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-   -   FIXED: Return of the P0171 and P0174 (https://xoutpost.com/bmw-sav-forums/x5-e53-forum/93637-fixed-return-p0171-p0174.html)

upallnight 09-13-2013 01:57 PM
Then I don't know what is the problem with your truck.

Like they would say in "SHARK TANK"

I'M OUT......

diddy0071 09-13-2013 02:00 PM
Quote:
Originally Posted by upallnight (Post 955991)
Then I don't know what is the problem with your truck.

Like they would say in "SHARK TANK"

I'M OUT......
Well then thanks and goodbye!

I'll hope nobody else is out, eventually the problem will be solved (I hope!) and then this thread will some day be of use to someone else who is having a hard time.

sunny5280 09-13-2013 02:13 PM
Quote:
Originally Posted by diddy0071 (Post 955992)
Well then thanks and goodbye!

I'll hope nobody else is out, eventually the problem will be solved (I hope!) and then this thread will some day be of use to someone else who is having a hard time.
I just finished watching the video and I'm not really sure what to conclude from it as I don't know what you're testing. A recommendation...walk us through what exactly it is you're doing. Something like "Testing at the fuel rail, vacuum hose disconnected, engine stalls / hesitates when gas peddle pressed quickly". I do see the pressure dropped when you pressed on the gas peddle but I can't tell if the vehicle hesitate or not (I didn't get that impression from the sound of the vehicle). I think it would also be good to know if the pressure drop is normal or unusual. I would think it unusual but I can't be certain as I have no experience in this area.

diddy0071 09-13-2013 02:19 PM
Quote:
Originally Posted by sunny5280 (Post 955994)
I just finished watching the video and I'm not really sure what to conclude from it as I don't know what you're testing. A recommendation...walk us through what exactly it is you're doing. Something like "Testing at the fuel rail, vacuum hose disconnected, engine stalls / hesitates when gas peddle pressed quickly". I do see the pressure dropped when you pressed on the gas peddle but I can't tell if the vehicle hesitate or not (I didn't get that impression from the sound of the vehicle). I think it would also be good to know if the pressure drop is normal or unusual. I would think it unusual but I can't be certain as I have no experience in this area.
The test was checking the pressure with the vacuum line to the FPR on and off. It hesitates if I step on the accelerator too hard.

sunny5280 09-13-2013 02:39 PM
Quote:
Originally Posted by diddy0071 (Post 955996)
The test was checking the pressure with the vacuum line to the FPR on and off. It hesitates if I step on the accelerator too hard.
Would that coincide with the decrease in fuel pressure?

bcredliner 09-13-2013 02:56 PM
:iagree:The result of last nights test indicates a bad fuel regulator.

I am aware I am about to disagree with what I just agreed.

If the regulator is bad it was bad out of the box. That can happen but it certainly is very unusual. In addition, the engine ran fine with the old fuel filter. Further, the original fix was not a new fuel filter. The original fix was a different fuel pump. The pumps could have all gone bad or been bad but what if they weren't?

Each time I mull over your problem from re-reading the summary, even though you inspected the tank and the pickup when you replaced the pump the first time, it keeps popping up in my mind that the problem is coming from the tank and is causing the pump to lose pressure and/or show slow pressure recovery from advancing the throttle. I keep thinking that something keeps partially restricting the fuel getting to the pump, the possibility that the core cause is reoccurring restriction of adequate fuel flow to the pump. There is some endorsement when the problem returns just after gassing up.
_____

diddy0071 09-13-2013 03:14 PM
Quote:
Originally Posted by bcredliner (Post 956003)
:iagree:The result of last nights test indicates a bad fuel regulator.

I am aware I am about to disagree with what I just agreed.

If the regulator is bad it was bad out of the box. That can happen but it certainly is very unusual. In addition, the engine ran fine with the old fuel filter. Further, the original fix was not a new fuel filter. The original fix was a different fuel pump. The pumps could have all gone bad or been bad but what if they weren't?

Each time I mull over your problem from re-reading the summary, even though you inspected the tank and the pickup when you replaced the pump the first time, it keeps popping up in my mind that the problem is coming from the tank and is causing the pump to lose pressure and/or show slow pressure recovery from advancing the throttle. I keep thinking that something keeps partially restricting the fuel getting to the pump, the possibility that the core cause is reoccurring restriction of adequate fuel flow to the pump. There is some endorsement when the problem returns just after gassing up.
_____
It is on it's 3rd fuel pump and 3rd filter/regulator (Counting the original I replaced just because I had replaced the fuel pump the first time around, not that it was failing or doing anything bad). The 2nd filter/regulator didn't fix anything and this 3rd one didn't either.

diddy0071 09-13-2013 03:34 PM
For shits and giggles (and honestly, to stop the voices in my head) let's assume the lines for the fuel filter were swapped, would this cause the issue?

I'm about ready to take that fucker apart (a 3rd fucking time) and swapping the hoses and see what THAT does.

bcredliner 09-13-2013 03:48 PM
Quote:
Originally Posted by diddy0071 (Post 956007)
It is on it's 3rd fuel pump and 3rd filter/regulator (Counting the original I replaced just because I had replaced the fuel pump the first time around, not that it was failing or doing anything bad). The 2nd filter/regulator didn't fix anything and this 3rd one didn't either.
Exactly my point. I'm suggesting we focused on pumps and filters when they were symptoms rather than the core cause.

I think the pumps could get to the proper pressure for the circumstances, they just couldn't or couldn't do so in the proper timeframe. That should mean what you did or didn't do in the first replacement was the done in the opposite fashion the other two times. An indication of restricted fuel flow---when you rev the engine the pressure drops then when it idles the pressure slowly returns to normal. When you turn on the key the pressure is slow getting to normal. When you start the engine the pressure drops rather than staying at normal pressure. The pumps haven't been able to get enough fuel on a continual basis to meet the demand.

I'm suggesting when you changed each pump you removed all or part of the restriction each time--but did not eliminate what is causing the restriction.

If that is not the case, IMO, we need to stop replacing parts and wait until a BMW qualified tech troubleshoots the problem.

bcredliner 09-13-2013 03:56 PM
You could also do a voltage drop test on the pump, that's not hard to do if you have a meter. If the voltage is low the pumps may not have had the power needed to keep up. But, if that were the case the first pump replacement should not have fixed the problem.


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