TL;DR - Car stalled on the highway, gave codes P0171 and P2096, and refused to start after that. Towed it home, and tow truck driver suggested it could be the fuel pump. He said to hit the gas tank. After a bumpy ride home, the car starts and idles fine. Fuel pump problem?


I've read several posts about P0171 and P2096, but they don't have the symptom of the car dying and refusing to start...

Yesterday evening I was driving on the highway at 75 MPH when all of a sudden I lost all power. I coasted to the shoulder and the engine died. I tried to turn it on, but it wouldn't cooperate. It would try to start, but then it would immediately die.

It gave me codes P0171 (system too lean) and P2096 (post cat fuel trim too lean). I'm assuming 2096 is a side effect of 0171.

Since I couldn't get it started, I had it towed to my house. I was talking with the tow truck driver, and after I explained my symptoms to him, he suggested it might be the fuel pump, especially given the mileage on the car (163.5k miles). I've got no idea if the fuel pump has been replaced before, though the last owner did give me the SST to remove the fuel pump.

The tow truck driver suggested hitting the gas tank with a 4x4 to jar the fuel pump, and if that works, I would know it's the fuel pump. He said he's had success getting a fuel pump to work for a short time after doing that.

Today I went to try and start it up, and it started up just fine. I let it warm up to normal temp, let it run for a few more minutes, then shut it off. I waited 30 seconds, then started it back up. It cranked right up. Idle is smooth, and the CEL is gone. Part of the drive home in the tow truck WAS a bit bumpy. Is the tow truck driver right? Could a good bump have given my fuel pump a little bit of extra life?

If not the fuel pump, any ideas what I should be looking at? I just installed my rebuilt engine 300 miles ago. Given the codes and the fact that it cranks up quickly when warm, I'm hopeful it's nothing in the engine itself.

 

How much fuel did you have in the tank? do you make a habit of going below 1/4 tank before refilling?

The fuel pump could simply be dying. I've read others saying that the pump will chug along, working just well enough until it overheats and the car dies. After it cools off, it's fine again.

 

It had just over half a tank. I've never let it go below 1/4 tank. But I've only had the car for a little over a month, and I don't know about the previous 2 owners.

 

Often fuel pumps will quit when they get hot...and they will work for a while again when they are cold

Also remember that the fuel pump enclosure contains the fuel filter...so with 163K you will want to replace the entire assembly not just the pump

 

Thanks to both of you! I'm feeling relieved that so far it doesn't seem like the rebuild is at fault. I'll replace the fuel pump assembly.

 

Well I would not diagnose by parts replacement. I surely could be the pump and/or assembly though as both of those codes a related to a lean condition. But those codes can be triggered by lot's of things.

 

Is the best way to test the pump just to check fuel pressure? Maybe I should start it up, test the pressure, then drive it around for 30 min and test again?

 

Just a quick update on this: I deduced that it was pretty likely to be the fuel pump because of the way it would stall out after driving for a while, and then if I waited 20 min or so it would start back up. Plus, when I turned the key to the on position, the fuel pump priming was way louder than it should be. I replaced the fuel pump a couple days ago, and my car is back to normal now.