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2009 Jeep Commander
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Discussion Starter · #1 ·
Hey folks just a general question. I had a misfire code 303. I bought a single coil pack and wanted to do a fairly quick job to get rid of the code. I had ordered the rest of the coil packs and planned on doing it on the weekend. Replaced the single coil pack. The vehicle started no problem. I let it run for a few minutes in the driveway. I backed the truck out of the driveway and drove down the street. I turned the corner and was literally about
400 m from my house and the truck stalled? I tried to start it and it cranked but it sounded like it wasn't getting fuel. I checked the Schrader valve on the fuel rail and nothing came out? I do feel like my fuel pump was starting to fail but is this just a coincidence? Is there something related that I might be missing? Thanks guys
 

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2008 XK Sport 4.7L V-8 QT-II 4WD 104,xxx Miles
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Hey folks just a general question. I had a misfire code 303. I bought a single coil pack and wanted to do a fairly quick job to get rid of the code. I had ordered the rest of the coil packs and planned on doing it on the weekend. Replaced the single coil pack. The vehicle started no problem. I let it run for a few minutes in the driveway. I backed the truck out of the driveway and drove down the street. I turned the corner and was literally about
400 m from my house and the truck stalled? I tried to start it and it cranked but it sounded like it wasn't getting fuel. I checked the Schrader valve on the fuel rail and nothing came out? I do feel like my fuel pump was starting to fail but is this just a coincidence? Is there something related that I might be missing? Thanks guys
P0303 - Cylinder 3 Misfire

OBD-II Trouble Code: P0303 Cylinder 3 Three Misfire Detected (obd-codes.com)
 

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2009 Jeep Commander
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44 Posts
Discussion Starter · #3 ·
Yeah I've got a good OBD2
I have a good OBD2 reader. I got the code. Misfire on three and I changed cylinder 3 coil pack and plug. Everything worked fine and the code disappeared but then my truck stalled right after the fact? I pushed the Schrader valve on the fuel line because it sounded like it wasn't getting fuel. There was no pressure in the fuel line at all? I just was wondering if it's a coincidence or they could be connected?
 

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2008 XK Sport 4.7L V-8 QT-II 4WD 104,xxx Miles
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8,869 Posts
Yeah I've got a good OBD2

I have a good OBD2 reader. I got the code. Misfire on three and I changed cylinder 3 coil pack and plug. Everything worked fine and the code disappeared but then my truck stalled right after the fact? I pushed the Schrader valve on the fuel line because it sounded like it wasn't getting fuel. There was no pressure in the fuel line at all? I just was wondering if it's a coincidence or they could be connected?
@Fred Zeplon ;

Discalimer: I'm not a mechanic, but, here is my observation;

A code P0303 may mean that one or more of the following has happened:

Faulty spark plug or wire
Faulty coil (pack) Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer

If you look at the possible causes, one of them is "running out of fuel" which is essentially what would be happening, if your fuel pump died and is no longer pumping fuel to your fuel rails. Then you couple that with your own observation, that there was no pressure in the fuel line at all.

So, I'll go out on a limb here & say yes, those 2 issues could very well be connected.

It could very well be the result of a bad fuel pump.
 

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2009 Jeep Commander
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Discussion Starter · #5 ·
@Fred Zeplon ;

Discalimer: I'm not a mechanic, but, here is my observation;

A code P0303 may mean that one or more of the following has happened:

Faulty spark plug or wire
Faulty coil (pack) Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer

If you look at the possible causes, one of them is "running out of fuel" which is essentially what would be happening, if your fuel pump died and is no longer pumping fuel to your fuel rails. Then you couple that with your own observation, that there was no pressure in the fuel line at all.

So, I'll go out on a limb here & say yes, those 2 issues could very well be connected.

It could very well be the result of a bad fuel pump.
That is what I am guessing. I think I have been dealing with this for over a year. I had some issues in the past with fuel boiling in that fuel rail. Apparently that 3.7 l never had a proper purge valve. So instead of the fuel going back down in the tank it stayed in that line and cooked? Another Chrysler faux pas haha. Thank you sir I appreciate your input.
 
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2008 XK Sport 4.7L V-8 QT-II 4WD 104,xxx Miles
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That is what I am guessing. I think I have been dealing with this for over a year. I had some issues in the past with fuel boiling in that fuel rail. Apparently that 3.7 l never had a proper purge valve. So instead of the fuel going back down in the tank it stayed in that line and cooked? Another Chrysler faux pas haha. Thank you sir I appreciate your input.
No problem FZ, let me know your results when/if you replace the fuel pump, if you don't mind.
 

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Discussion Starter · #7 ·
No problem FZ, let me know your results when/if you replace the fuel pump, if you don't mind.
Absolutely. I don't have time to do it until Sunday or Monday but I crawled underneath and oddly, it looks fairly new and clean all around the tank. My buddy replaced his on his 07 Hemi and it was complete rust show. He had a custom make new braces.
 
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