[Walker16]

Watching ista I can see the rail pressure sensor hit 14mpa while cranking but as soon as it stops it steadily drops to about .15mpa after about 10 seconds. When I try and start the car it will fire up for a second or 2 then die. Could this be a leaking injector causing this? HPFP was just replaced last week thinking that was my problem. All other low pressure function tests on ista seem fine.

[sabino56]

I don’t know about your model but I had problem with starting on my 2006 E90 due to fuel pressure dropping after key off. It was caused by a failed fuel pressure regulator under the rear seat.

[Walker16]

i was thinking about that too. just not sure how to figure out if the pressure loss is before or after the hpfp...

[Walker16]

also durring the last ista scan i had a code for rail pressure too high (002BF2) never had that before. code only showed during crank attempt cause i showed non existent after a ista refresh..

[sabino56]

I don’t know about the hpfp or fuel system on those cars but would guess the Fpr function is similar to earlier/E90 in that there is a check valve in Fpr to maintain whatever pressure is in the rail after key off? That is, if the fuel pressure is ok when running and drops quickly when off the check valve is bad - not the fuel pump.
You can probably google/find YouTube videos on it and/or perhaps someone who actually has experience on that will comment.
It’s not too hard to get in there and replace - look in the DIY section for potential help.
Good luck!

[Walker16]

Car won’t start to monitor running pressure. During crank it hits 14mpa then after cranking it drops to almost zero in about 7 seconds. HPFP is brand new from ecs and plugs are new. Zero codes on ista as well. Really stumped on this one. Pulled all injectors and put them on the rail while unplugged to see if they were leaking but they were all good. Not a drop out of any injectors. Where else could the fuel bleed off to??

[NZE90]

I would say you need a new fuel pressure regulator. It's in the LH side of the fuel tank.

[Walker16]

Originally Posted by NZE90

I would say you need a new fuel pressure regulator. It's in the LH side of the fuel tank.

cool ill look into it. no leaks i can see so the pressure from the rail has to be going somewhere. back in the tank makes sense..