Two weeks ago I fixed a faulty fuel pressure regulator. The diaphram was failing. I tested with a pressure gauge from O'Reilly, according to the Honda FSM tests. It failed. Replaced it.

And then for two weeks almost everything has been normal, but slightly longer starter motor turning before it fires-up. Suddenly today, the car sputters as it runs sometimes. On my Ultra Gauge, the short term fuel trim leans-out steadily. And will settle at something like -28% fuel trim, though it might also move back toward the normal values. Does this all the time suddenly. Go into neutral and has stalled three times today. Stalling events sometimes are preceded by an idle speed that is unsteady. The one thing that never returned quite to normal after replacing the fuel pressure regulator was the starting cycle, which required slightly longer cranking almost every time. Pre-priming the fuel pressure with the key sometimes seemed to solve the problem. I have been meaning to look into it, but there are always a few things with this car, and I gotta live and work too. Haha!

Back to testing...

Any ideas as to what to test?

Thanks!

 

Faulty fuel injectors intermittently leaking unmetered fuel into the engine, then at other times cutting off completely, stalling the engine?

 

hi I went thru the same problem one time it was a leaking injector. put some new ones and problem should be fixed

 

Did you use a stock regulator and hook up the vacuum hose? Do not use adjustable regulators on a stock setup.

The -28% is way out of where it should be trimming to. That means the ECU is fighting off a major oversupply of fuel.

Pull the spark plugs and inspect them, if one is all black that means too much gas in that cylinder, likely a bad injector.

The pump has a check valve to prevent the gas from running out of the line and back into the tank, which makes it hard to start next time. The fuel pressure should stay up for a while after stopping the engine.