Jeep Commander Forum banner

Coil Pack/failed fuel pump?

469 Views 7 Replies 2 Participants Last post by  Fred Zeplon
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
1 - 5 of 8 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.
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.
  • Like
Reactions: 1
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.
  • Like
Reactions: 1
No problem FZ, let me know your results when/if you replace the fuel pump, if you don't mind.
Ok... here's the Bought the fuel too difficult to drop the tank. A couple of recommendations are...try and get the fuel out beforehand as I had 3/4 of a tank! Dropping it was not to bad but trying to reinstall it was nuts. I went and bought a pump and drained it. Much easier. Also take the driveshaft off at the rear...and remove the spare tire!!! The filler hose on the tank end was essentially melted to it. Giving myself more room with spare gone allowed me to get a better attack
Anyhow.... I replaced the fuel pump and reinstalled the tank. I started up the truck and it was doing the exact same thing it was doing beforehand haha.... Throughout the week I had been watching a ton of videos regarding installation of the tank. One of the videos that I saw was a guy having exact same issue that I was. He changed his map sensor. Just for fun after being severely angry haha I took out the sensor and it was completely black on one side. I used some cleaner and cleaned it off and now my truck runs perfectly haha I am getting better fuel economy though so the pump was likely not functioning properly anyway.
Long story short is that I replaced a fuel pump for no reason!!!
See less See more
1 - 5 of 8 Posts