Been seeing a p1440 code and tried all the possible fixes. Bought a new OEM gas cap but no dice. Dealer wants $700 to diagnose and fix the issue, but being a 99 Max I don't see a justification for it.

Wondering if its possible to wire a resistor to the EVAP Pressure sensor?

 

The fuel system operates with a slight vacuum to suck the gas fumes out of the fuel tank and and burn them in the engine. The P1440 code is saying that vacuum pressure cannot be created. The service manual lists 22 possible causes and that does not include things such as the fuel filler neck being rusted out.

I don't know how or where the ECU monitors the vacuum. Hopefully someone else does.

 

Its the evap purge control valve, thats the code I had when mine went bad. Heres a picture of it.

 

thanks but I thought the evap purge control valve would have another code. Afraid to start changing this and that, but turns out its not the issue and dealer would still charge another arm and leg to fix it.

 

Go on ebay and buy one and if its not the problem you can return it. There cheap as 28.00 dollars. Here the link http://www.ebay.com/itm/95-96-97-98-...tSYMoI&vxp=mtr And you get to return it back with in 30 days.

 

Theres a step by step procedure to diagnose the evap system. Search for it before replacing parts that are not bad. Will save you some money.

 

did some more research seems like for a 1999 EPA allows two 'not ready' codes in the computer. So my plan is to drive the car until its less than 35% fuel, so the EVAP system will never be 'ready'

 

You can service or at least clean the evap purge control valve. I'd suggest doing that at the least and see if it yields any positive results. If you find any charcoal bits in it then you are on the right track.

 

This worked, and was able to pass inspection with EVAP not ready. Could have had one more "not ready" and still passed, since its a 1999 vehicle.