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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Has anyone had their fuel pump go just after one month of running a tune?



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      07-24-2009, 12:50 AM   #1
Glowin
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Has anyone had their fuel pump go just after one month of running a tune?

Wow, didn't think they crapped out that fast! And especially if you've only put on like 500 miles, and aren't driving super aggressive all the time???
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      07-24-2009, 01:08 AM   #2
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Has nothing to do with the tune, driving, etc... the pumps are dying because they are defective... The majority of them die on 100% stock cars. It's a major problem, and unrelated to the tune, driving, miles, etc. It can happen with 200 miles or 20000 miles. Heck, new cars have pulled off the lot and come right back with a failed pump. Last time I talked to my local dealer, they were doing several replacements a week.
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      07-24-2009, 01:19 AM   #3
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Wow... Guess it's just a coincidence then that it happened one month after being tuned...

I thought I read there is a new version of the pump out there now, that's supposedly improved over the previous version? My car's a May 08 build, so I don't know what version I have.

I did hear though that even 09's pumps are dying, so maybe the pumps they're still using in the newer cars are still the same old version?
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      07-24-2009, 11:51 AM   #4
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This is my understanding :
(I could have a few points wrong)


There are 2 fuel pumps in your car, and one regulator

1) low pressure pump. It pumps fuel from the gas tank to the HPFP. It pumps more fuel as you use more power.

2) High pressure fuel pump (HPFP). This is attached to your engine. It takes fuel pumped from the low pressure pump, and pressurizes it for injection into the cylinders.

[if it is a recirculating type]
*It pumps the same amount all the time, as it's mechanically linked to your RPM, not to any fuel consumption signal*
[else]
*It can pump more fuel if supplied with more. But only up to the capacity of the piston, at which point it is maxxed out, as you can't make it pump faster*

3) High pressure regulator.
[if this is a recirculating system] This device redirects some of the pressurized fuel from the HPFP into your injectors.
The remainder of the fuel re-circulates.
[else]
This allows more low pressure fuel to flow into the high pressure pump.



A tune would :
a) make the pressure regulator allow more fuel to flow out of the HPFP

b) [if re-circulating]have no effect on the HPFP. If anything it would relieve pressure from the pump by allowing more fuel/pressure to escape per injection cycle.
[else] would allow more fuel to enter the HPFP. Each piston stroke of the HPFP would pump more fuel, up to the capacity of the HPFP piston/cylinder.

c) it would require the low pressure pump to work harder to keep the HPFP supplied with fuel, as the regulator allows more fuel to escape from the HPFP.

-scheherazade

Last edited by scheherazade; 07-24-2009 at 04:56 PM.
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      07-24-2009, 12:26 PM   #5
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^^I'm sure you wouldn't heard that from your dealer if they found a tune on your car going into replace a HPFP. lol
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      07-24-2009, 12:26 PM   #6
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scheherazade, if I'm understanding the conclusion to draw from your facts then, you're saying that the HPFP failing is not related to having a tune? (point b) Is that correct?

I got these three codes: 29DC (Cylinder injection switch-off), 2FBF (Fuel Pressure at Injection Release) and 29F2 (Fuel high pressure system, fuel pressure), which I understand both point to the HPFP attached to the engine that's causing issues, correct? (rather than the low pressure pump or the high pressure regulator)

Last edited by Glowin; 07-27-2009 at 02:51 PM.
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      07-24-2009, 04:52 PM   #7
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Quote:
Originally Posted by Glowin View Post
scheherazade, if I'm understanding the conclusion to draw from your facts then, you're saying that the HPFP failing is not related to having a tune? (point b) Is that correct?
I am saying that the HPFP level of usage is controlled by RPM, as it is mechanically linked to the engine.

Unlike an electric low pressure pump which will pump faster to move more fuel, the mechanical HPFP pumps at a fixed rate relative to any given engine RPM.

Now I don't know how this pump works [could be re-circulating, could be non-re-circulating], so the pressure regulator could be in two places :

1) before HPFP, supplying the HPFP with more or less fuel per pump cycle.

2) after HPFP, redirecting a fixed high pressure fuel flow from either a closed loop or to the injectors.

Option 1 could theoretically make the pump work harder, but no faster than it did before.
The piston in the HPFP is a fixed size, and strokes the same amount of times per minute per any given RPM.
You can fill that cylinder with more or less fuel, but you can't fill it with more than it holds.

Someone else would have to chime in with the details.

-scheherazade
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