engine died on me

[Rhett]

Hello, maybe some you guys can point me in the right direction here. My normally reliable truck has started buckin up on me in the last few days.

A few days ago I was on a trip and the CEL came on, and truck ran rough. After I got home I ran the codes and it showed 177, which is O2 sensor rich. Ok, O2 going out, I can handle that.

But now, today I was driving and my truck's engine died. It happened twice in about 20 minutes of driving, and in both cases I was moving at typical traffic speed (30-40 mph). Luckily I was able to restart the vehicle after trying a little. I checked for loose plug wires, loose battery cable, alternator, etc. but all is good. I thought maybe clogged fuel filter. hmm. It showed CEL, so again tonight I ran the codes, since I suspected a new code because it never died before. This time it showed 177 from before but also 543, which indicates open circuit between the battery and PCM. Is this a fuel pump relay going bad?

The O2s I will change, they're due anyway. But I'm not sure if I'm barking up the wrong tree on the fuel pump relay. I know how a bad FPR can foul O2s. Maybe it's the FPR? Maybe once I change the O2s I'll be ok? Can a bad O2 cause the engine to die? Can a bad O2 screw up the fuel pump relay?

 

[aldive]

Did you check the fuel pressure?

 

[mrboyle]

It sounds like your fuel pressure regulator is bad. My X set the same codes when mine failed.

 

[SteveVB]

Fuel System

I think your on the right track with the fuel system, the failing O2s and the codes are the results of something, and my guess would be the fuel pressure regulator/ or the fuel system.
Bad O2s wont cause a problem with the pump relays or the regulator, but a bad regulator and a bum relay can destroy the O2s.

 

[Rhett]

No, I haven't yet checked the fuel pressure. I'll definitely have to do that when I break into it though. I'll probably end up changing the O2s, FPR, and fuel filter for starters. After I do that I'll post in this thread. Thanks for the info!!

 

[asp84]

Definately change the oxygen sensors....... My oxygen sensor become disconnected one time on my 1994 4.0L, when it did, it randomly caused the engine to buck and loose power and sometimes die.

 

[Rhett]

A friend of mine told me about his Dodge pickup that had a bad O2, and its engine would randomly die too, until he put a new O2 in.

Well, now both O2s are changed and so far so good. The truck seems to have more pep to it now. Maybe that's just my imagination though.

I checked fuel pressure and it was 35 psi at idle, which is about where it's supposed to be I think. I also disconnected the vac tube and tested it. I just couldn't find any problems with the fuel pressure regulator. I hope I'm right on that, otherwise I have a feeling I'll be changing O2s again in a month or two. If that happens I'll just change the FPR immediately. But for now it seems ok. The fuel pump relay was ok too.