I have a weird problem, my sister improperly stored a 2000 4 cylinder Honda Accord for about 8 years. She started driving it about 8 months back.

The CEL came one, cand gave codes 300-304 and P1399. Took it to a mechanic, we replaced the wire set, spark plugs, distributor cap, and rotor. Fuel pump cost a total of $700

The problem went away for about 5 days, but now it's back. Any idea what else it could be? Ran a fuel injector cleaner, but made no difference. Now the mechanic is saying we may need to change the fuel injectors or gas tank since there might be debris in the tank that keeps clogging the fuel injectors.

 

First step is to stop taking the car to that mechanic. Spark plugs don't go bad from sitting, nor do caps rotors or wires. Fuel pumps won't go bad either.

If there is questions about debris in the tank, remove the fuel sending unit and look. See for yourself. This could save a TON of money.

How long after starting the car did the code appear? Is there a drivability symptom along with the codes? Can you tell the car is misifiring?

 

When the problem first showed up, we could easily tell it was misfiring. Now that the light is back onreally can't tell, but the accleration is terrible. How hard is it to remove the fuel sending unit? I know very little about cars. The light came on after 5 days or about 80 miles

 

try adjusting the valves... that's what i did and it goes away, i already put 2000 miles on it and it passed the smog, by the way my 01 accord has 320,000 miles on it.