1998 Honda Accord LX 2.3L VTEC 228K miles
Things that I have ruled out as the cause:
Gas cap, fuel pump, fuel pump relay (already fixed it), ignition switch, key (to start), PCV valve, gas cap
Codes received:
P1456 - Evaporative Emissions Control (No gas cap before and it was running perfect! Then I bought a new gas cap, and it started doing this, I removed the gas cap, still does it, this is certainly not the issue)
P0300, P0301, P0302, 0303 - (cylinder misfire on each cylinder, DUH it's running rough, I can feel it!)
P1739 - Transmission code - common, ignore it this isn't the issue either
P1259 - VTEC System malfunction (also unrelated)

Okay here's why I am saying all this....
the car ran fine, ran strong, pulled strong, shifted perfect. You have to hold the ignition switch a little longer than I feel comfortable with for the engine to catch, the car always starts REALLY fast! usually in 1 second or less. If you let go IMMEDIATELY as the engine starts, it will die. However, if you hold it for 1 second more, the engine will stay on. This is not an exact science, just a quirk I learned about the car.
One day it wouldn't start, for several minutes my wife fought with it to get it started. She tried and tried, and nothing. Finally I kept coaching her over the phone what to do, to listen for the fuel pump and whether it was turning on or not. It was, but still wasn't starting. Finally out of nowhere, it started! Never had another issue for a week. Then yesterday, out of the blue, she started it up, as always started perfect, and she starts on her way to do her errands. PLOP! Car dies, no matter what, it won't start back up this time! Only I could get it started, that was only after hooking up my car to her battery and continuously cranking and cranking and cranking and priming the fuel pump listening for click on the relay. FINALLY it started!
Here's where it gets interesting.....
The car ran and idled fine. I let it warm up, and then pushed on the gas pedal, PLOP dies again. Hard as hell to get her started back up, eventually it starts back up.
Now, it idles fine, a little rough at times, but the ECU corrects it. A very soft and subtle touch on the accelerator she will rev all the way to red line, slowly but surely and no hiccups, no issues, no hesitation just revs and revs all day. HOWEVER, if I lunge the pedal as a hard rev, it will bog down and die! Now, keep in mind, when I get the car started, I can push on the accelerator slowly and rev it up to 1K rpms, and hold it there, and I can keep it running there with no issues whatsoever, annnd it will run all day long like that if I care to continuously hold the accelerator there. I can rev it higher and its smooth as butter! If I hard rev, it will die. It will start back up but it takes 5 or more tenacious starting attempts to do so. It starts up, idles very rough, shaking the car, idling like the old 80's land yachts that would continue running back in the day with carburetors in them. Remember when you shut the car off, but it still sputters and sputters and then eventually turned off? It was like that when idling after my battle was won to get it started again.
Now also take note that, it would do this for about 30 seconds, and then idle would level off and idle normally. Once normal idle kicked on, I gently press the accelerator and it revs for days! I hard rev, it dies! I let it idle it runs fine for several minutes, and then it may or may not die, depending on how it feels.
Here's a little extra for you extra Honda guys, are you able to recognize a Honda engine's distinctive sound when starting and the timing belt is off or out of time, or the balance shaft is off timing? Well, occassionally last night when trying to start I heard that EXACT sound! CPS? No, not likely, there are no codes and responds nothing like a bad CPS (Crank Position Sensor).

Now, what do you make of this and what are your thoughts on the cause?
What would cause this to happen so suddenly?

 

Suggest measuring fuel pressure. Low fuel pressure could cause hard starts, failure to start, and missing.

I had a weak fuel pump that would stick (no run) on a 94EX very intermittently. I had to rig a tell-tale wire to fuel pump power supply in the trunk w/ a light in the cabin. As long as light was On power was supplied to fuel pump. Finally caught the no-start when power was available, light on, but no fuel pump action. This would also cause a engine shut-off when decelerating very hard, but would start up after a long crank. In Houston traffic this was quite exciting

I also had a fuel pump w/ a faulty check valve that would cause hard starts unless I "primed" first w/ keyswitch to On.

Fuel trims can also catch a weak (low fuel pressure) condition. Long term and short term trims will be high (> 10% LTFT and possibly similar or higher STFT).

good luck

 

Thanks, my very first assumption was the fuel pump, 228K miles and a lot of abuse and neglect from the previous owner led me to this conclusion as well as the tell-tale signs of a failing fuel pump. What stumped me was the behavior of the pump. Why it would start and sputter and slow revs would work but hard and fast ones wouldn't. That's when all of it hit me, very low pressure then, consistent low pressure would allow it to run, but poorly. My mind: "well how is it able to run and rev all the way up, except when I rev hard?" I then realized that I am increasing the pressure gradually which the pump is still currently able to supply, but not enough to drive it (per se). Your comment and my original assumption led me right back to the pump.
Tonight I will be going to pick up a new fuel pump and, installing it into the car this evening. I will update the results after.

thanks!!

 

I hope it works out, but w/o testing this is not an assured fix.

See attached procedure.

good luck

 

Did the pump fix the issue because I am having the same problem...thanks!

 

I guess not...