Hyundai Repair: 2003 Elantra sometimes wont start, fuel pressure gauge, fuel pressure regulator

Question
QUESTION: My 2003 Elantra has 60,000 miles on it.  A couple of weeks ago I turned the key to start the car and even though it seemed that the engine was turning over, it wouldn't catch to start the car.  I kept turning the key and after a few tries the car finally started.  The car ran fine once it started.

Now this happens almost every day when I first get into my car, but once it's warmed up it works fine the rest of the day.  Every once in a while in the morning it will start but sputter out right away.  Twice it has started and seemed fine, but once I put it in drive and stepped on the gas, it stalled and I had to restart the car.

I brought it into an independent repair shop and they found nothing wrong when they ran the diagnostics test.  I also had the battery tested and it is good.  We also put STP full fuel cleaning system in my gas - the problem is still persisting.

Any idea as to what the problem could be???  I'm at a loss right now!

ANSWER: My primary guess is that you have a faulty fuel pressure regulator, allowing your fuel pressure to be bled off back into the fuel tank.  To verify this, a fuel pressure gauge will need to be attached to the vehicle and then monitored after the vehicle is turned off.  If the fuel pressure drops below about 20PSI while off immediately prior to the condition reoccurring, then you should expect the problem is with the fuel pressure regulator.

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QUESTION: Thanks for your help - I contacted the service department at the local dealership, and they said that the check engine light would be on if the fuel pressure regulator was the problem.  Do you have any other ideas?

Thanks for your help!

Answer
Unless the problem occurs while the car is running, the fuel pressure regulator cannot have any effect that will cause a check engine lamp.  Fuel pressure is not monitored by your ECM.  The dealer is either not interested in helping you or doesn't properly understand the how the fuel pressure regulator operates.

While the fuel pressure regulator isn't necessarily the issue, it is the primary suspect.  I'd recommend seeking assistance from a different dealer or from another shop with a good understanding of the operation of your fuel management system.