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Check Engine Light is on... Gas Cap Problem


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#1 Lbifisherman429

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Posted March 16 2011 - 3:37 PM

My check engine light is on. I had it diagnosed to being a vapor leak so i bought a new gas cap and reset the light well the light has come on again and when i get out of the truck after driving it i can smell gas any ideas what this could be
Truck is an 01' Dakota Crew Cab 4.7 v8


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#2 RegDunlop

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Posted March 16 2011 - 4:11 PM

sounds like you have a leak somewher in the fuel line, or the fuel pressure regulator, ...did you try and get the code checked, it could be something more serious/complicated like a sensor going bad causing too much fuel to go in the mix and remain unburned, which could also possibly contaminate the engine oil and make it so thin it will no longer provide effective lubrication and cause the engine to seize..





If it is a newer ( post 96) vehicle go to autozone pepboys or advance auto and have them read the code ....its' free





also make sure the gas cap you bought is the right size, if you can get an OEM one


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#3 Lbifisherman429

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Posted March 16 2011 - 4:43 PM

sounds like you have a leak somewher in the fuel line, or the fuel pressure regulator, ...did you try and get the code checked, it could be something more serious/complicated like a sensor going bad causing too much fuel to go in the mix and remain unburned, which could also possibly contaminate the engine oil and make it so thin it will no longer provide effective lubrication and cause the engine to seize..

If it is a newer ( post 96) vehicle go to autozone pepboys or advance auto and have them read the code ....its' free

also make sure the gas cap you bought is the right size, if you can get an OEM one

had sears read the codes then went to autozone and they looked the truck up and got me the cap from the back


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#4 MoparCharlie

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Posted March 16 2011 - 5:36 PM

sounds like you have a leak somewher in the fuel line, or the fuel pressure regulator, ...did you try and get the code checked, it could be something more serious/complicated like a sensor going bad causing too much fuel to go in the mix and remain unburned, which could also possibly contaminate the engine oil and make it so thin it will no longer provide effective lubrication and cause the engine to seize..


If it is a newer ( post 96) vehicle go to autozone pepboys or advance auto and have them read the code ....its' free


also make sure the gas cap you bought is the right size, if you can get an OEM one


If it has an evaporitive emissions fault it will have nothing to do with the fuel supply so this info is not correct.

The common problems are as follows:

Sticky purge valve or leak detect pump. I doubt this is your problem because you smell gas,; the aformentioned problems usually do not emit vapors to the atmosphere, they go into the engine.

Gas cap, which you changed. As previusly mentioned make sure it is the correct cap.

More than likely you have a cracked hose or a cracked charcoal canister.
Been 4 wheeling lately or hit anything this winter?
Check the hoses from the tank to the charcoal canister and the lines from the canister to the purge valve.
I tend to think something is either broken/cracked because you can smell the vapor. Your nose should point you in the right direction.

Have you had a fuel pump,sending unit or fuel tank replaced lately? It possible that the seal for the fuel pump is no seated correctly, which usually causes a leak as soon as you fill up the tank (obvious gas on the ground).

Just so you know a little on WHEN this test runs:

The engine has to be cold ( coolant temp must be within 5 degrees of ambient temp )
Fuel must be betweeen 1/4 and 3/4
Vehicle must be running with no interuptions until the test is complete or it will not see the results as valid( 2 or 3 minutes ).

This info is good on Mopar vehicles until aprox 06/07 when they started to switch to the natural vacuum method of leak detection ( which takes place when the vehicle is sitting. Theroy being that as the car sits the fuel cools down creating a slight vacuum. This is what the computer looks for in a natural vacuum system )
Hope this helps.

If you find youself in North Jersey on a weekend shoot me a PM and maybe I can look at it for you.


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#5 Lbifisherman429

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Posted March 16 2011 - 5:53 PM

thanks.
I replaced the fuel pump in septemeber i will take a look at the feed lines


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#6 frankietool

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Posted March 16 2011 - 7:13 PM

I would lean more towards the charcoal canister. A saturated canister will give you a fuel smell especially when filling up.



You can also ask your mechanic if he has an EVAP system smoke diagnosis machine. This will detect any leaks and holes/cracks in the lines.


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#7 MoparCharlie

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Posted March 16 2011 - 9:13 PM

If you changed the fuel pump the fuel pump O ring may not be propperly seated. But by all means check the lines, if you left it off it would give you your symptoms.


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#8 Lbifisherman429

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Posted March 18 2011 - 5:17 AM

Codes Detected P0442 & P0455
What does that mean?
This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.
Symptoms
You likely won't notice any drivability problems.
Causes
A code P0442 most likely means one or more of the following has happened:


  • A loose or improperly affixed gas cap
  • A non-conforming gas cap (i.e. not factory/original brand)
  • A small leak/hole in a fuel vapor hose/tube
  • Other small leak in EVAP system
  • Faulty vent o-ring seal

What does that mean?
This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.
Symptoms
You likely won't notice any drivability problems.
Causes
A code p0455 most likely means one or more of the following has happened:

  • A loose or improperly affixed gas cap
  • A non-conforming gas cap (i.e. not factory/original brand)
  • Other leak or damaged piece in EVAP system
Possible Solutions
With a p0455, the most common repair is to:

  • Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
  • Otherwise, replace the gas cap, and/or
  • Inspect the EVAP system for cuts/holes in tubes/hoses (you may hear a vacuum noise or smell fuel), repair if necessary


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#9 MoparCharlie

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Posted March 18 2011 - 4:03 PM

Codes Detected P0442 & P0455
What does that mean?

This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.
Symptoms

You likely won't notice any drivability problems.
Causes

A code P0442 most likely means one or more of the following has happened:


  • A loose or improperly affixed gas cap
  • A non-conforming gas cap (i.e. not factory/original brand)
  • A small leak/hole in a fuel vapor hose/tube
  • Other small leak in EVAP system
  • Faulty vent o-ring seal
What does that mean?

This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.
Symptoms

You likely won't notice any drivability problems.
Causes

A code p0455 most likely means one or more of the following has happened:

  • A loose or improperly affixed gas cap
  • A non-conforming gas cap (i.e. not factory/original brand)
  • Other leak or damaged piece in EVAP system
Possible Solutions

With a p0455, the most common repair is to:

  • Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
  • Otherwise, replace the gas cap, and/or
  • Inspect the EVAP system for cuts/holes in tubes/hoses (you may hear a vacuum noise or smell fuel), repair if necessary


Sounds like they are confirming what I told you.

Driving the car for a day will NOT clear this type of code!!!
This is a one trip fail 3 trip reset, which means if it fails once the lite will go on and it needs 3 consecutive good trips to turn the lite out.

If you smell gas there is a vapor leak to find.

If you didn't smell gas I would steer you towards the leak detection pump.
Faulty ones have the switch stick which does not open the vent line which restricts purge flow.


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#10 Kicking Bass

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Posted March 21 2011 - 7:18 AM

I have a 02 dakota and had the same codes.I found 3 hoses with cracks. If you look under the hood, you'll find a sticker that shows the whole route of the evap system. Follow the all the hoses to the point of connection, this is where my hoses were all cracked. If you slide under your truck, beneath the driver's door towards the rear, you'll see a canister with 3 hoses connected to it, this was my reason for my codes. 2 of them were cracked pretty badly. You can buy the 3 hose kit directly from dodge, I think i might have a kit somewhere in my garage.-K


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#11 Lbifisherman429

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Posted March 22 2011 - 3:34 PM

I have a 02 dakota and had the same codes.I found 3 hoses with cracks. If you look under the hood, you'll find a sticker that shows the whole route of the evap system. Follow the all the hoses to the point of connection, this is where my hoses were all cracked. If you slide under your truck, beneath the driver's door towards the rear, you'll see a canister with 3 hoses connected to it, this was my reason for my codes. 2 of them were cracked pretty badly. You can buy the 3 hose kit directly from dodge, I think i might have a kit somewhere in my garage.-K

Thanks i will take a look


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#12 HeyDace

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Posted March 23 2011 - 7:28 AM

I'm thinking cracked hoses too. It seems to be a Chrysler thing.


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