passenger gas tank....

[bojangles]

My car is a 95 S4s. kept immacualtely in California.. Hardly any evidence of even use in the rain. The quarter windows are sealed perfectly...
I have taken everything hose related apart obove the passenger tank and changes a few things that looked old. The vent hose included. I have been sniffing until I am light headed and it really seems like the smell is coming from the tank area not the charcoal canister in the engien compartment,,, But this is a bit hard to tell.

UNder the car I can see the bottom of the tank and the foam and it looks as new as can be, I cant get my hand in there to touch it tho cause of the sump part of the tank.. The driver side is perfect and the foam is dry and perfect...

So what is the advice? should I pull the tank? looks like a pain in the arse to do that.. I still have to drive a bit more to get the tanks empty.. but the wheels are off for straightnening and the rotors for skiming.. and the chargecooler pump is apart.. and and and and....

I just want to drive with the window down without gas smell...
Bruce

[cnh1990]

On the passengers (right)side in USA fed cars there are 2 hoses from the charcoal canister that ends up in the fuel tank area under the carpeted tank covers. To access this area the tank cover under the (right) rear quarter window must be taken off by unscrewing numerous small black phillips head screws held in place by tinnerman clips.

Once the cover is off you can see the vent hoses. From what I recall (it has been a while since I last did this) one goes to a fitting (a "T" with perhaps a reducer) on the filler neck and the other to a one way fresh air intake check valve held in place by two large phillips head bolts that can be seen on the surface of the (right) hatch gutter just opposite of the fuel filler flap. The check valve is mounted inbetween the the gutter and the fuel filler flap. If you ever remove the check valve or hoses do not drop small parts or items inside the tank compartment and they will be there forever. Some people have dropped screws, washers, fasteners, etc..

If the hoses have ruptured, the check valve failed, or the connector/reducer has cracked and fallen apart you will get a fuel smell in the passenger tank area. It is made of the same materials as the over the rear window fuel balancer hoses that is so common to fail in our cars.

Good luck,
Calvin

>> Edited by cnh1990 on Friday 16th April 16:48

[bojangles]

yes I have had all that apart - I have even dropped some screws down there... And i did get them out using a magnet and coathanger... I even found the missing bolt to attach the ECU properly so it does not rattle anymore..

The second hose is ok, the teeeny hose to the BARO sensor is ok.. ( although I found the elbow at the engine end was cracked, along with outer vacuum elbows too.)

I just find it hard to believe that the tank is rusted... it looks so perfect no matter where i look.

Well if it is not better when the car runs next I will have no choice but to pull the tank.. is this procedure posted anywhere?

[cnh1990]

Is possible that the tank has been overfilled and raw gas been introduced into the canister?

Could a high spped turn with a full tank cause fuel to migrate up the filler neck to cansiter hose and then end up in canister?

Is the canister to the engine vac intake check valve working? It is located near the fuel rail at the front of the engine near the cam belt.

[bojangles]

if the canister had to much liquid gas in it or the check valve was leaking - where would your nose detect the smell?
the canister is way under the coolant bottle and I have peered down there and touched the hoses, but I dont smell much in that area... I guess I need to pull it out and take a look.. can I clean up the inside of the canister ( blow compressed air for a while? )


How can I tell if the tank is rotten?.... you cant access the foam from under the car on the RHS


Bruce

[cnh1990]

If the cannister had gas in it or if the check valve failed it would barf up into the compartment just to the inside of the right fuel filler flap.

[bojangles]

There is a hose from the canister to the air cleaner housing and another that goes through a "roll-over" valve ( not one way but if the car rolls it blocks) and then to a second hose connection on the gas tank filler neck. There is no place where gas can spill even if cornering like a bastard...
BRuce

[superdave]

Iam no expert buy depending on which model you have, there is a return pipe going back to the top of your tank. This carries excess unburnt fuel back to your tank. If this pipe is cracked then you'll get the smell you describe under hard acceleration.
I have a 1990 UK carb turbo but this return pipe goes back to the driver's side tank.
The other thing to consider is how full is your tank under normal conditions? If you only run say half full, then you tank could corrode over a period of years slightly above this line. When you fill the tank higher then you smell the leak.
Finally, you need to get the undertray off and check the connection to the underside of the tank and also the hose connecting to your driver's side.

Cheers,



Dave Walters

[cnh1990]

The gas will sometimes under certain hard cornering conditions go up the filler pipe and overflow into the canister if the check valve near the cam belt fails it can blow air back into the canister and out the fresh air intake in the (right) side tank well. Some engines fires have been reported when the canister has been saturated with fuel. Larry Marsala claims he has seen this happen on an Esprit on the track in the SF area. I'm not sure but I think Guy Theriens is rebuilding one of these cars damaged in this way.

>> Edited by cnh1990 on Friday 16th April 16:47

[bojangles]

I think what you are calling the fresh air vent is really the vapor escape that should be going through a hole in the side of the air box in the RHS tank area. If yours is venting to that area it should be routed throught the hole in the air box so any vapour is burned.

[cnh1990]

There is a fresh air canister intake in the tank well area and if the check valve near the cam belt/thermostat area (this is also the hose one splices the BOV vac trigger hose) fails it can barf up fumes into the right tank well area. I know this area well as I have replaced the canister hoses.

Edited to change from left to right.

>> Edited by cnh1990 on Friday 16th April 16:46

[bojangles]

We gotta get thing straight here I always say Right side and you always left..
I am 200 km away from my car this week and i cant check what you are saying...
I stil think the hose you are talking about should go in to your air box... there are 3 clear hoses under that carpeted cover...
one is the big connection between the 2 tanks filler neck to filler neck
one is a smaller one that runs from the engine compartment to the air box,
the third is one goes fron the tank filler neck to the canister through the roll over valve..

I will take a good look again tomorrow night when I see the car... but I am 99.9% sure there is no hose that just ends in the RHS Tank area( = passenger side LHD car )

Bruce

[cnh1990]

So sorry I wrote it down wrong. I will correct the past posting to make sense. It is the Right side we are talking about. Passengers side USA fed car. Sometimes i get confused and inver the right and left because of when chatting to our UK owners.

>> Edited by cnh1990 on Friday 16th April 16:50