How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Steve Your Own Question

Steve
Steve, Auto Service Technician
Category: Car
Satisfied Customers: 5494
Experience:  25+ yrs experience as a professional working technician; ASE L1 master technician
Type Your Car Question Here...
Steve is online now
A new question is answered every 9 seconds

I have a 2002 cadillac escalade. The service engine ...

Customer Question

I have a 2002 cadillac escalade. The service engine soon light came on.THE past owners said they replaced fuel pump.I stoped at autozone,has code PO440-(evap-evaporative emission system small leak/ no flow cond.) I changed fuel cap.The fuel tank has a small leak under tank.Do you think loose line or fuel pressure problem.Runs like ruff idle. can you help with some advice to fix?THANKS
Submitted: 6 years ago.
Category: Car
Expert:  Steve replied 6 years ago.

Hello!

The P0440 code indicates that the vehicle ran a leak test on the evaporative emission system (which includes the fuel tank) and it failed the self test.

Periodically when the engine is running, the computer will seal off the fuel tank and evap system by commanding the solenoids in the system closed, and then open one to allow engine vacuum to draw a vacuum on the system. It is then resealed, and the computer uses a pressure sensor mounted on the top of the fuel tank to monitor for vacuum decay. If the system cannot maintain vacuum during the test, a fault code is stored to indicate a leak is present and the light is turned on. This self test is capable of detecting pinhole leaks equivalent to a .001 inch diameter hole; it is extremely sensitive.

Since you know a fuel leak is present, that is likely why the test failed; the leak will need to be identified and repaired before the system will ever be able to maintain a vacuum. Not being able to see your car, I cannot tell you the exact point your fuel leak is coming from; you will need to drop the fuel tank and visually check to identify the leak point. Being that someone recently had the fuel pump module out to replace the pump, the most likely point that a fuel leak can occur would be at the rubber seal where the module is sealed to the top of the tank. It only takes one very tiny speck of dirt in between these parts to cause it to not seal properly...

Hope this is helpful!

Steve, Auto Service Technician
Category: Car
Satisfied Customers: 5494
Experience: 25+ yrs experience as a professional working technician; ASE L1 master technician
Steve and 4 other Car Specialists are ready to help you
Customer: replied 6 years ago.
The tank is full now.Will it hurt the truck to drive it for a couple of days'Just until the tank is empty,so i can drop the tank to check rubber seal on top of tank.I don"t want to risk any major damage to engine etc.
Expert:  Steve replied 6 years ago.

The code you ahve stored is an evaporative system (emissions related) code. You will not damage anything by driving the vehicle untill the tank is almost empty before attempting repairs.

The only concern would be the fuel leak; if it is coming from teh top of the tank area it should stop leaking when the level drops slightly. If it is a leaking fuel line connection, it may continue to leak. A fuel leak is always a safety or fire hazard for obvious reasons.... you may want to monitor the leak to make sure it stops after a while before deciding when to correct the problem.

Customer: replied 6 years ago.
Thanks alot STEVE

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • The nearest Volvo dealer is 160 miles away. Best $15 bucks I have spent in a long time! Paul M Corpus Christi, TX
 
 
 

Meet The Experts:

 
 
 
  • Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
< Last | Next >
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris (aka-Moose)'s Avatar

    Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
  • http://ww2.justanswer.com/uploads/TE/TedG/2012-6-15_14759_avaLarge.64x64.jpg Ted G.'s Avatar

    Ted G.

    ASE Certified Technician

    Satisfied Customers:

    1596
    20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness
  • http://ww2.justanswer.com/uploads/joecamel90/2008-11-13_03615_head_shot.jpg George H.'s Avatar

    George H.

    ASE Certified Technician

    Satisfied Customers:

    1311
    ASE Master Tech 15+ yrs, AAS Automotive Technology, Factory trained Asian specialist
  • http://ww2.justanswer.com/uploads/AM/amedee/2013-10-24_23656_Amedee1.64x64.jpg Amedee's Avatar

    Amedee

    ASE Master Tech

    Satisfied Customers:

    2367
    ASE Master Tech advanced level specialist
  • http://ww2.justanswer.com/uploads/SU/supermechanic/2013-8-23_03546_500.64x64.jpg Jerry's Avatar

    Jerry

    Master Mechanic

    Satisfied Customers:

    1906
    ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager
  • http://ww2.justanswer.com/uploads/CR/crzydrvr00/2013-11-3_12123_246347.64x64.jpg Richard's Avatar

    Richard

    ASE Certified Technician

    Satisfied Customers:

    942
    12 years Ford Lincoln/Mercury Jaguar dealership as a technician and shop foreman reparing all makes
  • http://ww2.justanswer.com/uploads/ST/Steve7654/2012-6-5_215929_japic800x660.64x64.jpg Steve's Avatar

    Steve

    Auto Service Technician

    Satisfied Customers:

    1980
    25+ yrs experience as a professional working technician; ASE L1 master technician