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Alright boys and girls, here's the deal. Starting about a year ago, if she sits for between 3 and 5 hours, Emma will sometimes crank and stumble and fail to turn over OR will turn over after a prolonged, gasping and lumpy crank. This is now becoming much more frequent and I'm worried that the day is fast approaching where she won't start at all.

Initially I thought the battery was dying so I replaced the battery and the problem went away for about a week. When it returned, I figured the spark plugs were going bad so when I got closer to 100k, I put in new spark plugs (last week). This too solved the problem for about 48 hours and now it's back and quickly getting MUCH worse. It used to happen once every other week or so and now it's doing it almost daily. I've never bothered taking it in because it trips no codes and is so random even I have trouble guessing when it will happen.

No codes or pending codes are stored and this has not once tripped the check engine light. What's weird is that if it adamantly refuses to turn over or the starter motor times out after ten seconds, I can shut her off and push the start button again immediately and she'll fire up like it never happened. I'll say this...warmer weather definitely makes it worse.

I'm leaning towards the coil packs as they're original but I'm also fearful that the lack of a check engine light means this could be an ECU slowly failing and going insane. Any other ideas?
 

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dunno about your car specifics, but fuel has to stay in the rail to feed the injectors. there is a valve, anti drainback, when the system is shut off, this valve will prevent all the fuel from draining from the rail. when the car sits for a long time, if the valve is bad, fuel drains back into the tank. most systems have this valve in or on the fuel pump. try this. turn the ign on, but do not start. let the pump run for several seconds, this will insure fuel is in the rail, and available to the injectors. then try to start. if it fires right away, then somehow fuel is not being contained in the rail. dunno if that means new pump, but you gotta find where the valve is.
 

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Discussion Starter #3
Here's a video of it doing a tame version of the stumble-crank. YouTube is littered with other videos of Elantras far less camera shy than mine doing this so I'm not the only one. Fixes ranged from replacing the catalytic converter to a new fuel pump or the inhibitor switch. None of these things are cheap, either.

https://youtu.be/n2MRw0NPIRk
 

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The inhibitor switch is indeed cheap. I bought one off of Amazon. I think it was around $30. But I doubt that is the cause as when mine was failing the symptoms were drastically different.
 

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dunno about your car specifics, but fuel has to stay in the rail to feed the injectors. there is a valve, anti drainback, when the system is shut off, this valve will prevent all the fuel from draining from the rail. when the car sits for a long time, if the valve is bad, fuel drains back into the tank. most systems have this valve in or on the fuel pump. try this. turn the ign on, but do not start. let the pump run for several seconds, this will insure fuel is in the rail, and available to the injectors. then try to start. if it fires right away, then somehow fuel is not being contained in the rail. dunno if that means new pump, but you gotta find where the valve is.
I was thinking the same thing.
Got to put a fuel pressure gauge on the fuel rail and check if it hold pressure.
If it doesn't hold pressure then got to figure out where it is going
ie, stuck open injector, anti drainback, pressure regulator, fuel pump, etc.


Don't know if this is a push button start or uses a key.
If key then turn to on position a few times and then crank to start
If it starts up right away then fuel pressure is the issue

Oh, start button .... hmmm
 

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So let me get this straight. If she sits 3-5 hours it's a rough start but sitting shorter or longer is a smooth start?

I sometimes get that stumbling crank start after a very short start and stop like moving car out of garage and parking on street but this only happens a few times a year.

What are you scanning with to know it trips no codes?
 

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So let me get this straight. If she sits 3-5 hours it's a rough start but sitting shorter or longer is a smooth start?

I sometimes get that stumbling crank start after a very short start and stop like moving car out of garage and parking on street but this only happens a few times a year.

What are you scanning with to know it trips no codes?
if it is the drainback valve, since it is a mechanical device, it wont throw a code. since the valve is mechanical, partial failure/full failure is not consistent. kinda like a ball/spring closing off flow. over time, the ball or the socket gets worn, or the spring gets worn. moving the car out of the garage could also be loading up the plugs, because it is in cold start mode, and it needs to run a bit. in the old days, when a cold start valve was part of the system, this would happen a lot. and i am only suggesting here
 

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Discussion Starter #8
So let me get this straight. If she sits 3-5 hours it's a rough start but sitting shorter or longer is a smooth start?

I sometimes get that stumbling crank start after a very short start and stop like moving car out of garage and parking on street but this only happens a few times a year.

What are you scanning with to know it trips no codes?


Correct. Stone cold and hot starts go off without a hitch every time. I too have gotten the short run starting issue but this is different.

Using an Ancel OBDII scanner. No stored or pending codes.


Sent from my iPhone using Tapatalk
 

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Long crank time before fire --

Put a fuel pressure gauge on it and watch for residual pressure.. thing may dropping to "0" and then not come right back up with first key cycle (slow to build system pressure)

Rare to see pump in the UD/MD,, but we have replaced a few in the past..

If I recall, fuel line pressure runs upward 55-60 PSI

Dont know if you have access to BG Fuel test kit as supplied to Hyundai, check this load of fuel for alcohol content,, around here, typical is 10% per pump sticker and rough vial test (BG)


We had a new one that drove kids crazy,,(not my project).... turns out Hyundai has ground wire from pump grounded to stud on floor where seat rise drops down to foot level of floor under carpet,, it was loose from factory,, and stoooopid place to put it also with wetness / slop from wet shoes to wet the carpet over time,, canidate for grind and plenty of lube to slow down corrosion of ground over time
 

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Andrew, keep us posted on this one. I like @sbr711's post. For a LOT of reasons. But primarily because it's the simplest and easiest to perform.
 

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Discussion Starter #12
Put a fuel pressure gauge on it and watch for residual pressure.. thing may dropping to "0" and then not come right back up with first key cycle (slow to build system pressure)

Rare to see pump in the UD/MD,, but we have replaced a few in the past..

If I recall, fuel line pressure runs upward 55-60 PSI
Hey sbr...where is the hookup for the tester?

This is definitely a heat soak thing because the warmer it is, the worse it gets. I had the car under the car cover in the sun at work and it did it after sitting for 9 hours. It's never done that until I put the cover on it so something in there isn't liking the residual heat that the car cover helped trap. It's almost like vapor lock.
 

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Hey sbr...where is the hookup for the tester?

This is definitely a heat soak thing because the warmer it is, the worse it gets. I had the car under the car cover in the sun at work and it did it after sitting for 9 hours. It's never done that until I put the cover on it so something in there isn't liking the residual heat that the car cover helped trap. It's almost like vapor lock.
Look for alcohol content in fuel (BG has test kit).

The fuel pressure is easiest grabbed at rail where plastic quick connect to rail, need an adapter to fit between fuel line and rail fitting so you can attach gauge there.
 

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Hey sbr...where is the hookup for the tester?

This is definitely a heat soak thing because the warmer it is, the worse it gets. I had the car under the car cover in the sun at work and it did it after sitting for 9 hours. It's never done that until I put the cover on it so something in there isn't liking the residual heat that the car cover helped trap. It's almost like vapor lock.
When you had the battery out, did you check the grounds?

When I replaced the battery I scraped the paint from under the main ground lug, reattached it and coated it with grease. The car jumps to life immediately now. I also sprayed all the other grounds with penetrating oil/rust preventer to keep them from corroding.

Some people add an 8GA wire directly from the battery to the engine.

I would investigate this before throwing more $$$$ at it. All it costs is an hour or so...;)
 

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PS: I couldn't believe what I found. Where the lug was located it was painted with "underhood" paint. It's a duller paint of the same colour used to paint areas that aren't seen. The paint is applied after the hole for the lug it drilled and tapped.

They install the ground lug, and the only thing they rely on is the bolt cutting into the paint in the tapped out hole to provide grounding. Only half the paint was removed from the threads in the tapped out hole.
 

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Discussion Starter #16
The grounds have been taken care of in this car numerous times.


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The grounds have been taken care of in this car numerous times.


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You'll have to look elsewhere than the grounds...:D
 

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Ill roll with fuel system. Grounds are good because you have a good cranking speed, does not sound like its in labor. Looks like it is taking more time to load the rail up, or valve is stuck on the fuel tank purge, causing a minor flooding on a hot start. I would do as described earlier with the fuel rail, then go for the purge valve in the tank area.
 

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Discussion Starter #19
This issue is continuing to get worse and worse and my dealer refuses to / can't do anything about it "because there's no code". It used to stop happening in cold weather and now it does it even with temps in the 40s. It used to not do it after sitting overnight and even now, it sometimes stumbles on the morning's first start. I can't afford to throw a $600 fuel pump at this thing only to have it not fix the problem. Is it ever going to reach a point where it just cranks and doesn't start at all?
 

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This issue continues to deteriorate and with my recent cylinder 2 misfire on a cold start (no cranking issue that time) that did not chase to cylinder 1, I've decided to pull the trigger and throw a crankshaft position sensor in there. It's $100 and I can put it in myself...cheaper than a fuel pump even if it doesn't solve the problem. If it doesn't fix it I'm just going to give up on solving it...this car will be gone in a year anyway.
 
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