I have a 2001 QX4 with the 3.5 (duh)

I have been trouble shooting an occasional rough start condition..

I did a fuel pressure test directly off of the fuel pump see pictures...

It did it this way due to the fact that i do not have the adapter that fsm calls for.

It was giving me a reading of 25psi while idling Is this too low?


The fsm calls for between 34-43psi i believe but that is testing it after the fuel pressure regulator i believe....

Just wasn't sure how I should be reading these results...wanted to double check before replacing with an oem Bosch

I would say that it is a bit low if you're checking right at the pump. I would go ahead and toss a new one in there.

Agreed, that is low. Testing at the fuel rail might yield different results, but I'd imagine they'd be lower if anything.

Let me know if replacing it doesn't help the hard starting issues. I spent a few weeks and a pile of money tracking the same issue down on mine.

Word of warning regarding fuel pump brands: I bought the Delphi FE0388, which turned out to be a rebranded Bosch and was about $70 cheaper! The documentation that came with it was Bosch-branded and everything Apparently the two companies sell each others products so they don't have to manufacture pumps for every vehicle out there.

While you're changing your pump, consider replacing all rubber hosing and clamps while you're at it. You only need 10 or so feet, and it's great peace of mind. There's a piece running from the tank to the filter, from the filter to the metal line, from the fuel pressure regulator to the metal line, and from the metal line to the tank. You'll need EFI fuel line, which is made to handle the higher pressures. I went with Gates 27340 fuel line and Gates PowerGrip clamps. The clamps are really awesome: you hit them with heat and they contract, crimping down on the line.

Oh yeah, and definitely change the filter if you haven't already!

Good luck and post back with the results!

Nice job! -looks like you were on the right track on the fuel pump.

Good to know about the delphi pump. I have a delphi fuel pump in my truck and it has been great. I just have had terrible and heard bad things about the airtrex pumps. When i do a job i prefer to just do it once. And thank you for the info on the hoses As well. The filter is new already so good there.

I will post pictures of its new backend soon as i hope to finish the job today.

4xq, thanks for all the help you have given me. My p0455 code has not popped back up in almost two weeks. I still can't track down the source of the gas smell from around the gas cap area. I pulled that tire and cover off. The fuel filler pipe was fine actually in pretty good shape with no rust and the smell did not appear to be emitting from any where on the pipe. Nor does it appear to be emitting from the gas cap itself which makes sense as it is a brand new oem cap... I wasn't brave enough to try your match suggestion... Lol