Need some help 2010 4.6 Long Crank on startup

[SoCal_Karma]

Hello Gents,

Today after my sons football game we jumped in the car to head home. I pushed my start button and the engine just kept cranking without firing. After about 7-8 seconds of not firing I hit the button to stop it. I waited a few seconds and tried again, same result.
Finally I just let it keep cranking and it started after about 10-12 seconds. All the way home (35miles) it was running rough and I could definitely tell the power was just not there.

Got everyone home, shut it down. I waited 2-3 minutes hit the start button and it fired on the first crank, drove around the block and it felt fine. Weird?
This is the second time the Long Crank symptom has happened in the last 60 days.

Note.. It was over a 100 degrees today.
Have had a recent tune-up and am at 120k miles.

Any insight or guidance would be appreciated. Hopefully its just a fluke and not a tell-tale of something failing.

Cheers

 

[EdP]

Hello Gents,

Today after my sons football game we jumped in the car to head home. I pushed my start button and the engine just kept cranking without firing. After about 7-8 seconds of not firing I hit the button to stop it. I waited a few seconds and tried again, same result.
Finally I just let it keep cranking and it started after about 10-12 seconds. All the way home (35miles) it was running rough and I could definitely tell the power was just not there.

Got everyone home, shut it down. I waited 2-3 minutes hit the start button and it fired on the first crank, drove around the block and it felt fine. Weird?
This is the second time the Long Crank symptom has happened in the last 60 days.

Note.. It was over a 100 degrees today.
Have had a recent tune-up and am at 120k miles.

Any insight or guidance would be appreciated. Hopefully its just a fluke and not a tell-tale of something failing.

Cheers

What was done at this "tune up"? New spark plugs? Fuel filter?
It always comes down to the three things needed for ignition, fuel, air, spark. A code reader may tell you something. Now it may have been perfect when in for service, but one of those is not as good now. Given the temperature, fuel may have been a problem. You don't hear about is much these days with fuel injection, but vapor lock used to be an issue in heat. If your fuel system is wearing that could be a cause.

 

[homeofstone]

I agree with above re code reader. Also, if the fuel filter and fuel tank air filter have not been changed then change them since its way over due for a 2010.

 

[eric.nielsen]

I have this same problem intermittently. It started a few weeks ago & I'm guessing it's related to vapor in the lines. I will look at getting my fuel filter and tank filters replaced. It's never a cold engine problem, only happens restarting a hot engine (and it's summer now).

BTW a similar thing happened with the Hyundai XG350 I had prior to this car. Again, only in the summer when restarting a hot engine. That same car needed the fuel tank filters replaced as it would kick off every gas station's pump from too much back pressure.

If anyone knows why these would happen after a 'long start' please let me know (2012 Genesis sedan 4.6): rough, rushed shifting; no daytime running lamps; high engine idle speed, Check Engine light comes on for duration of that trip. Thanks

 

[SoCal_Karma]

Greetings Gentlemen,

Thank you for the guidance.

Here's an update...
Had the Fuel Filter and tank air filter replaced this week. Had another hot day today and had the long crank symptom happen again which makes me believe that it is some sort of "vapor lock" or heat soak issue. Looking back this only started happening this summer, and its been a real scorcher.

I came across this purge valve. Anyone think this could be a contributor?



Also found this on the Gen Coupe forum

 

[homeofstone]

Purge valve caused a bogging down on my daughter's Santa Fe but not a starting problem. Have you has the codes read on the car?

 

[SoCal_Karma]

Gentlemen,

I have an update and info from my Hyundai dealership.

I ended up taking the car in because the "long crank" was getting worse.

Here's what I learned (some of you may already know this). The dealer says the fuel pump does not turn on until the engine is started (push button start models). There is some sort of diaphragm or check-valve in the fuel pump that is designed to keep fuel pressure at the rail when the engine is off.
When this starts failing, fuel ends up draining back to the tank, causing long starts and potential misfires, kicking it into "limp home mode"

They tested this by putting a gauge on the rail and watched after the engine was shut off. Within 15 minutes there was 0 pressure at the rail.

New fuel pump fixed the problem. Also as a bonus (since I still have a warranty) I mentioned that I was starting to feel it "bump" back into first when coming to a stop. They diagnosed that I needed a new tranny. Didn't get a new one but got a certified rebuilt one.

All said and done, I'm a happy camper.

Cheers

 

[eric.nielsen]

For my 2012 sedan 4.6 liter long start, the problem turned out to be the crankshaft position sensor. Parts & labor came to $195, have had zero problems since. Near as I can tell, heat had something to do with the unreliable sensor's performance - hotter part, worse performance.

While they had the car I had them replace the front brake discs and pad, as well as all new brake fluid. The rear brakes were fine. All were original to the 2012 build. Goes to show that using the appropriate gear to descend (I live in the mountains of North Carolina) really helps.