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#4070024 - 07/07/20 07:09 PM Does the 4.6 easily flood itself when cranking?
Appleboy76 Offline
Stranger

Registered: 11/16/19
Posts: 8
Loc: US
Before I start, keep in mind that I am not mechanic, so feel free to correct me where you feel necessary.

In the year and 1000 miles I’ve had my 09 MGM, it has always started the way it should when it was expected to start except for three separate instances. All three of those times, I suspect it had something to do with engine flooding.

This only happens on a cold start in a situation where the driver would accidentally let go of the key before the engine fires. The first time this happened, the engine took a couple of cranks to actually get it to start. It started the first time on the second and third instances, but it would stumble for a second before it climbed up to normal RPMs.

Another thing I noticed is that on my commute to work where I mostly drive 55-60 MPH for about 10 miles, I would only get 20 MPG (Dropped to 19.3 after replacing the dry-rotted Firestone Precision Touring tires with Toyo Celsius tires) compared to the EPA-rated 24 highway. Though, I have no idea if the previous owner did spark plugs, so the spark plugs very well could be the original with 120,000 miles on them.

Here are my questions:
1. Do these engines easily flood themselves when cranking them, especially on the second cranking attempt?
2. If the answer to the previous question is no, could it possible that these are symptoms of a leaking fuel injector? When the car is running, it always runs the way it ought to with no CEL. I also only see smoke coming out of the exhaust at temperatures under 60F. As I said before, spark plugs might also be a factor. Any other suggestions?

Some additional information if you feel like reading on. For the videos, I left about 10-20 seconds idling after the cold start, so you only really have to watch the first 5-10 seconds of each.

Regular cold start for reference:
https://youtu.be/0SghgcEtq-Y
The engine was a little noisy here. This was back in April, and the car did sit for a few weeks prior to the cold start. It hasn’t been this noisy since.

Instance 1 (Late March 2020):
The first time happened, my dad took my MGM to work. After 8 hours, he went to go home. The car did not start for him on the first try, and he said it took a couple of cranks for it to start. He did say he thinks he might have let the key go to early the first time. He normally drives a 2013 Chevrolet Silverado. Those who’ve experienced mid-2000s and new GM products probably know you only need to flick the key to start the engine, and that you don’t need to hold the key in the start position until the engine starts.

Instance 2 (Monday, July 6, 2020):
https://youtu.be/9aNAqR5EJ-Q
The night before prior to the video at around 10 PM, I was trying to read the label on my serpentine belt to find out how old it is (The belt is squeaking, and I figure it might be time to replace both the belt and the tensioner). I got in the car and bumped the starter a few times so I can spin the engine over a little bit without having to start the engine. The next morning at around 7AM, I went to start the engine, and it took a second for the RPM to climb up to normal cold idle.

Instance 3 (Tuesday, July 7, 2020):
https://youtu.be/QreKppQpTqQ
After thinking about what happened the day before as well as all the other information I provided above, I thought I would see what would happen if I intentionally tried to flood the engine. In the video, I got in the car and turned the key to start, but then I intentionally let go of the key too early. The second time, I tried to start the engine, and it did stumble a little bit. Though, it did start a lot more normally compared to the last two instances.
_________________________
My car: 2009 Mercury Grand Marquis LS Ultimate Edition. 4.6L V8 2V FFV.
Family vehicles: 2013 Chevrolet Silverado 1500 LT 5.3L 2WD Extended Cab 6 ft Bed
2002 Nissan Maxima SE

All vehicles are stock

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#4070074 - 07/08/20 07:25 AM Re: Does the 4.6 easily flood itself when cranking? [Re: Appleboy76]
Old_Guy_Stu Offline

Over the Hill

Registered: 04/28/19
Posts: 1264
Loc: Cleveland, OH
It's pretty hard to flood an engine with EFI. Generally, a flooded engine will require you to floor the pedal when cranking to try to normalize the A/F ratio (Ford ECU's actually have a "flood mode" that kills the injectors when you do this), and then belch out a huge black cloud when it catches.

I'd be looking at plugs first.


Edited by Old_Guy_Stu (07/08/20 07:27 AM)
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#4070082 - 07/08/20 10:31 AM Re: Does the 4.6 easily flood itself when cranking? [Re: Appleboy76]
BigMerc96 Offline

I know nothing
Posting Addict

Registered: 06/05/10
Posts: 19761
Loc: I can see Detroit from here!
All of mine have done this if you crank them over but stop before the engine starts, if you then try and crank them they'll crank about twice as long before actually starting. My Dad's E150 would do this too. I suspect they are possibly flooding a bit, the startup routine for a Ford EEC-IV and EEC-V PCM (for a SEFI engine) is to batch fire the injectors (and coils in the case of coil on plug) when cranking until a stable cam and crank sensor signal is achieved, this means its firing injectors in pairs and one of those cylinders won't actually be on the intake stroke but the other will. It will in theory be able to get one of those cylinders to fire and once that happens it'll spinning fast enough to establish the cam and crank signals needed to properly time and sequentially fire the injectors/coils. Another strong possibility is that the fuel line pressure is used up on the initial crank and if you try and crank again immediately it doesn't prime the pump again so there isn't enough pressure to reliably fire. Its just an oddity that they seem to do. I doubt it actually hurts anything.
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#4070084 - 07/08/20 11:06 AM Re: Does the 4.6 easily flood itself when cranking? [Re: Appleboy76]
ClayBelt Offline

Over the Hill

Registered: 04/03/18
Posts: 1391
Loc: Leon County
It takes a second when you quit cranking prior to it fiiring . It’s even worse if you have an exhaust leak by the O2 sensor, but it’s normal behavior
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#4070108 - 07/08/20 07:52 PM Re: Does the 4.6 easily flood itself when cranking? [Re: Appleboy76]
Appleboy76 Offline
Stranger

Registered: 11/16/19
Posts: 8
Loc: US
Sorry for the long response. I did get a little lazy on replying.

Based on what I’m seeing, this is normal behavior. Based on how the system works, I could maybe see how the engine could somewhat flood when cranking (assuming you can have a partial flood). I have heard of clear flood mode, and I would consider it where I feel appropriate. The fuel rail being dried after the first crank sounds logical. I usually switch the ignition switch to the ON position, waiting a second, and then I would start the engine which could by why it always starts the first time for me.

About the fuel economy, I do need to look at the spark plugs. As I said before, they very well could be 11 years old with 120,000 miles.

Thanks for the responses.
_________________________
My car: 2009 Mercury Grand Marquis LS Ultimate Edition. 4.6L V8 2V FFV.
Family vehicles: 2013 Chevrolet Silverado 1500 LT 5.3L 2WD Extended Cab 6 ft Bed
2002 Nissan Maxima SE

All vehicles are stock

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#4070112 - 07/08/20 09:08 PM Re: Does the 4.6 easily flood itself when cranking? [Re: Appleboy76]
2007CrownVic Offline
Over the Hill

Registered: 11/19/11
Posts: 2974
Loc: Canada
You're not going to flood the engine with those quick no starts. You could have starting problems where you're holding the key for long periods several times in a row and still not flood it.
All your videos are normal starting don't obsess over it, you'll be able to tell if there's a real problem.

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