tphan

For over 2 yrs under heavy boost/acceleration my 1994 have a strong distinct gas odor follow by a pssst sound. Some said FPD...other said leaky injectors or bad LIM gasket...but all doesn't add up until last Sunday when I was on my knees looking for the cell phone after a drive...gas odor was somewhere near the driverside rear wheel same location as the charcoal canister.

Today I extended the charcoal canister's 90* angle exhaust rubber hose into the cockpit and took the 7 out for a drive...as soon as the boost kick in I was completely stoned by the gas fumed and the psssst hissing sound was louder than ever...

Immediately pulled the car into a shopping center and repositioned the rubber hose outside under the car carriage...amazingly gas odor still present under heavy acceleration. The hose smelled like if it was soaked in gasoline after pulled car into the garage...

Conclusion: bad 1 way check valve between UIM and Purge Regular Solenoid.
Fix: Forget about removing the UIM to replace the valve
Work around: routes the rubber hose all the way to the rear of the car...away from the exhaust.

Now I can boost w/o worry about car fire...

TIA

DaleClark

iTrader: (55)

Very interesting! I may try and run a Viton check valve to replace that metal one for the charcoal canister system. The metal valves are usually pretty hardy, though.

Good find, and good experimentation to find the source of the problem!

Dale

tphan

is there any possibility of liquid fuel present in the canister? is it even possible? It is strange that the tip of the 90* rubber hose of the canister was kind shredded...weird (or it might just old 12 yrs).

tphan

well bad news...there is evidence of raw fuel in the rubber hose extending from the 90* rubber hose of the charcoal canister...

What exactly does the Catch Tank do?

TIA

DaleClark

iTrader: (55)

There shouldn't be liquid fuel in the charcoal canister. It's just for catching fumes from the gas tank, storing them to be later injected into the intake manifold to be burned by the motor.

Remember, federal emissions standards state that anything the car gives off has to be burned and processed by the catalytic converter. That's why the PCV system goes to the intake instead of atmosphere as well.

Time to hit the shop manual up. I believe there is also a check valve apparatus on top of the gas tank - something could be goofy there.

Dale

tphan

The hose now smell nothing...obviously, after sat overnight.

Sign of raw fuel completely throw off my theory...good to know gas odor wasn't from engine bay. I was about to put the car into shop to tear down the UIM...that would have been very costly.

I fully understood how the CC and evaporative system works...however not too sure exactly the function of the catch tank mount below the throttle body.

Next step is figuring a way collecting fuel to see how much got expelled under boost.

GustavOllufsen

The Catch tank is like an empty space in the pcv line. sometime slight traces of oil or other debris may be sucked thru the pcv system. The ctach tank is simple. think of it this way. an empty soup can(unopened of course) with a hose going into one side, and another hose coming out of the other side. if there is oil coming from the pcv it will fall down into the down into, while the air continues to move out of the can and to wherever the **** else it has to go.
________
| |
From Engine | |
>>>> ====== |. |======To intake or w/e to get recirculated
| . |
| . |
|__._____|

^^ Catch Tank

the dots in the tank is the oil falling into the tank while the air itself continues to move along its path.

Hope this helps to understand

GustavOllufsen

aw that turned out ****** gay
aw gd i worked so hard too thats so ****** lame

moconnor

iTrader: (14)

Yup - spaces are swallowed.

Here is a picture of the tank:

Jeff RX7

TPHAN, during the problem you describe, have notice excessive fuel consumption (around maybe 1 to 2 liters / 65 miles) ???

I've got a similar problem for one year with my 94 FD and I do not fix it yet. My car smell fuel under heavy acceleration, I don't see any fuel leak under hood, I replace fuel pressure dampner, O Ring, insulators, gromments ... for nothing.

Thanks for help

dgeesaman

iTrader: (7)

Replacing those parts is not a waste - you are now safe from failure in some very critical areas.

Dave

FJDRX7

iTrader: (32)

Thanks for the info, for a long time i was wondering what was that sound "psstt" and the fuel smell, now i know, Thanks

Jeff RX7

bump...

I noticed too that I have no more noise during open fuel tank... ???!!! is it normal... I remember a year ago, even 3 or 4 days after run, I heard pschhiiiiiiit when I open fuel tank cap...

ArmitageGVR4

iTrader: (13)

Any new updates/progress on this issue? I just determined yesterday my fuel smell is coming from the rear driver side wheel well. It seems intermittant -- it went away and then came back a month later in full force. I'm seeing 14-17 mpg average economy on a stock powered car which I assume is about right? The smell is very strong even when driving or standing still. It seems to come up through the trunk into the cabin as well as through the window when it's open. No fuel odor from the engine bay or anywhere up front.