P0172 Code- Help Please
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Joined: 01-23-2009
Posts: 26,485
From: Fredericksburg,VA
How have you checked the vapor pipe? Vapor does not cause puddles or drips.
When the purge valve opens vapor from the tank is drawn into the intake manifold. If there is a leak in the line (connection or corrosion) unmetered air is sucked in instead of fuel vapor. That will also cause the tank to not retain pressure.
When the purge valve opens vapor from the tank is drawn into the intake manifold. If there is a leak in the line (connection or corrosion) unmetered air is sucked in instead of fuel vapor. That will also cause the tank to not retain pressure.
Thread Starter
Senior Member
Joined: 12-10-2010
Posts: 131
From: Collinsville, IL
How have you checked the vapor pipe? Vapor does not cause puddles or drips.
When the purge valve opens vapor from the tank is drawn into the intake manifold. If there is a leak in the line (connection or corrosion) unmetered air is sucked in instead of fuel vapor. That will also cause the tank to not retain pressure.
When the purge valve opens vapor from the tank is drawn into the intake manifold. If there is a leak in the line (connection or corrosion) unmetered air is sucked in instead of fuel vapor. That will also cause the tank to not retain pressure.
Tomorrow I'm going to hook up the fuel pressure gauge and see if I can get some baseline readings, and let it set for 15 min.
Please keep in mind, once the car is started and ran.... There is no issue restarting the car. Only time there is an issue starting the car, is after it has sat for multiple hours.
I did go ahead and order fuel injectors and a new fuel pump to have on standby.
Thread Starter
Senior Member
Joined: 12-10-2010
Posts: 131
From: Collinsville, IL
Administrator
Joined: 10-13-2011
Posts: 39,993
From: Welland,Ont Canada
It’s been known to happen, the fuel lines rust out in pairs.
The pressure line is easy to spot the leak, but the vapour line, usually rots out , undetected, under the insulation shield .
this as Donbrew pointed out allows for the fuel tank to not hold pressure and that causes a longer start up.
So, drop the tank, replace the fuel pump, the lines are much easier to clamp into place with the fuel tank out of the way.
similar symptoms as mine, I replaced fuel pump first, then injectors, then the two fuel lines, problem solved.
The pressure line is easy to spot the leak, but the vapour line, usually rots out , undetected, under the insulation shield .
this as Donbrew pointed out allows for the fuel tank to not hold pressure and that causes a longer start up.
So, drop the tank, replace the fuel pump, the lines are much easier to clamp into place with the fuel tank out of the way.
similar symptoms as mine, I replaced fuel pump first, then injectors, then the two fuel lines, problem solved.
Moderator
Joined: 01-23-2009
Posts: 26,485
From: Fredericksburg,VA
OK, I thought it was obvious in my explanation above.
P0172 means there is unmetered air getting into the combustion chamber.
Hard start because when you start an engine usually it wants extra gas, not extra air. That is case #1. There is air instead of gas vapor going into the intake.
Case #2 is there is no fuel in the "on deck" circle, so it takes time to get to the injectors. Air is is venting from the tank, allowing the fuel to back down past the check valve, because a vacuum is being created.
P0172 + hard start = EVAP leak somewhere. The EVAP system includes the entire fuel tank and pump.
There is a remote possibility the #1 O2 sensor is malfunctioning to cause the P0172 alone.
P0172 means there is unmetered air getting into the combustion chamber.
Hard start because when you start an engine usually it wants extra gas, not extra air. That is case #1. There is air instead of gas vapor going into the intake.
Case #2 is there is no fuel in the "on deck" circle, so it takes time to get to the injectors. Air is is venting from the tank, allowing the fuel to back down past the check valve, because a vacuum is being created.
P0172 + hard start = EVAP leak somewhere. The EVAP system includes the entire fuel tank and pump.
There is a remote possibility the #1 O2 sensor is malfunctioning to cause the P0172 alone.
Thread Starter
Senior Member
Joined: 12-10-2010
Posts: 131
From: Collinsville, IL
OK, I thought it was obvious in my explanation above.
P0172 means there is unmetered air getting into the combustion chamber.
Hard start because when you start an engine usually it wants extra gas, not extra air. That is case #1. There is air instead of gas vapor going into the intake.
Case #2 is there is no fuel in the "on deck" circle, so it takes time to get to the injectors. Air is is venting from the tank, allowing the fuel to back down past the check valve, because a vacuum is being created.
P0172 + hard start = EVAP leak somewhere. The EVAP system includes the entire fuel tank and pump.
There is a remote possibility the #1 O2 sensor is malfunctioning to cause the P0172 alone.
P0172 means there is unmetered air getting into the combustion chamber.
Hard start because when you start an engine usually it wants extra gas, not extra air. That is case #1. There is air instead of gas vapor going into the intake.
Case #2 is there is no fuel in the "on deck" circle, so it takes time to get to the injectors. Air is is venting from the tank, allowing the fuel to back down past the check valve, because a vacuum is being created.
P0172 + hard start = EVAP leak somewhere. The EVAP system includes the entire fuel tank and pump.
There is a remote possibility the #1 O2 sensor is malfunctioning to cause the P0172 alone.
I've already replaced the 02 sensor and checked for exhaust leaks.
Again. Car has something like 78k on it. 2009 2.4
I've got a new fuel pump and injectors en route. I'll replace the evap line and fuel pump.
But first, I'll post my Fuel Pressure readings before doing anything.
I appreciate all your guys help. Just trying to keep my wife from being stranded.