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Fuel Smell Troubleshooting

6K views 11 replies 4 participants last post by  CB700S 
#1 ·
Since shortly after we got this 94 Fleetwood, we've had some fuel smell issues.

First, we had a fuel smell in the cabin pretty much all the time, but not outside the car. This was most evident during colder weather and was present from engine start. The fuel pressure regulator was checked and we found fuel residue and a smell of fuel in the vacuum hose going to the regulator. I replaced the fuel pressure regulator with a new Delphi unit and the problem went away.

Once the weather started warming up, we've noticed another fuel smell issue. On warmer days, there is occasionally a fuel smell again coming from the air conditioning system. It only seems to occur if the car has just come to a stop or turns a corner. This time, you can smell it outside the car around the passenger front side. It dissipates within half a minute or so. Fuel economy may be down a bit (not entirely sure), but power seems fine.

We recently discovered some rodent damage to the area around the purge valve that I posted about earlier.





I'm going to be repairing that this weekend, based on information I found in the archives, but I wanted to sanity check this and make sure I'm not missing any common troubleshooting or fix steps. Alternately, does this sound like I'm on the right track?

Things we've done:
- The fuel pressure regulator has been checked, no leaks or smell of gas there.
- Checked the gas tank - hoses on top still seem to be intact and connected.
- Gas tank seems to be mildly pressurized when the cap is removed on a warmer day - there is an outflow of vapor (not an inflow) for between 3 and 15 seconds when removing the cap.
- Examined the engine bay evaporative emissions hoses and noted they're disintegrating and seem like they might be porous.

It seemed to us that the fuel smell was related to fuel tank pressure spiking when the fuel in the tank was significantly agitate which increased vapor pressure. Between that and the gnawed nipple and maybe the hose that vents to atmosphere, that could account for the fuel smell.

Things we plan to do:
- Replace the purge valve and Rochester valve/vacuum valve with new Delphi parts. (We found them on sale at Amazon and Rock Auto for stupid cheap when we were looking for something else.)
- Replace that gnawed nipple with some emissions hose as noted here.
- Replace the canister hoses with new emissions hose as listed here.
- Replace the original gas cap with a new one.

Am I forgetting any potential causes of the fuel smell in this area? Does this seem like a rational conclusion or course of action? Thanks in advance.
 
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#2 ·
Repairing the wiring and going through all the hoses will put you a good deal ahead. The only thing I think of aside from your rundown is that hose coupling joining the tank with the EVAP run back to the front. The one that's always rotted, looks like mice ate it, or just plain missing. I replaced that piece on 2 Fleetwoods. You may have already covered this in your description, and may not apply anyway if there's pos pressure already.

IDK why I did it, but 1/2 recall rebuilding a charcoal can 10 years ago on a Fleetwood for some reason.
 
#3 ·
The fuel tank must not have pressure POSITIVE pressure. the tank most times will have when engine is running a slight vacuum / sucking on fuel cap removal.

so with pressure in tank this maybe [for me] the hoses at around the charcoal canister required replacing since they collapsed and prevented fuel vapor pressure to enter the canister. what also could be a failure is the canister is bad from liquid fuel entering it. this causes the canister to plug up. now with rodents chewing the canister purge hoses and components this will cause fuel vapors in the vehicle under hood and HVAC venting because the air intake is at the windshield area and down low under the hood on the passenger side .. hard to see but it is sucking air from that location. under the evaporator drain hose area. I actually put in some rat wire to keep the rodents from entering the blower venting section down there.
 
#8 · (Edited)
Just a finding with a engine bay fuel smell + drive-ability problems. I traced it to the fuel test port Schrader valve, Ya you can replace it like a tire valve and its NOT cheap. I guess the valve fails with 20 years of use and allows some fuel to escape and fill the plastic cap. This also cause the fuel pressure to LEAK DOWN and it was hard to start. I don't know how much pressure it was loosing, you would not be able to tell anyway with a gauge hooked up to it but... They do leak! If the leak got bad enough and the cap seal failed to seal, oh yea fire! It did not take long for the cap get get wet.... If I removed the cap after I turned off the car I could hear fuel escaping like a nail in a tire.

ACDELCO 12570619

Oh, You may also want to service/ inspect all the fuel injector I o-rings too. A few of them looked meh when I took the fuel rail off but I reused them... I had no new ones on hand. You can have the smallest fuel leak that does not even leak any liquid fuel , it evaporates before you see it and still have a fuel smell
 
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