Gassy Pig?

PabloCruise · 09-09-09, 12:54 PM

I would get a strong gasoline smell in my Pig after running for a few minutes on warm days.

I suspected the emissions control device off the gas tank because if I cracked the rear window while rolling down the road, the smell would dissipate.

I got into the DS quarter where the fuel separator lives and found what I think to be the source of these unpleasant odors!

I looked up this part on Spector and they are calling it the "Check Valve Tank" See #40 in diagram

You can see where it was cracked and clearly could vent vapors into the passenger compartment.

I chose to replace this cracked component with some 5/16 fuel hose and see how that works.

I have two questions:

1) How is this a check valve? To me it just looks like two small orifices at either end of the barrel.

and

2) What is the red dust in there? Is that normal accumulation from 34 years of fuel vapor?

LAMBCRUSHER · 09-10-09, 08:54 AM

P C
there is a check valve there. Looked like some kind of a cover in that pic for the valve. Also check for cracks on the casing of the seperator and hoses. I have a spare used (new in $or wrap) check valve. Pm me. Also, do you know the cond of your charcoal can? I get that un-used gas smell too, and have replaced the check valve and hoses on the vapor seperator. Starting to think it is a clogged canister. Side note- do you have the factory heat sheild/ cooling fan for the mani/carb? Mine dosen't and I seem to be loosing fuel from evaporation. I wonder if this is the cause or a contributor to my smell. Anymore insight on the vapor seperator would be cool.

eventhough · 09-10-09, 09:33 AM

I'm getting a gassy smell too and I think it has been tracked back to excessive tank pressure and a check valve that can't keep up. I just took out the check valve and once I get my new tank in I'll post up in my build thread the results.

PabloCruise · 09-10-09, 09:42 AM

Quote:

Originally Posted by LAMBCRUSHER

P C
there is a check valve there. Looked like some kind of a cover in that pic for the valve. Also check for cracks on the casing of the seperator and hoses. I have a spare used (new in $or wrap) check valve. Pm me. Also, do you know the cond of your charcoal can? I get that un-used gas smell too, and have replaced the check valve and hoses on the vapor seperator. Starting to think it is a clogged canister. Side note- do you have the factory heat sheild/ cooling fan for the mani/carb? Mine dosen't and I seem to be loosing fuel from evaporation. I wonder if this is the cause or a contributor to my smell. Anymore insight on the vapor seperator would be cool.

Thanks!

So you think I am missing the actual check valve in my pic?

My vapor separator *looked* o-k. I passed some low pressure (~10psi) air into it from where the check valve would connect and did not hear any hissing at the separator.

I also passed some 10 psi air into the line up to the charcoal cannister and encountered no resistance, so I think my charcoal can is doing o-k.

No heat sheild or carb cooling fan for me. I have swapped in a 3FE, so no carb either! Just a fuel rail running around 35 psi from an inline pump.

What other insight are you looking for on the vapor separator?

nuclearlemon · 09-10-09, 12:23 PM

is it stopped at idle, or running down the road?

PabloCruise · 09-10-09, 12:45 PM

Quote:

Originally Posted by nuclearlemon

is it stopped at idle, or running down the road?

Are you asking when do I get the smell?

I think it happened both at idle and running. Warm weather and less than full gas tank seemed to produce the smell.

Why do you ask?

(this is why I was wanting your vapor separator from your parted Pig!)

nuclearlemon · 09-10-09, 06:41 PM

Quote:

Originally Posted by PabloCruise

A
Why do you ask?

to see if it's an issue with the smell swirling in airflow, or to make sure the location was nailed down solid.

PabloCruise · 09-10-09, 09:23 PM

Got it. I'll be driving the Pig tomorrow, so I should be able to test for smell on the drive home...

LAMBCRUSHER · 09-10-09, 09:35 PM

Hi
yeah, I think there is supposed to be an actual whiteish plastic check valve. There was/is one in my pig, and I ordered one from $OR-I lied; it's not in a wrapper, but it does have the bar code/ label id'ing it as the fuel vapor seperator check valve. Both mine and theirs are identical. From your pic I couldn't see the valve, it looked like maybe a dust cover??? Blow through it one way, good flow; blow the other way, very restricted. Mine tested good, so I left it. Too bad I can't buy beer w/ the spare! I suppose the further 411 on the system would be more what I want; or just for that d### smell to go away! So I get my smell after driving for a bit in this mid cali summer sun. It's an unburnt fuel smell- not the notorios exhaust backswirl! I wonder, after I rr'ed all the hoses (except the BIG one to the tank), new clamps, tested vapor check valve and all new hose/ clamps, how to systematically diagnose each of the other comp's.(ie IS the seperator to blame?Charcoal filter?or is it that d### BIG hose?).

LAMBCRUSHER · 09-10-09, 09:43 PM

I must be blind!!!
That's no dust cover, that's a cracked open check valve in the color noir. That's what I get for replying to a thread I just picked up w/ the sleep still not rubbed out of my eyes! What I have look like what that one looked like when it was still in one piece- but white.

1973Guppie · 09-16-09, 11:25 PM

I had this happen in my 40, the systems are similar I am sure.

mine cracked, then I bought another, it cracked too, then I just put a piece of inline cut metal fuel line and made sure the venting was routed correctly to the charcoal canister. I am guessing your valve got clogged over time and brittle and cracked, same thing happened to mine. I have had no problems since and it has gotten rid of the gas smell. It makes sense that it happens on warm days with less fuel in the tank as I would guess the heat and the space in the tank allow for expansion.

Noah

PabloCruise · 09-17-09, 08:05 AM

Thanks Noah.

I wass wondering about the value of repalcing the check valve...

PabloCruise · 09-24-09, 12:11 PM

So far, so good, although the weather has been cooler lately.

I do notice that when I peak under the back of my Pig to check my pre-pump filter, I can smell gas under the Pig...

Anyone else notice that?

eventhough · 09-24-09, 12:34 PM

Quote:

Originally Posted by PabloCruise

So far, so good, although the weather has been cooler lately.

I do notice that when I peak under the back of my Pig to check my pre-pump filter, I can smell gas under the Pig...

Anyone else notice that?

I don't smell any gas under or near my Pig when its not running. I did replace the entire fuel system though from tank to carb. If it wasn't replaced it was rebuilt and I don't have any smog equipment including the check valve. I do have the fuel/vapor separator and it appeared to be in good shape.

My issues were when it was running I would get gas smell in the cab. After the fuel system rebuild/replacement it is much better but I still get some fumes. I think those are from my exhaust manifold leak that I am working on.

MiniPigg · 09-30-09, 08:29 AM

Those check valves are pretty common issue. Last one I messed with I cleaned and put back together and then glued and duct taped it... ya it didnt hold very well.. but i was poor at the time and it worked during winter but summer wasnt so lucky...

You might just replace all the rubber hoses. In the end that what I had to do. It was a fricken PITA!
And check the fuel separator for holes or cracks.