Code 43 - Check process

[Shrewz92]

91 EX, 178,000 on odo, auto trans. Check engine OBD blinks code '43' when jumped at ECU. Most sites say that's a fuel system related problem (is 'delivery' meant by that?). History: I did tune up in March 05: replaced cap/rotor/plugs/7mm plug wires/air filter/fuel filter all at one swat. (Didn't touch timing, as I am unfamiliar with how and I don't have the equipment.) It was 2nd replacement of plugs since I bought the vehicle in 2003. Plug wires looked to be originals. Drove approx 1,000 miles and CEL came on. Owners Manual said was emissions related. Honda dealer said was O2 sensor. I replaced with a new aftermarket Bosch O2 sensor. Drove 200 miles and light on again. Took to repair shop, they said O2 sensor was ok. On drive away from shop, Accord would bog-down. I'd let off the accelerator, punch it again, and no issues. Took back to shop and they disconnected the O2 sensor: ran like a scalded dog, after that. However, to be sure I didn't have a possibly defective O2 sensor, I replaced with another new Bosch O2. To reset the whole she-bang, I disconnected the neg battery cable to reset ECU. Problem still occurs: I can drive approx 29 miles after each CEL occurrence and reset. After re-set, the CEL comes on, again after about 29 miles of driving. I do the ECU jump and count the flashes: Still code 43. What could I be missing? Could this be an issue with Fuel Pump/Fuel Filter? Where should I start checking the Fuel Sytem Related parts of the code 43? Checking pressure of fuel pump? Checking the fuel lines @ the filter? Checking the vacuum hoses coming off the manifold? Beuller...?Beuller...?

[AccordCodger]

That was rather long, so maybe I missed it. Did you check the gas filler cap? It's sealed, and that's part of the system.

[Shrewz92]

Thanks for the reply. No, sir, the gas cap WASN'T in the original post. However, I've seen no cracks in the top , and the rubber in the seam still seems ok. However#2: I don't hear the WHOOSH that accompanied opening up the filler cap, as I did when I had my 91 Civic EX. That may be an issue. Thank you AUTOCODGER for another direction in which to look.

[Shrewz92]

Excuse me. Thank you 'ACCORDCODGER.'

[Shrewz92]

Situation So Far:
Replaced Gas Cap as AccordCodger suggested, and replaced O2 sensor with Denso/Honda OEM piece as suggested by my garage, purchased from PartsAmerica.com @ $108.96, no shipping, no tax. 2k miles on new O2 sensor, feels like more power, too.

[Igovert500]

From what I found, code 43 could be: Fuel supply system circuit OR fuel supply system...not sure which. Regardless, if this new o2 sensor doesn't fix the problem, I'd start checking out:

1. The fuel pressure
2. The fuel pressure regulator
3. Vacuum leaks