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-   -   Sucking jet pump? (http://forum.e46fanatics.com/showthread.php?t=523763)

ssm1991 11-21-2007 02:17 PM

Sucking jet pump?
 
1 Attachment(s)
Anyone knows what the "SUCKING JET PUMP" in the RealOEM image below does?

I'm trying to diagnose a lean mixture problem on acceleration, possibly caused by a vacuum leak or a defective fuel regulator/filter (had it changed 9 months ago).

The "SUPPORT" connector is actually F-shaped:
- the bottom connects to the intake elbow right after the MAF
- the top goes to the "SUCKING JET PUMP"
- a third narrower one connects to the fuel regulator/filter, presumably to adjust the fuel pressure depending on the intake pressure. The SUPPORT is however connected between the throttle and the MAF, so I'm not sure how much it affects fuel pressure.

http://forum.e46fanatics.com/attachm...1&d=1195676176

S716A 11-21-2007 05:18 PM

Sure thing. The "Sucking Jet Pump" is just a poor translation. It's actually the vacuum check valve for the power brake booster.

Commander FAT 11-21-2007 05:58 PM

^ Hot damn I was just about to say pretty much the same thing.

ssm1991 11-21-2007 09:10 PM

Thanks, makes sense for the brake booster.

Although I'm still wondering why the fuel regulator/filter vacuum hose is connected to the F-shaped joint (support) which is before the throttle. I actually tested it by disconnecting it from the F-joint and connecting a syringe to it. Increasing the air pressure also increases the fuel pressure.

But the location (before the throttle) makes me wonder if the air pressure variations at that point affect it substantially to make a difference, compared to putting it in the intake manifold after the throttle where the pressures are very different between idle and WOT.


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