P171 and P304 codes showing up… what should I do?

Ford Issues Forum
1

I accidentally put about 2 gallons of contaminated gas into my tank, probably water, not sediments. The tank was more than 3/4 full at the time. I have a 2.3L engine with 93k miles, and it was running perfectly fine before this. Now, I’m getting P171 and P304 codes (system too lean on bank 1 and cylinder 4 misfire). The engine is running rough and it cuts in and out. I’m going to change the fuel filter this weekend, and I hope that fixes it. But the fuel pump swap looks like it’s going to be a pain in the neck!

2

It’s not too hard to get to the tank. The easiest way is to remove the bed, there are only 6 bolts, but you might want to have some spares on hand because they can get rusty. I snapped 4 of the 6 bolts when I did mine.

3

@Indigo
Thanks for the tip! I saw a video where someone did the fuel pump from underneath, and it looked like a major hassle. I’ll definitely try lifting the bed first!

4

I’d fix the misfire first. Once that’s done, the P0171 code will likely clear up on its own.

5

Here’s a step-by-step for dealing with that:

  1. Remove the bed.
  2. Remove the pump.
  3. Siphon out the bad gas and take it to a HAZMAT collection site.
  4. Cover the tank opening loosely to allow evaporation but keep any crud out.
  5. Remove the filter and let the lines drain until they stop.
  6. Once the tank is dry, check inside. If you see varnish deposits, wipe them out. (I think I used Simple Green, but I can’t remember.)
  7. Reinstall the pump and filter (either old or new).
  8. Add 2 gallons of ethanol-free gas or gas with stabilizer (in case it takes a while to fix the issue).
  9. Let it idle for 15 minutes.
  10. Shut it down, clear the codes, and let it idle for 15 more minutes.
  11. If the codes are still gone, go for a test drive (watch for cops, as the tail lights might be off). If the codes stay clear, you’re all set. Replace the bed and top off the tank with your preferred fuel.

If the codes come back, then something else might be wrong besides bad gas. Try this and let us know how it goes!

6

You might get lucky with PRI-G. I’ve seen it on YouTube do some amazing things with 3-year-old gas that had oil, water, and who knows what else in it, especially in lawnmowers. It’s said to be the only one that works.