way valve has a slight difference in pressure required to activate it.