How does the BMW E39 sucking jet pump (aka suction jet pump) work & how does it fail?
EDIT: It's a vacuum multiplier, which provides more than manifold vacuum could alone, to the brake booster where behind the master cylinder. The air flow goes from the brake booster to a hose at the top of the SJP, to your intake manifold hose on the bottom of the SJP & at the same time to the upper snorkel tubing at the F connector from the middle of the SJP where the venturi effect multiplies manifold vacuum to the brake booster.
This sucking-jet-pump specific thread was prompted by new information today:
- E39 (1997 - 2003) > Different scanner. New code
By the title, you'd never know there is good information therein about the "SJP", and, a thread with that title on another forum is rather sparse; so, I figured we'd give it its own detailed thread on Bimmerfest. As always, this is to edify the tribe as a whole, and to server as a reference in the future, long after we're gone.
Here is the diagram for the 2002 M54 sucking jet pump:
- Engine => Vacuum control => Vacuum control - engine
Note: In the 2002 M54, it seems the following is the case:
1. The top hose appears to go to the brake booster
2. The bottom hose appears to go to the intake manifold on the M54 (or to the CCV on the M62TU)
3. The center venturi tube (despite the diagrams) goes to the F connector on the intake snorkel boot
Please note that the diagram is wrong in quite a few ways. One error is the "L" elbow is actually an "F" connector in the M54. (Apparently BMW didn't update the diagram between the M52 and M54 when they moved the fuel pressure regulator and CCV valve hose connection to the F connector on the intake snorkel).
Another error is the number of hoses & tubes on the sucking jet pump (only one hose and one tube are shown but there are actually two hoses and one tube attached to my M54 suction jet pump).
Here is a picture of my 2002 M54 sucking jet pump in situ (but with the tube to the F connector removed):
Here's that same picture only zoomed out so you can get an engine-bay perspective:
Note: In this picture above, the F connector vacuum tube has been removed; the two hoses (one at the top, and another at the bottom of the sucking jet pump) are in place.
The question for this thread, is:
Q: How does the BMW E39 sucking jet pump (aka suction jet pump) work & how does it fail?
See also this rather ambiguous thread (from another forum):
- What is the purpose of the "Sucking Jet Pump"?
And, view this nice PDF from RDL which explains the sucking jet pump operation on page 12:
- 03 E85 M54 Engine.pdf
EDIT: It's a vacuum multiplier, which provides more than manifold vacuum could alone, to the brake booster where behind the master cylinder. The air flow goes from the brake booster to a hose at the top of the SJP, to your intake manifold hose on the bottom of the SJP & at the same time to the upper snorkel tubing at the F connector from the middle of the SJP where the venturi effect multiplies manifold vacuum to the brake booster.
-----
This sucking-jet-pump specific thread was prompted by new information today:
- E39 (1997 - 2003) > Different scanner. New code
By the title, you'd never know there is good information therein about the "SJP", and, a thread with that title on another forum is rather sparse; so, I figured we'd give it its own detailed thread on Bimmerfest. As always, this is to edify the tribe as a whole, and to server as a reference in the future, long after we're gone.
Here is the diagram for the 2002 M54 sucking jet pump:
- Engine => Vacuum control => Vacuum control - engine
Note: In the 2002 M54, it seems the following is the case:
1. The top hose appears to go to the brake booster
2. The bottom hose appears to go to the intake manifold on the M54 (or to the CCV on the M62TU)
3. The center venturi tube (despite the diagrams) goes to the F connector on the intake snorkel boot
Please note that the diagram is wrong in quite a few ways. One error is the "L" elbow is actually an "F" connector in the M54. (Apparently BMW didn't update the diagram between the M52 and M54 when they moved the fuel pressure regulator and CCV valve hose connection to the F connector on the intake snorkel).
Another error is the number of hoses & tubes on the sucking jet pump (only one hose and one tube are shown but there are actually two hoses and one tube attached to my M54 suction jet pump).
Here is a picture of my 2002 M54 sucking jet pump in situ (but with the tube to the F connector removed):
Here's that same picture only zoomed out so you can get an engine-bay perspective:
Note: In this picture above, the F connector vacuum tube has been removed; the two hoses (one at the top, and another at the bottom of the sucking jet pump) are in place.
The question for this thread, is:
Q: How does the BMW E39 sucking jet pump (aka suction jet pump) work & how does it fail?
See also this rather ambiguous thread (from another forum):
- What is the purpose of the "Sucking Jet Pump"?
And, view this nice PDF from RDL which explains the sucking jet pump operation on page 12:
- 03 E85 M54 Engine.pdf