Petrol Smell In The Cabin

Crosswind · May 25, 2015

Guys,

I have a couple of issues with the old banger (Mazda Familia BHALP)

1. There's a considerable smell of petrol in the cabin. I always run with the A/C on and on recirc mode. It seems to be more in the driver and front passenger area than the rear. There's no smell emanating from the petrol tank or the petrol cap. No injector leaks or leaks from the plugs. In fact, no smell from the engine bay at all. Its just inside the cabin. I did show the car to Mazna and he did sod all about it. What could be the cause?

2. There's a vibration in the car when stopped in D. Vibration reduces when shifted to P. Checked the mounts but the MOUNTS ARE OK. Injectors are ok. Car was tuned up recently. Mazna says it could be the distributor. Unfortunately, Mazna doesn't have distributors in stock so asked me to wait. Any other possibilities?

Thanks in advance.

Edited May 25, 2015 by Crosswind

Rumesh88 · May 25, 2015

Any chances of close encounters with rodent kind?

Crosswind · May 26, 2015

Quite possible but i havent inspected that closely. What do u think?

I can't confirm this one yet but it seems the petrol smell is coming from the A/C itself. I'll need to run the car without A/C for a while and confirm this.

Edited May 26, 2015 by Crosswind

Davy · May 26, 2015

Do you get the petrol smell when the car is stationary (in the morning before starting for example)? Or is it more prominent when the car is on the move? if it's the latter, then it might be that the firewall has a leak into the cabin - maybe due to a fallen rubber grommet or even a rodent as Rumesh has said.

I'm going to rule out transmission problems because you have said "reduces when shifted to P". How's your idle RPM when on P and D respectively?

Take a look under the back seat just to make sure your fuel pump is not leaking from the top gasket. Might be an answer to both problems.

Crosswind · May 26, 2015

Its not the stationary smell or the morning gas smell. Its while on the move. Smell gradually starts after driving for about 5-10 mins. Oddly enough, it seems to be more prominent when the A/C is on (although its on recirc mode). Transmission problems and engine mount problems can be ruled out because those were inspected. Idle RPM on P and D are about 700-900 range.

Kavvz · May 26, 2015

Crosswind said:
Guys,
I have a couple of issues with the old banger (Mazda Familia BHALP)

1. There's a considerable smell of petrol in the cabin. I always run with the A/C on and on recirc mode. It seems to be more in the driver and front passenger area than the rear. There's no smell emanating from the petrol tank or the petrol cap. No injector leaks or leaks from the plugs. In fact, no smell from the engine bay at all. Its just inside the cabin. I did show the car to Mazna and he did sod all about it. What could be the cause?

Crosswind said:
Its not the stationary smell or the morning gas smell. Its while on the move. Smell gradually starts after driving for about 5-10 mins. Oddly enough, it seems to be more prominent when the A/C is on (although its on recirc mode). Transmission problems and engine mount problems can be ruled out because those were inspected. Idle RPM on P and D are about 700-900 range.

Any chance the guys at Mazna didn't follow the fuel lines from the fuel tank all the way to the intake manifold while looking for leaks?

(Is it possible there may be some fuel leaking onto / leaking near the A/C unit thus stinking up the interior when you're driving / running the car with the A/C on?)

Edit:

Google Gods say to check:

1. The fuel pressure regulator. It's connected to a vacuum hose, and so are parts of your A/C system (Complete thread)

2. (Doesn't seem like its this, but its easy to check and rule out) Go under the back seat and open the fuel sending unit inspection panel.

3. (Probably not this as you only smell petrol when the car is running) Evaporative emissions canister / The charcoal canister

Edited May 26, 2015 by Kavvz

Davy · May 26, 2015

If there is a leak on the firewall, especially close to your blower motor chamber, then it's bound to pull in air from the outside. I'd start inspecting the grommets and rubber bushes in the firewall first. Check the grommet around the steering shaft, heater lines, wire harnesses etc. If everything seems to be sealed, then move on to the fresh air vent. Take off the wipers and the trim bits covering the motor chamber and check if you can spot a gap. Keep an eye for damage caused by rodents as well. If you can access the fresh air vent from outside, try pushing the flap to see if it looks like it leaks air into the car. The vent usually has a foam or sponge lining to seal against the body, rats love to tear this apart!

Your idle RPM seems to be normal. Did Mazna run a diagnostic scan before concluding that it is the distributor that is on it's way out? Check around the throttle body and intake manifold for disconnected or damaged vacuum lines.

NRX · May 26, 2015

On 5/26/2015 at 4:45 AM, Kavvz said:

Any chance the guys at Mazna didn't follow the fuel lines from the fuel tank all the way to the intake manifold while looking for leaks?

(Is it possible there may be some fuel leaking onto / leaking near the A/C unit thus stinking up the interior when you're driving / running the car with the A/C on?)

Edit:

Google Gods say to check:

1. The fuel pressure regulator. It's connected to a vacuum hose, and so are parts of your A/C system (Complete thread)

2. (Doesn't seem like its this, but its easy to check and rule out) Go under the back seat and open the fuel sending unit inspection panel.

3. (Probably not this as you only smell petrol when the car is running) Evaporative emissions canister / The charcoal canister

Huh. Did you notice the cause of that guys' (#1) issue ?

"It turned out to be a pinhole in a hose. Pretty simple fix."

Kavvz · May 26, 2015

On 5/26/2015 at 6:14 AM, NRX said:
Huh. Did you notice the cause of that guys' (#1) issue ?
"It turned out to be a pinhole in a hose. Pretty simple fix."

I guess deteriorating rubber is a pretty common problem as the cars get older?

Plus apparently mixing ethanol with refined fuel, while better for the environment apparently speeds up the deterioration of rubber. No idea i if a small percentage of ethanol is mixed into our fuels in Sri Lanka as well; does anyone know? (I checked the web but couldn't find any info on petrol composition and whether ethanol is added like it is overseas.)

trinity · June 4, 2015

Any updates on this?

aps · June 4, 2015

is ur brake booster leaking ?

Crosswind · June 4, 2015

actually no updates. I havent used this car in a few days and didn't actually have a chance to look in to this thoroughly.

I don't know the connection between the brake booster leaking and this problem but aps may have stumbled upon something. The brakes are not as good as they use to be. Classic symptoms of a vacuum leak is felt.

Davy · June 4, 2015

The only connection I see between the booster and petrol smell is that the booster is connected to the intake manifold through a vacuum line. Even if the booster is leaking, I don't see how petrol smell can come into the car, because the air flow is from the booster towards the intake manifold. Plus, most vehicles have a non return valve either in the booster or on the vacuum line to prevent the booster from losing vacuum. So it's unlikely that the vapour from the intake manifold reach the booster.

Also,this is an EFI engine, so the intake manifold will not contain a fuel rich air mixture, although it may have enough to give out a petrol smell.

Like I said before, check if vacuum lines are OK (including the booster vacuum line).

GayanR · June 8, 2015

Have you checked the fuel pump assembly hoses for any leaks(Under the seat).One of those gas exhausting pipes might have gone bad.

Luck · June 12, 2017

On 5/26/2015 at 1:34 AM, Davy said:

Do you get the petrol smell when the car is stationary (in the morning before starting for example)? Or is it more prominent when the car is on the move? if it's the latter, then it might be that the firewall has a leak into the cabin - maybe due to a fallen rubber grommet or even a rodent as Rumesh has said.

I'm going to rule out transmission problems because you have said "reduces when shifted to P". How's your idle RPM when on P and D respectively?

Take a look under the back seat just to make sure your fuel pump is not leaking from the top gasket. Might be an answer to both problems.

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Hi Davy if it is when car is in stationary(before starting),what's the matter? i'm in the situation like that

Davy · June 12, 2017

On 6/12/2017 at 5:53 AM, Luck said:

Hi Davy if it is when car is in stationary(before starting),what's the matter? i'm in the situation like that

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Could be due to a fuel leak somewhere. What's the car?

Luck · June 13, 2017

On 6/12/2017 at 7:52 AM, Davy said:

Could be due to a fuel leak somewhere. What's the car?

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Thank you Davy,

It's Peugeot 406 D8,1998 Brand new..

Maybe You'll correct, bcz fuel consumption is abnormally high and smtimes while the hill driving car loss accelatation..

Edited June 13, 2017 by Luck

Davy · June 13, 2017

On 6/13/2017 at 3:41 AM, Luck said:

Thank you Davy,

It's Peugeot 406 D8,1998 Brand new..

Maybe You'll correct, bcz fuel consumption is abnormally high and smtimes while the hill driving car loss accelatation..

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My first guess is that there's a small leak in the fuel pump gasket or one of the fuel lines is leaking fuel.

The fuel pump is located under the rear seat. There's probably a hatch that needs to be opened to access it. A simple visual inspection should reveal any leaks.

Luck · June 14, 2017

On 6/13/2017 at 8:52 AM, Davy said:

My first guess is that there's a small leak in the fuel pump gasket or one of the fuel lines is leaking fuel.

The fuel pump is located under the rear seat. There's probably a hatch that needs to be opened to access it. A simple visual inspection should reveal any leaks.

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Thanks Davy, I think I should contact my mechanic if so,and onething... Can empty or low fuel tank cause this consequence?

Davy · June 14, 2017

On 6/14/2017 at 3:47 AM, Luck said:

Thanks Davy, I think I should contact my mechanic if so,and onething... Can empty or low fuel tank cause this consequence?

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There shouldn't be any fuel smell inside the cabin regardless of how much fuel is left in the tank.

You should be able to easily removed the back seat and remove the hatch yourself to visually inspect if there's a leak. If you don't find anything, take the car to a mechanic for further inspection.

Jimmy · June 14, 2017

Before emptying the tank, like @Davy, I would suggest to check the petrol pump under the backseat for any leaks.

Luck · June 20, 2017

On 6/14/2017 at 10:15 AM, Davy said:

There shouldn't be any fuel smell inside the cabin regardless of how much fuel is left in the tank.

You should be able to easily removed the back seat and remove the hatch yourself to visually inspect if there's a leak. If you don't find anything, take the car to a mechanic for further inspection.

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Thanks davy...and also thanks to God, now there is no any petrol smell in the cabin after I filled fuel (bcz the fuel warning light on in that situation) but I think it is must to check fuel pump as soon as possible as you suggest..at least repair my fuel gauge.bcz it is wrong..

Luck · June 20, 2017

On 6/14/2017 at 10:36 AM, Jimmy said:

Before emptying the tank, like @Davy, I would suggest to check the petrol pump under the backseat for any leaks.

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Thanks Jimmy...and also thanks to God, now there is no any petrol smell in the cabin after I filled fuel (bcz the fuel warning light on in that situation) but I think it is must to check fuel pump as soon as possible as you suggest..at least repair my fuel gauge.bcz it is wrong..