Code?

[movin2stereo]

I have a code PO440,evaporative emission control system malfunction.What causes this one?

[blazee]

Most common cause is a loose gas cap.

[movin2stereo]

Forgot to mention,I just changed the fuel pump.Would this have anything to do with it?BTW,it's a 98 with a 4.3.

[blazee]

Yes, did you reconnect the vent hose to the top of the tank?

[blazee]

To test for leaks the evap system pulls a vacuum on the tank and monitors how fast it loses the vacuum. A p0440 means that it wasn't able to pull a vacuum on the tank. This is mainly caused by a large leak.

[movin2stereo]

Originally Posted by blazee

Yes, did you reconnect the vent hose to the top of the tank?

I took the bed off.I didn't pull a vent hose just the lines that went to the sending unit.Is it possible that the sending unit isn't sealed to the tank?What esle could leak,the lines?

[blazee]

Anything that would allow gas vapors to escape from the tank could be the problem. The enitre fuel system is supposed to be sealed. It could be the gas cap, fill hose, vent hose, the hoses going to the vapor canister, a hole in the tank.....maybe you didn't seal the tank good when you replaced the pump. A leak in the Evap system is one of the hardest problems to fix, even using special equipment. Since you didn't have problems before you replaced the pump, you should start with the parts of the system that you encountered.

[blazee]

I found an awesome 95 page Adobe Acrobat pdf file, that covered every aspect of the EVAP system. It showed all the different types of systems, how every component worked....everything. But one of my spyware programs deleted my list of recently visited web pages and now I can't find it. If anyone reading this has a few minutes, please try a search for it and if you find it, post a link.

[movin2stereo]

Well,I deleted the codes yesterday and put 60 miles on it and I have been checking the codes and nothing is coming up now.So thanks for letting me what the code was and now I have a good idea where to look first.