Fuel vapour leak and P1456 code

ChrisD

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Am chasing a double problem with 1456 code and a fuel vapour leak. Have looked at several posts on this forum, which were useful but will need some more advice in order to get this fixed.

Vehicle is 1998 Accord LX with 2.3 VTEC.

The car leaks raw gasoline fumes but only after the car has been running. The smell comes from underneath the vehicle, about where the rear seat is. The fumes dissipate after 20-30 minutes which suggests that the buildup of pressure in the tank is what is leaking out. Once the pressure leaks out, the fumes stop.

Along with this, the 1456 code activates but it is intermittent. Once I delete the code, it could be 2 months before it lights up again. It's not constant.

In trying to remedy the 1456, these parts have been replaced:
gas cap, canister, bypass solenoid and two-way valve.

Have done a visual inspection on the tank and hoses, nothing obvious although not everything can be seen well.

Thinking this through, it seems like it can be one of two things.

One - there is a physcial break / hole in tank or hoses allowing the pressure to escape even though the EVAP system is functioning (no 1456 or 1457 most of the time).

Two - the pressure is not getting evacuated by the system. Since the 1456 is not always activated, it would seem that the pressure sensor is functioning. Since there is no 1457 code, it seems that the purge solenoid is also working. Also, if there is too much pressure in the tank, the gas cap is supposed to release it. The fumes are escaping from under the car, not the gas cap.

The other ingredient is the dreaded ORVR valve on top of the tank. Not sure how it works and if it has any influence on the flow of pressure from into the EVAP system. Found a post on this forum on how to get at it but don't want to tackle this if not necessary.

Grateful for any insights on this one.
 

coupe

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Mine is also emitting said fumes after driving the car for a while. There was some sort of purge valve that made noise for years when car was sitting and it doesn't make that noise anymore...anyone know which part it is which makes that noise?? I want to replace it first.
 

001Stunna

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Mine is also emitting said fumes after driving the car for a while. There was some sort of purge valve that made noise for years when car was sitting and it doesn't make that noise anymore...anyone know which part it is which makes that noise?? I want to replace it first.

If you're throwing a p1456 code try changing your shut off valve and retest. Sometimes changing the canister and valve will be more effective and easier.
 

ChrisD

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This problem is now fixed. Turns out it wasn't a fuel vapour leak after all. It was 10 years of Krown residue on the exhaust that was giving off fumes that smell exactly like gasoline. Believe it or not the Honda tech guy figured it out, I invested an hour of shop time to find out. Problem solved.
 

bwizard

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I've had the 1456 code lighting up my dash since I purchased the car in June. I tried the gas cap.....no luck. Tried the shut valve....no luck. Did a lot of searching and talked to a few good Honda mechanics and read and heard every possibility. So I decided to replace everything under there. I allready had the shut valve, so I ordered a new canister, a bypass valve, and the 2-way valve.

Today, I put the car on stands and crawled under there and got to work. My car is a Florida car, so no corrosion issues, thank goodness. I took off the canister and as I was removing the bypass valve and 2-way valve combo, I had some nasty smelling fuel empty out of the top of the 2-way valve as I flipped it around to disconnect the lines. I'm assuming my problem was the leak in the top of the 2 way valve as this should be a sealed system.


Old 2-way valve, you can notice some wetness on the top right.

ry%3D480


All the parts I replaced, less the canister itself.

ry%3D480


Hopefully I have gotten rid of the annoying CEL for good.:kenny:
 
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purpleaccord

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Wooow I got the problem lately....when my gas 1/4 tank left,my CEL is on, the code P1456. Blizzard let me know if what u change can fix the problem..
 

001Stunna

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Wooow I got the problem lately....when my gas 1/4 tank left,my CEL is on, the code P1456. Blizzard let me know if what u change can fix the problem..

You should start with changing the shutoff valve and vapor canister. For most people that solves the problem.
 
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