Fuel smell in car turned into foul smell

JAVIERR

MEMBER
2013 MAZDA
15,000 MILES

My vehicle listed above is a CX9. First owner of car, only 15,000 miles.
Drove in late mid-June 2013 from Portland (OR) to Yosemite (CA). During the first 8 days of the road trip no problem going up and down the mountains (highest at 7,000 feet).
On day 9 driving leaving Reno (NV) on the steep highway a strong fresh gasoline smell start coming into the car. Not sure if through the vents or from the outside since windows were rolled-down (too hot outside). We were not using the A/C.
The fresh gasoline odor persisted during a couple of miles. Stopped to check. Open the hood and the smell was coming from the front somewhere in there.
The smell became intermittent but slowly changed from fresh gasoline to just really bad smell. Also its intensity decreased but was still very noticeable. Made it to Portland (OR) alive. Dealer has not checked it yet but already claimed over the phone it is normal. I do not understand how such a strong smell of fresh gasoline and hours of lingering foul smell can be normal. I am 51 years old and have been driving for many years around high and low country on very long road trips. No car ever did this to me. Even went to the Canadian Rockies! That is as high or more than Yosemite or Reno! Therefore, how can such a discomfort and toxic exposure be normal?
Please en-light me.

3 Replies

CADIEMAN

MECHANIC
3,544 POSTS

The car needs to be checked! Take it to the dealer it is not normal.

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Monday, June 24th, 2013 AT 7:21 PM

JAVIERR

MEMBER
2 POSTS

Hello, Thank you for your reply. Just came back from the dealer. As usual, they found nothing. However, I drove it with one of the mechanics and the bad smell I mentioned in my previous e-mail came-up. I stopped the car, left the engine running and he inspected it. He went down to smell the exhaust and the foul smell is coming from the exhaust. The dealer’s explanation is a bad grade gasoline I filled-up with at an ARCO station in Reno.
Apparently Mazda is aware of the foul smell happening and it has a bulletin out called "Sulfur Smell From Exhaust System" that applies to Mazda -2, Mazda-5, CX-7 and CX-9. Mazda's recommendation is to change the brand of fuel and to drive the vehicle for 100 miles. That should decrease the sulfur smell. Mazda also recommends to avoid short trips and aggressive acceleration. All three recommendations sound to me like "the car is bad". The car can only use expensive gas, the car should be preferably used on highway (which we were doing when the problem started), and if a bear (or out of control vehicle) is running behind you do not accelerate too quickly to avoid the smell. All sounds pretty bad to me: “use your car only for display, the smell will go away”!
Okay, change the brand of gas: we refueled at Shell in Southern Oregon after using the ARCO gas down to the empty and drove about 150 miles. The skunk smell is still intermittent as noticed this morning by the mechanic.
Okay, avoid driving short distance (do not use your car, use your bicycle): the problem started on highway and remained on highway for 12 hours, and continues in city.
Okay, do not accelerate all of the sudden: no bears yet or road hazards have forced us yet to do so.

Finally I used my car last night for a 1.5 mile drive. Left it in the garage overnight as usual. At 2 AM went to the bathroom and the foul smell was inside the house.

I almost went to the DEQ station with the secret hope to have my car impounded for hazardous emissions and therefore, force Mazda to react. However, I will try once more to let the gas go to empty and refuel again with the Top Tier gasoline and see what happens.

Would you have any other ideas?

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Tuesday, June 25th, 2013 AT 12:33 PM

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

I read your post and have an idea as to what may be happening. The first thing is the original fuel smell followed by the sulfur odor.

The smell of rotten eggs can be due to a compound called hydrogen sulfide. It can be in the fuel. However, other things can cause it as well. An internally damaged catalytic converter, an engine that is running too hot, or a fuel pressure regulator which has failed allowing too much fuel to enter the combustion chamber.

Since you smelled fuel, I would start with checking fuel pressure. If the regulator is bad allowing pressure to rise above the manufacturer's specs, it will cause the fuel mixture to be too rich. As a result, you can get this type of smell. We have two ways that can be checked.

First, if you have a live data scanner, examine the short term fuel trims. They should be around 0. If they are in the higher negative numbers, that indicates the computer is trying to lean the mixture and could be an indicator of high fuel pressure.

Second, check fuel pressure and regulator. Here is a link that shows how to test fuel pressure in general:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

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Here are the directions specific to your vehicle for testing. The attached pics correlate with the directions. Additionally, pressure specifications are included in the directions.

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2013 Mazda Truck CX-9 AWD V6-3.7L
Fuel Line Pressure Inspection
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Testing and Inspection Component Tests and General Diagnostics Fuel Line Pressure Inspection
FUEL LINE PRESSURE INSPECTION
FUEL LINE PRESSURE INSPECTION [MZI-3.7]

WARNING:
- Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death. Fuel can also irritate skin and eyes. To prevent this, always complete the "BEFORE REPAIR PROCEDURE".

1. Complete the "BEFORE SERVICE PRECAUTION". See: Fuel Pressure > Component Tests and General Diagnostics > Before Service Precaution

2. Disconnect the negative battery cable. See: Battery > Removal and Replacement > Battery Removal/Installation

3. Remove the engine cover. See: Engine > Removal and Replacement > Engine Cover Removal/Installation

4. Perform the work using the following procedure.

- Set the air cleaner cover aside.
- Disconnect the quick release connector from the fuel distributor. See: Fuel Line Coupler > Removal and Replacement > Quick Release Connector Removal/Installation
- Connect the thin part of SST (49 T013 102) to SST (49 N013 102A) until a click sound is heard.

pic 1

- Connect the thick end of SST (49 T013 102) to the quick release connector until a click sound is heard.
- Connect SST (49 B019 901B) to SST (49 N013 101A).
- Connect SST (49 N013 101A) to SST (49 N013 102A) until a click sound is heard.
- Turn the SST lever so that it is 90° to the hose as shown in the figure.

5. Verify that the selector is in N or P position.

6. Start the fuel pump using the following procedure.

Using M-MDS
- Connect the negative battery cable. See: Battery > Removal and Replacement > Battery Removal/Installation
- Connect the M-MDS to the DLC-2.

pic 2

- Using the simulation function "FP", start the fuel pump. See: Computers and Control Systems > Reading and Clearing Diagnostic Trouble Codes > On-Board Diagnostic Test

Without using M-MDS
- Remove the fuel pump relay.

pic 3

CAUTION:
- Short the specified terminals because shorting the wrong terminal of the main fuse block may cause malfunctions.

- Using a jumper wire, short fuel pump relay terminals C and D in the main fuse block.

pic 4

- Connect the negative battery cable and operate the fuel pump. See: Battery > Removal and Replacement > Battery Removal/Installation

7. Measure the fuel line pressure. (during key on engine off (KOEO))

- If not as specified, inspect the following:

Zero or low
- FP circuit
- FP
- Fuel line (clogging)
- Fuel leakage inside pressure regulator

High
- Pressure regulator

Fuel line pressure
- 375-450 kPa [3.83-4.58 kgf/cm2, 54.4-65.2 psi]

8. Stop the fuel pump using the following procedure.

Using M-MDS
- Stop the fuel pump using the "FP" simulation function. See: Computers and Control Systems > Reading and Clearing Diagnostic Trouble Codes > On-Board Diagnostic Test

Without using M-MDS
- Switch the ignition to off.
- Disconnect the negative battery cable to stop the fuel pump. See: Battery > Removal and Replacement > Battery Removal/Installation

9. Complete the "BEFORE SERVICE PRECAUTION". See: Fuel Pressure > Component Tests and General Diagnostics > Before Service Precaution

10. Disconnect the fuel pressure gauge and connect the fuel pipe.

11. Complete the "AFTER SERVICE PRECAUTION". See: Fuel Pressure > Component Tests and General Diagnostics > After Service Precaution

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Because you started with a fuel smell that led to this rotten egg smell, this is where I would recommend starting. Do this and let me know what you find.

Take care and let me know if you have other questions.

Joe

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