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Old 08-27-2008, 06:13 PM   #1
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Question Help with P0440 and fuel system priming

My truck (2002 GMC Sierra 4x4 5.3) has had this issue in the past, and then it went away for a long time...now it's back. It throws a P0440 - Evaporative Emission Control System Malfunction, and seems to lose fuel pressure when it sits for awhile. When I go to start it, I can crank as long as I want and it won't fire unless I let it sit at "On" without cranking for a few seconds then crank it again.

The code and that symptom should not be together (evap is between the fuel pump and the gas cap, system pressure for immediate starting is between the fuel pump and the engine), but they are. When I get one, the other one happens soon; and if I lose one, the other one will go away soon.

I think it may be weather related, not happening when the temperature is generally high. It seems to come and go with the seasons.

The gas cap has been replaced with at least two different aftermarket caps. The fuel pump was replaced at least twice, maybe three times.

Why would that symptom and that code come together?
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Old 08-28-2008, 03:30 AM   #2
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on most vehicles, that code is because the gas cap was left lose. I have actually had to replace mine.

also, there is an evap box on most cars and a hose going to it. if there is even a pin size hole in that line or any of the rubber hosing then it could cause that light.

just a theory, in the summer time when it is hot, things tend to expand. if you have a pin size hole in one of those lines, during the summer it could be all but closed where as during the winter when the rubber draws up, it could cause you problems.

also, not sure where you are or the emissions testing there but that will cause you to fail inspection. at least around where I live
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Old 08-28-2008, 06:04 AM   #3
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I got lucky on the inspection issue...I just got it inspected and the light came on a week later. I'm good for two more years.

That theory is something I was considering, too, or similarly that the lubricant in one of the purge valves is thickening at lower temperatures and preventing it from operating properly. I'd hate to have to trace all those lines and try to detect leaks in them...
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Old 08-28-2008, 07:32 AM   #4
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one thing you could do is change out the readily accessible hoses first and see what happens. I would think that it isn't an actual gas line but the evap lines for the vapor. there is another code for a major leak which I would expect if one of your supply lines that actually held the liquid fuel had issues.

http://www.obd-codes.com/p0440

I am sure you probably know this but I figured I'd put a link.
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Old 08-28-2008, 07:54 AM   #5
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I had a gmc truck with a similar fuel pressure problem but with the 4.3 liter but they may share similar technology.

I bought it new and at around 150,000 miles the original fuel pump started acting up and I would turn the key to the "on" position for a couple of seconds and could hear the fuel pump power up and pressurize the system. Then it would immediately start. So then one day it just crapped out. I changed the pump. What a pia and I had to drop the tank and it was 3/4 full. So a while later with similar symptoms I couldn't figure out since I replaced the pump, I took it up the street to a real mechanic (I am not a real mechanic) and he replaced the fuel injector harness and injectors. It looked like an octapus (with plastic fuel lines and fuel injectors at the ends). There is a valve on the fuel rail and with the proper tool you can measure the fuel pressure. It should be holding 40-60 pounds pressure (if I remember right) or something is not right.

One thing about fuel pumps that are suspended in gas tanks is that they are actually cooled by the gas in the tank. So if you were to run it on 1/4 tank or less all the time, it could make the pump run hotter than it needs to and shorten it's life. I am not saying you are doing that but it happened to my Son after I gave him the truck and he replaced the pump AGAIN in it.

The evap system leak could be a purge valve intermittantly sticking. In which case you wouldn't see a bad line if they all look ok. Then after fifty or so engine start and stop cycles, the code will dissapear. Sounds like that is what possibly is happening. Finding a pin hole slow leak real pia - better a line should be visibly cracked or pulled off or something.

It is possible these 2 problems are a coincidence.

Sometimes a FSM is so handy with the diagnostic sections, but they are so pricey. I got the regular paper copy FSM on my jeep and my but is still sore. Maybe some where on line you could get a cd copy for yours.

I am not a professional mechanic, but am just relaying a similar problem in the hopes of helping you out.
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Old 08-28-2008, 08:28 AM   #6
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Quote:
Originally Posted by BEEF View Post
one thing you could do is change out the readily accessible hoses first and see what happens. I would think that it isn't an actual gas line but the evap lines for the vapor.
That would certainly explain the code, but it wouldn't explain the starting.

I had that link in my post already.

Quote:
Originally Posted by GasUser View Post
I bought it new and at around 150,000 miles the original fuel pump started acting up and I would turn the key to the "on" position for a couple of seconds and could hear the fuel pump power up and pressurize the system. Then it would immediately start. So then one day it just crapped out.
That describes my history pretty well, too. It was earlier than 150,000 miles when the pump died.

Quote:
I took it up the street to a real mechanic (I am not a real mechanic) and he replaced the fuel injector harness and injectors. It looked like an octapus (with plastic fuel lines and fuel injectors at the ends).


Quote:
There is a valve on the fuel rail and with the proper tool you can measure the fuel pressure. It should be holding 40-60 pounds pressure (if I remember right) or something is not right.
This is definitely something I need to check, since it's probably where my starting problem is.

Quote:
So if you were to run it on 1/4 tank or less all the time, it could make the pump run hotter than it needs to and shorten it's life.
I believe that was the cause of my first fuel pump's untimely death. Now I try to fill it at 50% every time.

Quote:
It is possible these 2 problems are a coincidence.
Possible, yes...but really strange that they ALWAYS accompany eachother. They've come and gone on their own, repeatedly, and always came/went together.

Quote:
Sometimes a FSM is so handy with the diagnostic sections, but they are so pricey. I got the regular paper copy FSM on my jeep and my but is still sore. Maybe some where on line you could get a cd copy for yours.
Flying Spaghetti Monster?


Okay, I know, a Factory Service Manual. You're right, they are definitely pricey. I've looked for them before.
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