Fuel pressure drop when sitting

[JerEazy]

I did some searching first but I want to confirm once more before diving in.

1990 e30 325i - there is no pressure in the fuel line after sitting over night. But there is still fuel in the fuel rail. This leads me to think a check valve issue. But in the later models the check valve should be in the fuel pump, and the fuel pump is new OEM. Is there somewhere a check valve should be? Or should I install and inline one?

FPR and injectors are new as well.

[roguetoaster]

You can add one at the outlet of the pump if you want. I did that on several cars that had newer pumps, but bad check valves for whatever reason.

If you search for HB check valve you should find it, and 5/16" is the most common size that will fit. Just understand the pressure ratings and material compositions listed of the unit you go to buy before you slap it into a fuel system.

[TobyB]

There are lots of places fuel can go- the regulator's easiest to check,
but my 'leak-o-meter' would be rather suspicious of 'new' injectors in this
globally outsourced age.

t
old is not better, but new can be crap.

[JerEazy]

Appreciate that. The additional reason I doubt injectors is it was a problem before them and is still a problem now. So there is absolutely a possibility. But when I remove the fuel I let to the injector rail (or FPR) there is no pressure. But the rail is still full of fuel. Will add a check valve and see

[JerEazy]

dupe post. Sorry