Recently, I've been having some hard starts, loss of fuel pressure / performance under heavy acceleration and over 5000 RPM's, and a CEL (lean on bank one) code that turns off and on. My obvious thoughts were fuel filter, but since you can't just replace the fuel filter with the EP3's returnless system, I'd like to get some other opinions before buying an entire new fuel pump assembly. If I accelerate steadily, my A/F guage reads optimal until the very second I hit 5,000. The gauge immediately dips to lean, and I get a total loss of power / acceleration.

I was thinking about stopping by Auto Zone tomorrow before I fill up my gas tank and picking up some Fuel System cleaning additive. Any suggestions on a brand that you have good experience with?

Things I have tried: Replaced every single vacuum line in the engine bay, replaced my AEM dryflow air filter, checked all of the wiring connections and solders for the appropriate sensors, and hooked up an inline fuel pressure guage while starting, only for it to tell me what I basically already knew...low fuel pressure. Could use some input here

 

30 Views and no response, I know someone has had this problem before....

Added a bottle of Valvoline fuel system cleaner last night when I filled up, hopefully that will clear out any build up in the injectors / fuel lines if that's the problem. Will let you know how that goes.

 

Try either the Lucas oil Fuel additive or the Z-Max system cleaner.

 

Local auto parts store, or do I need to order it?

 

Your local auto parts store will have one if not both of those for sure. They're definitely worth the try even if it doesn't solve the problem.

 

Have gone through two tanks of gas now using fuel additive. No change whatsoever. I resoldered my o2 sensor wires near the ecu, as they seemed to be loose. I couldn't pull them out now if I wanted to, and the car runs "slightly" better. I only get loss of power at full throttle now. I also noticed that my AEM filter was pretty grungy, so I just completely pulled it off for a test run. Same thing.

Anyone have any idea at all? I've done absolutely everything but basically replacing the fuel system.

The error code I'm pulling off and on is a p0171, too lean. Light came on today for about two hours and I rushed to auto zone real quick.