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How does the BMW E39 sucking jet pump (aka suction jet pump) work & how does it fail?

169K views 82 replies 25 participants last post by  RJay.86 
#1 · (Edited)
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.

I believe this is how the SJP works:
a) The F connector is not a vacuum (negative pressure) source. It a supply (positive pressure) source, providing access to filtered air flow.
b) The SJP is a vacuum multiplier of the intake manifold negative pressure. See below.

a) The check valves are needed to prevent airflow from reversing direction back into the brake booster. Two valves are needed to cover both entry points back into the booster. Since the pressure in booster is now lower than the intake manifold (due to the SJP effect) side and the F connector side, air can flow into the booster if there were no check valves.
b) The venturi constricts airflow in one channel, causing the airflow to accelerate (think of a wing with the straight channel below the wing and the venturi above the wing surface). Just like a wing, you get a reduced pressure above the wing (venturi side). The negative pressure at the venturi (where the two yellow lines join) is greater than the negative pressure at the intake manifold, thus air flows from the booster into the SJP, creating more vacuum. This is the net effect of the multiplication factor of the SJP.
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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

Suction Jet Pump:
The suction jet pump ensures the necessary vacuum in the brake booster so that the braking force is retained for a certain period even after the intake system vacuum depletes. Two non-return valves are integrated in the suction jet pump for brake power assistance.
1. Connection to intake boot
2. Suction jet pump
3. Connection to intake manifold
4. Venturi pipe
5. Connection to brake booster

The suction jet pump works according to the Venturi principle: generation of a pressure difference by increasing the flow speed. This means that the suction jet pump creates a higher vacuum for the brake booster than that already present in the intake system.
 

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#56 · (Edited)
just to add to this post

i saw where the top had come off of the vacuum multiplier. I had this happen to me while changing out my ccv.

in looking closely as to how it is put together...they glued the top where the check valves are... to the body...you can see the red ring is a small amount of glue

without removing it from the car i carefully glued it back together in a similar way....be sure not to put too much on there so none gets on the check valves.
just around the edge...then seal the top with a thin layer around the edges.

it is stronger than it was before and sealed better around the top.

I carefully scraped the old glue off until i liked the fit....it fits in there very snug almost like it would have sealed without being glued. keep in mind you should test fit it a couple of times in there before you use the glue....it can only go in 1 way...it cannot be turned clock or counter clockwise in the housing and the glue dries withing 5 minutes. it was a 2 part epoxy plastic adhesive....

when i priced this part is was over $100 and included the vacuum lines. The glue was $8 plastic glue from autozone.....i did smoke test for vacuum leaks....non found
 
#58 ·
For the record, today I decided to clean my ICV and in order to get to the clamp bolts for the boot over the ICV, I had to disconnect the Torx holding the sucking jet pump venturi valve to the M54 engine.

Here's a picture for your edification:
 

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#60 ·
I was looking for a picture for another user's question when I ran into this nice photo by Michel showing the 2002 525i SJP in situ.

In the picture below you will see the ICV behind the DISA valve. On the left side you will see the electrical connector and on the right side the pipe that leads into the intake elbow is the other reference.
 

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#61 ·
For the crosslinked record, this useful information was posted today:

Hello, I need to buy a sucking jet pump for my 2001 540i. I found it on Amazon. Is this a safe site to purchas this part? Or does anyone know where I can buy this at? Thank You guys.
Sounds like you're looking for 11611440135, I have it available HERE. Below is a photo of the pump for reference.


We just launched USPS and FedEx shipping, majority of parts can now be shipped for a lot less than they use to.
 
#62 ·
For the record, the SJP 'might' be implicated in Poolman's situation today:

The cars brakes act funny from time to time--sometimes when I get on them with light pressure the pedal seems like it goes unexpectedly down about a 1/4 inch and the car brakes hard when this happens--but it's only happened a few times over the last 6 months since these lights have been on--that is the reason I'm thinking it's the pressure sensor
The pedal isn't hard to the feel--when I stated that the pedal fell 1/4 inch it fell and the cars brake came on to stop the car hard--as if I had layed down on them somewhat--
I have replaced two of the wheel sensors and have two that haven't been replaced--still have the ones that I remove, one from the front and one from the back. Thinking about using those on the other side and see if it changes anything. The lights will come on for a moment then go away and do that all day long. Sometimes when the weather is with high humidity the lights will stay on for an hour or so --don't know what to think--it's getting warmer here now--that will give me a chance to look more into the cause's.
Poolman-I would also inspect the suction jet pump. That is the Venturi device that's plugged into the intake tube at the F connector. The thin hose is a vent for the fuel pressure regulator. The thicker hose goes to the suction jet pump that increases vacuum (above manifold vacuum) to the brake booster. If any of the hoses are split, if the device is cracked or damaged or if the vac hose to the IM is not attached, etc., you would have these symptoms.
 
#64 ·
This related question was asked today ...

I'm working on changing the valley pan gasket and ccv and while I was removing the vacuum tube that connects to the back of the ccv, the hard plastic T came apart. It is part number one in this picture.

http://www.realoem.com/bmw/showparts.do?model=DN63&mospid=47588&btnr=11_2675&hg=11&fg=45

I see what looks like an o-ring and I'm assuming this seal is supposed to seal the pipe, but it does not seem to hold together very well.

I think I should buy a new one but do not want to spend $35 if I don't need to.
That part is used for getting vacuum to the brake booster.
You can try super gluing it back together or buy a new part. The new part will last a long time.
The bigger question is do you trust gluing it back together?
 

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#65 ·
This related thread was opened today ...
> E39 (1997 - 2003) > Jet Suck Pump, Vac Leak
There was an older thread that popped here a few days ago. In the thread I noticed the jet suction pump was a two piece devise. The top can come off and that is where the parts are hooked together. Started thinking about that thread over the weekend, and thought, why not give the top a bit of gasket sealer around the creases in the spot where the parts come together. Now I had no cell lights or anything showing I had a vac leak anywhere, but when coming to a stop sign, I would get a bit of a whine from my brakes from time to time. I sealed the parts together yesterday, let it set up over night and drove off on a biz call today.
Car seemed stronger in high gear going up the mountians,,average mileage went up after the first 30 miles of my 160 mile trip. Gas mileage there was 33,,and round trip was 31.
The big thing was, I never hear a single peep out of the brakes all day long. There wasn't a major leak here,, but every little bit you can seal off helps,,there are so many spots that you have to take care of with these cars anyway,,but that's another reason. I try to point them out.
Hope That Helps Someone
3000140 k MILES AS OF TODAY. :thumbup:
 
#66 ·
Guys, I've been looking for info on the Sucking Jet Pump for a while so thanks for a great thread and discussion.

Question, the S54 engine has a SJP that has an inline electrically activated check valve and the connector hooks up to the engine harness. Does anyone know the operation of this check valve, as in when it turns on/off.

Thanks.
 
#67 · (Edited)
iM fimilure with the s54, but your saying it has a Suckjet that has a connector for a electrical input?

any thing thats gonna switch depending on vacuum or positive pressure, will probably run off or throttle percentage and ambient air pressure
 
#68 ·
Replacing SJP "with" bottom hose to manifold too, is a PAIN in the butt! While CCV is not too bad, just time consuming, this is several times worse! It'd be a super simple job (after removing throttle body) "if" there wasn't a hose clamp buried behind the manifold where the TB came off. It's all in the blind work and nearly impossible to get clamp off. New hose likely would have enough grip to hold vacuum so I'm not worried about that. But I've been trying to get the clamp off for two hours so far. Yeah I could have just put new SJP with old hose, but what good is that really on a 15 YO car. I think it would be easier just to remove the intake manifold (seriously).
 
#70 ·
The vacuum hose goes to a fitting under the manifold. Like the jet pump end, there is a permanent, reliable crimp band holding the hose to the fitting.

I believe that the crimp bands were not just for assembly convenience. The brake booster vacuum is a safety item, and the crimp bands are less likely than screw bands to work loose or be accidentally removed.

When I remove the intake manifold I go to the extra effort to detach the vacuum hose from the booster, leaving the rest of the assembly attached with the factory crimps. When I strip down the manifold this is the only thing I don't remove.

In your case, where something will need to be cut for the repair, I would leave the hidden manifold end of the hose attached with the factory crimp band. Pry apart the band at the jet pump and connect the replacement there.
 
#72 ·
ref: Could this "sucking jet pump" be a possible cause of a P0174 code (Running lean on bank x)?

Late 1999 E-39 528i m52tu owners might see INPA Code 127 . I'll testify to that after trouble shooting other "LACK OF VACUUM" issues for the last month and a half. INPA describes this in the error message: "activate solenoid valve socking (suction) jet pump" The german to english description may please some...not me.

I couldn't find a cross-over for P-codes.

ron_of_ orange sept 23, 2018 2:30pm pst
 
#73 · (Edited)
ref: Could this "sucking jet pump" be a possible cause of a P0174 code (Running lean on bank x)?

Late 1999 E-39 528i m52tu owners might see INPA Code 127 . I'll testify to that after trouble shooting other "LACK OF VACUUM" issues for the last month and a half. INPA describes this in the error message: "activate solenoid valve socking (suction) jet pump" The german to english description may please some...not me.

I couldn't find a cross-over for P-codes.

ron_of_ orange sept 23, 2018 2:30pm pst
You should have started a new thread.

There are 2 different Jet Pumps.

One is in the fuel pump system as seen here, Sucking Jet Pump.
https://www.turnermotorsport.com/p-19436-16116752839-genuine-bmw-part/

The other is part of the brake booster vacuum system as seen here, Suction Jet Pump.
https://www.bimmerfest.com/forums/showthread.php?t=578766

You are most likely looking at a low fuel pressure situation, check fuel pressure. 50 psi is good. If pressure is low then code p0174 can result, lean fuel condition, fuel pump etc.

Check your engine for vacuum 18-20hg is good. A vacuum leak in the brake booster vacuum line or the (Suction Jet Pump) can cause a lean condition and throw that code as well.
 
#74 ·
I have only 1 valve from break booster to a funny looking 3 piece valve connector that goes straight to intake tube and directly into pcv I’m beginning to think that my problem lies somewhere within the breakbooster and pcv the sjp there referring to isn’t the big air phmp under the drivers side front bumper is it


Sent from my iPhone using Bimmerfest
 
#77 ·
I found a photo of M54 intake manifold on ebay.
I am posting the pic so everyone knows where the SJP's hose ends (see YELLOW arrows).
It is inward of the metal bracket, once the bracket is out, then you should be able to replace it without removing the I.M.

Auto part Engine Automotive engine part Carburetor Vehicle
 
#79 ·
Wow, this thread started on 11/11/2011 – 9 years ago – but still no definitive answer on the air flow direction through the SJP device. It has 3 ports:
  1. Top to brake booster
  2. Bottom to intake manifold after throttle valve
  3. Side to the F connector after MAF sensor

The intake manifold hose has more negative pressure when the throttle is closed, and this hose helps to evacuate the brake booster via check valve #2. But at wide open throttle there is less negative pressure and this is the reason for the hose from the F connector, as below.

The F connector hose is supplying air for the venturi which creates lower pressure as air flows fast through the narrow path of the venturi during larger throttle open. The lower pressure at the venturi acts like a small vacuum pump to evacuate the brake booster via check valve #1. This path is less dominant during idling as less air moving pass the venturi.

So this is the reason why the valve has 2 paths and 2 check valves, and this is just my logical reasoning.

I stumbled into this thread while looking for answer on how to disconnect the vacuum hose (#1 on the SJP above) from the brake boot without removing the factory one-time-use clamp on the plastic connector. I want to pull this connector off the booster instead of the pulling the hose off the connector which has sharp barbs. Can someone confirm that it’s safe to pull the connector off the booster?
 
#80 ·
Did it yesterday with a pry bar while replacing the brake master cylinder in my son’s ‘99 with the M54. It isnt easy and could result in broken parts, that are old.

This SJP dates way back to M20 days too. My e30 developed a vac leak in the check valve to the booster, and there is a Venturi device in there as well.
 
#81 ·
I have a question, does it matter which "SJP" I'am using ? Like I have a M62 Engine, and I broke one of the plastic pieces on the "SJP" & I ordered a new one off amazon, and seeing that the routing of the hoses that came with the new one is intended for the non v8 model, but the actual "SJP" side by side with the old one looks pretty much identical. So what I did was just cut up the hosing i needed in order for it to fit right going to the rear of the PCV System, and the Intake system, and the Brake Booster System. I read all over through this thread to see if there was a difference in between the v6/v8 but couldn't find an answer. Thanks!
 
#82 ·
If your brakes are working fine your probably OK. Same amount of foot pressure to stop the car??
Got a link to the part you bought?
 
#83 ·
Yes same amount of foot pressure when stopping the car. So I figured I'm good there. I went ahead and Replaced the brake booster hose line from the firewall all the way to the actual fitting itself and seems to be good .
Btw, here is a link to the SJP or Valve I ordered.
 
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