**edit, problem went away. Seems to have fixed itself.**

I have no idea why my car started doing this. I have been searching around for a while now and have found the answers about 50/50 that it's okay, and it's not okay.

I have a stock fuel pump, fpr, injectors etc. I have a mechanical B&M fuel pressure gauge located on the fuel filter.

Okay, so I installed the B&M gauge a few months ago and it has always maintained pressure for a while after I shut the car off. If I prime the fuel pump it would stay around 40 psi for a number of minutes. It would take over night for the fuel pressure to drop all the way to zero. From what I understand this is normal operation.

Today I drained out my AC and removed my hardlines, compressor etc. but I did nothing to the fuel system what so ever. I didn't touch it at all. I got home after draining the AC system and when I popped my hood to start doing some work, I noticed that the fuel pressure dropped to zero within 10-15 seconds after turning the car off.

So I primmed the fuel system a few times and noticed that each time it would drop back down to zero within a few seconds.

I wouldn't think this was abnormal, but it was holding pressure before, and not now. I checked my fuel filter, gauge, injectors, fpr etc. and could find absolutely no leaks. No smell, no nothing. There appers to be no leaks.

A few questions...

1. Is this okay? Is this normal? It's just weird that it would hold pressure before and not now.
2. Could it have to do with the colder weather? I read in another thread that the weather can affect it.
3. What possible parts could be failing if any? Could this be a sign that my fuel pump is going to ---- on me? Does my fpr need to be replaced?

Thanks for the help!! I searched and searched and couldn't find any good answers on this one. I did learn that there is some sort of check valve in the fuel pump that is supposed to hold pressure in the lines so the car starts up right away. What would cause this valve to all of a sudden not hold pressure any more?

 

There is a check ball in your fuel pump thats suppose to hold pressure, It could be stuck.

Your fuel pressure regulator could not be shutting all the way when it sees atomospheric pressure.

One of your fuel injectors could be stuck open slightly.

 

i'd put money on the fuel pump check valve. I doubt there's any way that an injector or the FPR could drop 45 psi of fuel pressure instantly.

 

So, it's no problem then? I dont' think my injectors or fpr are dumping the fuel pressure, my bet would be on the fuel pump.

If it's just dumping that fuel back into the tank then it's really no big deal right? Is there anything I can do to get that valve unstuck? Like use some fuel system cleaner or something?

 

You could try a cleaner, but don't expect anything amazing.

You usually see pressure drop with a weaping injector or some other minor leak, but not like you are explaining. The injector or other small leak would not just drain the system instantly. Rule out any leaking connections on the rail and lines and call it good.

 

Thanks for all the suggestions.

I suppose it has fixed itself!

I went out on my lunch break today and drove for a while, then pulled over and popped the hood to see how fast the fuel pressure would drop as well as listen to the injectors to see if I could hear if any of them were leaking. Well, I waited for almost 30 minutes and the fuel pressure never dropped at all. In fact, it looked like it went up a bit. lol

Right when I turned the car off the pressure was at 37 or so and it slowly crept up and held at about 40.

Anyways, it's not dropping any more so I suppose whatever was leaking, stopped leaking... or something.

Thanks for the help though.

 

See! The people on this board are so all you've got to do is park it outside during lunch and they will get right in your car and start to work on ... things.