buschman

I was upgrading my fuel system in the Hawk and now I'm getting P0440 codes. All my evap lines are hooked up properly that i can see. the things i noticed were there;

* I had my throttle body re-powder coated and the guys coated over the Evap nipple. So i had to sand down the powder to get the evap hose back on properly.

* I'm still using the stock tank. But I removed the stock supply line in place of an -8AN steel braided line. i then moved over the old stock supply hose over to the return nipple. Well those plastic snap on hoses are very rigid and basically I'm crossing one that was molded to go to the left of the evap line to now having it going to the right. I'm wondering if it's crimping it off somehow.

* Occationally when I get on it I smell ma hit of gas inside the car(I cut the hole in the body over the tank). And it's not like a certain level of throttle. Sometimes a WOT blast will do it and sometimes it won't. Sometimes a 50% throttle blast will do it and sometimes it won't. maybe i just don't smell it all the time, but when it hits, you can REALLY smell that gas.

* I did lower compression Heads and Cam at the same time as the fuel upgrades. I got **** poor gas milleage my first tank, but now it's actually getting back closer to normal. Not sure if this has anything to do with it.

How can I test to find out where the problem is? I'm having no issues filling up the gas tank(indicating that the EVAP system is working to some degree).

Thanks in advance,
Mike

wrencher

iTrader: (2)

The evap system has a leak. It will fill no problem with a leak. But when the system closes up the purge flow & the vent solenoid, the gas tank & the charcoal canister cannot hold a vacuum. This is measured by the fuel tank pressure sensor. So either the pressure sensor is faulty, or you do have a system leak. If you can smell fuel that pretty much leans to the later as the cause. An evap system leak can be a real bitch to find sometimes. I know us mech-in-neck's use evap tester's & special smoke machines = $$$$ So the diagnostic bill for finding such a problem will reflect this.

buschman

Thanks for the heads up. When my gas gets low I might drop the tank partially to see what might be going on up there. I really think the way my old supply line(now a return line) and evap line are crossed over each other is the problem.

I'll report back what I find.

Mike

wrencher

iTrader: (2)

One other thing do not over pressurize the system for testing purposes. The fuel tank pressure sensor is very sensitive & can be destroyed with more than a few psi or HG" of vacuum applied to it.

buschman

The pressure tester being that light blue cylinder on the end of the EVAP line inside the tank? If that's true what's the larger black cylinder that mounts nect to the drivers side fuel rail up near the throttle body.

Mike

02BlueFirehawk

on the rail is the evap cylinder. the rectangle sensor on top of the tank is the one he's describing I think? Same type sensor that does MAP.... the round thinger for the return line is a regulator I believe.

buschman

Well Rob, you and I pulled your tank didn't we? I know I helped pull someone's 99+ tank and theirs has a canister molded into the tank, that looks like a one gallon gas tank. I thought that was the evap canister?

Still confused where the sensor is...

Mike

02BlueFirehawk

Bob and I dropped the tank the first time; We just cut a hole and pulled the top out. I had already taken out the in-tank regulator... I know the rectangle is the pressure sensor because I broke the nipple off mine when futzing around with it to get it off.... had to buy a new one which is the same sensor ID number that measures pressure at the manifold. There's like something mounted on the front-top-outside of the gas tank... but can't recall...I thought it was sqwarish.

wrencher

iTrader: (2)

All those descriptions sound correct. But your problem does sound more like a leak in the system. Do you have a scanning program? Can you get the FTP (fuel tank pressure) PID? Take the gas cap off key on does it read 0? If so you likely have a good FTP sensor.Well at least a correctly calibrated to center one (0) The PCM test the system by putting it under a vacuum, & then watching the FTP sensor for it's output. If it decays at to fast of a rate , that indicates an evap system leak. The PCM flags a P0440 DTC.
Finding the leak is the fun part.

buschman

Rob, Now I know what you're talking about. Thanks for the clarification.

Wrencher, The only scanning program I have is ATAP. Can I assume that it is not able to measure FTP? If so let me know. If not, then no I don't have the scanning software.

Is this the type thing when I could pressurize the gas tank and listen for a leak? I thought the evap system was open to the intake manifold? If that were true how would you ever pressurize the system?

Mike

wrencher

iTrader: (2)

I dont know if ATAP includes the FTP pid or not.The pressure testing part is the hard part, the FTP works off a low pressures.
It is generally 2 psi to 2hg" of vacuum. To much can cause the FTP sensor to get ruined from the overpressurization.
Like I said hard to find & big $$$ equipment involved for testing.
The purge flow solenoid controls manifold vacuum to the canister. The vent control solenoid opens to allow fresh air in for purging. These are all controlled by the PCM. Evap system testing is not a simple endeavour. Each system has slight variances but to test a F car you need to close the vent solenoid, & pressurize the system. Usually a smoke machine is utilized here.( it fills the gas tank & canister with a correct low pressure smoke) I dont thing this is one you can do in the garage.
If you where able to remove the FTP sensor & close the vent solenoid off to the charcoal canister, you could prolly pressurize it to see if you can find a leak. Do overpressurize it , you can easily create more leaks. It is not designed for alot of pressure.