Chasing 0455 Code 2007 Suburban 5.3 flex. help!

Eric Birney · October 9, 2019

Hello, I am hoping someone can help. I have had 0455 fuel leak code for months. System has been smoked. Purge valve was replaced. Vent valve has been replaced twice, new Evap Canister, New gas cap. Tank was even dropped the last time. usually a few days after leaving the shop the light is back on. Anyone have any ideas? Truck is an 07 Suburban with 5.3 Flex motor.

swathdiver · October 10, 2019

18 hours ago, Eric Birney said:

Hello, I am hoping someone can help. I have had 0455 fuel leak code for months. System has been smoked. Purge valve was replaced. Vent valve has been replaced twice, new Evap Canister, New gas cap. Tank was even dropped the last time. usually a few days after leaving the shop the light is back on. Anyone have any ideas? Truck is an 07 Suburban with 5.3 Flex motor.

Ensure that all parts replaced were GM OE or ACDelco Professional. There is a condition where a leak can exist while the system is under vacuum. This can be tested by a bi-directional scan tool like the Tech-2 which will use the Purge/Seal function to look for a leak. This is a large leak, I suspect the smoke test was not done right/thoroughly. You still have the filler neck, Fuel Tank Pressure Sensor and some more lines that go around the gas tank that could be leaking or their connectors. This stuff is a pain, I've been chasing a small leak for months but am going to buy a smoke machine to finally get after it.

Eric Birney · October 10, 2019

7 hours ago, swathdiver said:

Ensure that all parts replaced were GM OE or ACDelco Professional. There is a condition where a leak can exist while the system is under vacuum. This can be tested by a bi-directional scan tool like the Tech-2 which will use the Purge/Seal function to look for a leak. This is a large leak, I suspect the smoke test was not done right/thoroughly. You still have the filler neck, Fuel Tank Pressure Sensor and some more lines that go around the gas tank that could be leaking or their connectors. This stuff is a pain, I've been chasing a small leak for months but am going to buy a smoke machine to finally get after it.

That's what I was afraid of. This has already been an expensive endeavor. I would have sold the truck if it had not been my Dads.

swathdiver · October 10, 2019

51 minutes ago, Eric Birney said:

That's what I was afraid of. This has already been an expensive endeavor. I would have sold the truck if it had not been my Dads.

Replacing everything, the shotgun approach, costs about $500. You've already done much of it and if the condition of the truck is nice, they are nice to drive and make memories with.

Are you in Florida by chance?

Eric Birney · October 10, 2019

1 hour ago, swathdiver said:

Replacing everything, the shotgun approach, costs about $500. You've already done much of it and if the condition of the truck is nice, they are nice to drive and make memories with.

Are you in Florida by chance?

No, I wish. Nebraska. The truck is in great shape and only has 130k for being 12+ years old.

swathdiver · October 10, 2019

58 minutes ago, Eric Birney said:

No, I wish. Nebraska. The truck is in great shape and only has 130k for being 12+ years old.

Ok, too far to use mine. Replace the rest of the parts or take it to a dealership with a good reputation and have them put their big smoke machine on it.

Eric Birney · October 21, 2019

Ok, shop had the truck all last week. Reputable friend of the family place. Had on smoke machine for more than an hour and did not see any leaks except at gas cap. This is the 3rd gas cap I have put on and it never feels like it snugs well even after 3-4 clicks. Drove to KC and no issues, go up next day to go to airport and CEL light pops on again. If it is the fuel tank pressure sensor will you see smoke? Fuel pump is only 2 years old but recently the gas gauge has been a bit off. When truck is completely full, it does not register full. if i park on an incline it takes forever to level out and show me the actual level.

swathdiver · October 22, 2019

8 hours ago, Eric Birney said:

Ok, shop had the truck all last week. Reputable friend of the family place. Had on smoke machine for more than an hour and did not see any leaks except at gas cap. This is the 3rd gas cap I have put on and it never feels like it snugs well even after 3-4 clicks. Drove to KC and no issues, go up next day to go to airport and CEL light pops on again. If it is the fuel tank pressure sensor will you see smoke? Fuel pump is only 2 years old but recently the gas gauge has been a bit off. When truck is completely full, it does not register full. if i park on an incline it takes forever to level out and show me the actual level.

I bought a new cap and sent it back, made the code come back quicker. Maybe your filler neck is worn, not allowing the cap to seal? Don't know the answer to your question about the FTPS.

riverbanks · October 22, 2019

Sand the filler pipe smooth and vasoline oring on cap and pray, stubborn truck,I would have taken the same path as you,and99% of the time,done,over,po455 definition ,besides large leak is "unable to reach calibrated vacuum level",ftps,is it lying?

Eric Birney · October 23, 2019

On 10/22/2019 at 12:32 AM, swathdiver said:

I bought a new cap and sent it back, made the code come back quicker. Maybe your filler neck is worn, not allowing the cap to seal? Don't know the answer to your question about the FTPS.

I will give this a shot. The issue I am running into for the 07's is there are 3 different OEM gas caps listed. Some "vented" and some not. Going to try a different cap as well.

riverbanks · October 23, 2019

Are you shopping online? haven't heard of a vented one at Auto parts store, just curious

Eric Birney · October 23, 2019

I ordered one from Rock Auto at first, and there are like 4 different Delco options and then the repair shop ordered me a yellow one for E85 truck, which mine is, but he says description says vented.At this point i feel like I am chasing a ghost. I will try and lightly sand and vaseline as well