Problem diagnosis

[Smash_NDash]

Lately I have been lean surging REALLY bad in about the 2k-3.5k range while driving.


I have three check engine light codes:

12= power disconnected from ecu in last 50 cycles
31= Evap solenoid circuit
51= Lean fuel system


I know the 12 is appearing because my ecu seems to be crapping out, but what would be a cause of 31 & 51 appearing at the same time.

My guess is that when I got my car rebuilt it was sitting with about 1/8 tank of gas for about 6 months. I picked up the car in february 2012 and have been driving it ever since. Recently I have been driving my car all the way down to the E line on my fuel gauge. So I am assuming I have gotten a good bit of bad gas in my fuel system and my fuel filter might need a change.

My second guess would be an 02 sensor?

Third would be a bad MAP?

I have money to fix the problem, but I do not have money to just throw parts at it so any help on testing for specific problems would be greatly appreciated.

 

[3kgt2nv]

I know the 12 is appearing because my ecu seems to be crapping out

with this being said i would be hesitant to start trying to fix electrical issues. I would get a rebuild or a known good ecu and see how things go.

if the ecu capacitors are leaking it could short out all kinds of stuff and cause unknown issues to pop up.

 

[Smash_NDash]

I have and I still get the same cel codes

31 and 51 codes.

 

[Lou98GSX]

for code 31 you could have a bad purge solenoid . for code 51 you have to check fuel pressure also check for vacuum leaks .