BenzKidd

Detailed summary:
PT1
Had noticed small sputters at very low RPM's while in traffic. Very mild, the RPM's would slightly drop and it almost felt like it was choking. You could feel it nudging forward slightly trying to "catch the stall" is what it felt like. Only happened at very low cruising RPM's >500RPM's while I was not giving gas and letting it move itself forward. Few days later I drove a few miles to a friends house >10min drive. I was just picking something up and I turned the engine off while I was waiting for him. Drove back home and at a red light right before my house, my car just shut off. There wasn't any rough idle or any warnings, felt like I turned the key off. All electrical and stereo still running. I tried turning it back on and it would turn over but not start. Pushed the car home and let it sit for a few hours. Came back to it and it started up again. Let it idle for about 10 mins and it died again. Same thing, very smooth like the key had been shut off. The car would not start after again. Would turn over but not start.
PT2
Towed my car to the stealership to have it diagnosed. Originally I thought it was fuel related and told the dealer I would occasionally smell gas inside. They called me back and told me its throwing a Crank Position Sensor code. They did confirm the fuel tank needed to be replaced as well under warranty. I opted out of having them do the CPS (they wanted $625) and just had them do fuel tank. Ok so here is where things get interesting. They called me to let me know the work was done. They also told me that it seems to be dying for multiple reasons now. They told me sometimes it would throw crank position sensor and die smoothly, or it would sputter and die now and they said it threw multiple codes. So, I ended up towing it home and replacing the CPS with a OEM from FCPEuro. Please note, I did not attempt to start the car before doing the CPS.
PT3
Ok, so after doing CPS and having dealership install new fuel tank this is my issue. It will now start up every time. Slightly rough and high idle, like a cold start, and when it comes time for the RPM's to drop down, the car sputters and shuts off. Almost like I am running out of fuel or something. It's not a crazy sputter, just a small one and then it shuts off. After shutting off it will still start right back up again. Before it did not start up again for a while. Also before, it would idle for a while, now it dies within 30 seconds. When the rpms start to drop and sputter, if I give it gas the RPM's will climb, and then like it loses fuel just sputters and shuts off. Even if I am maintaining RPM's they'll eventually just drop off, again like it runs out of fuel. I tried replacing the fuel pump relays (my car has 2) and that did not fix it. Also, the plugs looked perfect and not melted like I've seen in some photos.

What I know:

Ok so in my research I've heard of a few things happening. First off is the CPS which I don't believe was my issue. Also, I've heard of the new pumps and the reversed polarity. I talked to my buddy who actually works at the shop where I had my work done, and he told me he knew about this and that all new fuel tanks come with a pigtail adapter. He believes it is not the issue. I've also heard of the fried relays, but I replaced both of mine and the connectors looked perfect and not burnt whatsoever.

What I will try:

I am going to attempt to confirm that the fuel pumps are working correctly. I will turn the car on and check to see if the pumps are shutting off before the engine, possibly due to faulty install. I will start here and report back. Will try and take videos as well. If anyone can chime in with some suggestions, would be much appreciated.

tlambert

Check the fuel pressure also.

BenzKidd

Will check pressure.

Also quick note. When I got car back from dealer (week later) had a message on dash saying not all electricals will work. Low battery. Something like that. Today I have a red battery light. I’m going to try and charge my battery. Battery is dated Dec '19. My car does have a sound system with sub and amps.

Question. My crown victoria would die when the alternator went bad is it possible that this is what’s wrong? Tried starting the car with the red battery, It started up and died immediately. I am charging my battery right now and will post results. If alternator was going bad, wouldn't I have gotten a red battery warning before the car started dying?

Another note. A month ago I ordered a custom air intake system and my car sat for about a week. Same thing with the red battery but it started up and was able to charge the battery. Also, there has been a few occasions where I left my lights on, draining the battery enough to get the low battery warning, Every time it was able to start and recharge the battery.

Thoughts?

BenzKidd

Ok. I checked fuel pressure. With the ignition on it's in the low 70's. When I turn the car on it jumps to about 78 but the pressure is not steady. Then pressure drops, car dies. I am taking my car back to MB of Santa Rosa as I strongly believe this is a new issue and they f***ed up my fuel tank install. Will update this thread with results

BenzKidd

Ok last post. Problem is solved and I'll never be taking my car back to MB of Santa Rosa again. The problem ended up what I suspected about the revered polarization in the new pumps. It was completely their fault and they still charged me labor claiming it wasn't working properly before.They claimed that the pumps had been switched in the past and that the polarity were revered then. This is completely false and I believe this is the first time the pumps have been changed. They even stated that the old harness was plugged into. Very upset I pad 487.50 for 2.5 hours of labor to fix their own mistake. Anyone know how I may prove this was completely their fault and that the car dying was due to the original CPS diagnosis and then they broke it when installing the new pumps? Absolutely furious and that's why they call it the stealership boys.

bbirdwell

Even with reversed polarity on one pump pressure would be close to 5.1 Bar at idle; at full throttle and high rpm pressure will drop into 3.x Bar threatening the engine. Your car is running, just verify fuel pressure across throttle and rpm range. Write off the money as a "lesson learned". This is why I do all work myself. If I screw up I know who to blame (picture Jim Carrey in ' Liar, liar' beating himself up in the bathroom).