How do I tet fuel pressure on 540i m62 V8?

redbull713 · Oct 1, 2011

I know on the inline 6 there is a shrader valve but not on the v8. So how do I test? I heard that I can rent an adapter or something from autozone, does anyone have any info?

JimLev · Oct 1, 2011

The newer V8's do have a schrader valve. You need a gauge that you can Tee into the fuel line.
Are you having problems? If so and you have never changed your fuel filter I'd change it.
Your fuel pressure at idle should be about 52 PSI.
Leave the gauge connected and turn the engine off. The pressure shouldn't drop more than 7 PSI in ~20min.

bluebee · Oct 1, 2011

JimLev said:
The newer V8's do have a schrader valve.

What about the 2002 525i?

Do "I" have the schrader valve on my M54 engine fuel system?

JimLev said:
Your fuel pressure at idle should be about 52 PSI.

Is that for the V8 or for the I6?

How would a 'clogged' fuel filter affect the fuel pressure?

JimLev said:
Leave the gauge connected and turn the engine off. The pressure shouldn't drop more than 7 PSI in ~20min.

What does it mean if the pressure 'did' drop more than 7 psi?

Would that mean:
a) A leak?
b) A clogged fuel filter?
c) A worn out fuel pump?

edjack said:
I've not investigated the AutoZone device, but it needs to have the proper quick couplers to connect into the fuel line. Go ask them.

I called the Autozone in San Jose California on 2690 Story Road (408-254-4865) to ask.

They have an all-inclusive fuel pressure testing kit, P/N CP99208, which they'll lend to you for a deposit of $150 (which you get back when you return the kit within 90 days).

edjack said:
Harbor freight has a deluxe kit that seems to have the requisite fittings. As I recall, the kit is $130.

Since the Autozone kit is free (in effect), that's the way to go for one-shot fuel pressure testing for me.

However, this quest is moot if the M54 doesn't have the schrader valve.

Unfortunately, I can't find the CP 99208 by googling (wrong number?).

Can someone confirm that the 2002 M54 is 'testable' by a 'standard' Autozone $150 deposit fuel pressure test kit free loaner?

edjack · Oct 1, 2011

Jim, he doesn't have a "newer" car.

I've not investigated the AutoZone device, but it needs to have the proper quick couplers to connect into the fuel line. Go ask them.

Harbor freight has a deluxe kit that seems to have the requisite fittings. As I recall, the kit is $130.

JimLev · Oct 1, 2011

ed, right. I was just mentioning it for the ones that have a 9-98 or newer cars. At least I think that's when they started putting them on the fuel rail.

Joeboss · Jul 25, 2021

Find the 98 doesn't have one thanks for the disinformation

bluebee · Oct 11, 2011

To locate the M54 engine fuel system Schrader valve, I opened a separate thread ...
- Where is the M54 fuel line schrader valve (to test lean condition fuel pressure)?

edjack · Oct 11, 2011

This one looks like it would fit: http://www.harborfreight.com/master-fuel-injection-pressure-test-kit-97706.html

How do I tet fuel pressure on 540i m62 V8?

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