LPFP (in-tank fuel pump) failure info

**shiro1745** · 12-26-2012 08:38 PM

I found this video posted by Ross-Tech as a confirmation that the LPFP duty cycle should be below 70% at idle with a warmed up engine. So basically everything above 70% should raise questions.

Here is the info attached to the video:
"MVB 103.1 is the low side fuel pressure coming from the lift pump in the fuel tank. MVB 106.2 is the duty cycle the lift pump is being operated at to maintain the correct low side fuel pressure. MVB 106.2 should be below 70% at idle with engine up to temp.

When I pinch off the fuel supply line, my fuel pressure drops down and the ECM ramps up the duty cycle for the lift pump to try and maintain pressure. I did flag the P310B/012555 because of this.

We see the P310B/012555 issue on higher mileage vehicles. I would suggest to inspect the fuel line to make sure there are no kinks or restrictions, if good, then replace the fuel filter and recheck your values. If the readings are still out of spec, then you could have a failing lift pump in the fuel tank."

**mec** · 12-26-2012 08:53 PM

wow very nice info! good find

**seal66** · 12-27-2012 05:13 AM

Ya I was wondering about his. Cause with the dw301 installed in johns car we were still readi above 70% but I think on the aftermarket pump it has a higher duty cycle. Are stock pumps for sure should be below 70%. Seems like above that at idle and people have issues.

Thanks for the great info shiro! Now get that car runnin right and dyno the sucker.

**shiro1745** · 12-27-2012 05:34 AM

That's weird. I thought having a higher flow pump should bring the duty cycle down. ^this pump flows more than oem, right? What low pressure are you reading at idle with the new pump?

**seal66** · 12-27-2012 05:53 AM

Originally Posted by shiro1745

That's weird. I thought having a higher flow pump should bring the duty cycle down. ^this pump flows more than oem, right? What low pressure are you reading at idle with the new pump?

Ya I thought the same thing too. Oh ya it flows way more than stock. AT idle it was reading 5Bar. Granted we did clear all fuel trim logs and readapted it to stock fuel mapping. Gonna give it one or two days then vag it again and see what it looks like. What we saw was 74% duty cycle at idle with 5 bar pressure after adaption to stock maps and only like 2 hrs after installation.

**shiro1745** · 12-27-2012 06:45 AM

Than doesn't make much sense

**seal66** · 12-27-2012 07:00 AM

Ya I know. Lol. Waiting to vag it again and see what's up

**jimrobbington** · 12-28-2012 06:13 AM

Goddamn it Tammy! Eat a dick!

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**jimrobbington** · 12-28-2012 09:18 AM

Originally Posted by shiro1745

Than doesn't make much sense

It doesn't make much sense. Lol. But the verdict is in. This completely, 100%, improved performance across the board. I have all lost boost back, power delivery is more linear, power comes on harder, faster, low speed/rpm driving is much smoother, rev matching down shifts are smoother. I can hit 23-24 psi in every gear now, where before, I was lucky to hit 20, and 18-19 was more common. The all or nothing gas pedal is gone, and I now have mid range. Also, before, when I was at half throttle in the higher rpms, and went wot, nothing else happened. Now I have acceleration there when I do the same. Overall very happy.

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**seal66** · 12-28-2012 09:24 AM

Jim good to hear everything is going good so far. Let me know when you wanna take logs and check the pump out on vagcom

**jimrobbington** · 12-28-2012 09:30 AM

Originally Posted by seal66

Jim good to hear everything is going good so far. Let me know when you wanna take logs and check the pump out on vagcom

Yeah, I'm thinking Monday if you've got time?

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**DRAKLORE** · 12-28-2012 09:40 AM

Awesome news

**seal66** · 12-28-2012 09:43 AM

Originally Posted by jimrobbington

Yeah, I'm thinking Monday if you've got time?

Sent from my porcelain throne.

Yep monday is cool with me

**slvrb7** · 12-28-2012 10:05 AM

I'll see you guys Monday... Jk wish I could drive out that way.

**seal66** · 12-28-2012 10:08 AM

Originally Posted by slvrb7

I'll see you guys Monday... Jk wish I could drive out that way.

Do it. It only takes what 15hrs lol

**mec** · 12-28-2012 10:09 AM

Time for some hpfp upgrade and meth, what else can you possibly add without going stage 3? you're like $800 bucks until you tap out your car and need a new turbo/rods

**seal66** · 12-28-2012 10:11 AM

Originally Posted by mec

Time for some hpfp upgrade and meth, what else can you possibly add without going stage 3? you're like $800 bucks until you tap out your car and need a new turbo/rods

I should throw my HPFP in for some fun. But, still waiting on my intercooler to get back from the powder coater. I really need to install my meth kit

**mec** · 12-28-2012 10:13 AM

You have a bmp too don't you? We should install them together, I have no clue where to even begin lol

**seal66** · 12-28-2012 10:16 AM

Originally Posted by mec

You have a bmp too don't you? We should install them together, I have no clue where to even begin lol

Ya I bought the bmp+ kit which included the W/M kit

**jimrobbington** · 12-28-2012 11:30 AM

Yeah, hpfp will be my next mod if ever I can afford it. Then meth. Then I'm done.

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**shiro1745** · 12-28-2012 04:59 PM

"Then I'm done" hahaha

**dalmation53** · 09-22-2018 07:31 PM

Originally Posted by jimrobbington

It doesn't make much sense. Lol. But the verdict is in. This completely, 100%, improved performance across the board. I have all lost boost back, power delivery is more linear, power comes on harder, faster, low speed/rpm driving is much smoother, rev matching down shifts are smoother. I can hit 23-24 psi in every gear now, where before, I was lucky to hit 20, and 18-19 was more common. The all or nothing gas pedal is gone, and I now have mid range. Also, before, when I was at half throttle in the higher rpms, and went wot, nothing else happened. Now I have acceleration there when I do the same. Overall very happy.

Sent from my porcelain throne.

Holy thread revival so were you getting fuel cuts as well?

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**jimrobbington** · 09-22-2018 07:49 PM

Originally Posted by dalmation53

Holy thread revival so were you getting fuel cuts as well?

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I'm having a really hard time recalling the context of my post. Lol. I did have some fuel cut issues, but after going through 3 lpfps, came to the conclusion there was dirt/ sediment in my fuel tank that was burning up fuel pumps. Had the tank cleaned out and solved my problems.

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**dalmation53** · 09-22-2018 07:50 PM

Originally Posted by jimrobbington

I'm having a really hard time recalling the context of my post. Lol. I did have some fuel cut issues, but after going through 3 lpfps, came to the conclusion there was dirt/ sediment in my fuel tank that was burning up fuel pumps. Had the tank cleaned out and solved my problems.

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I'm asking because my car is having fuel cuts as well and have a code for the low pressure fuel pump and needed to know symptoms before k throw a new one in there.

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**jimrobbington** · 09-22-2018 07:59 PM

Originally Posted by dalmation53

I'm asking because my car is having fuel cuts as well and have a code for the low pressure fuel pump and needed to know symptoms before k throw a new one in there.

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Iirc, I was having power hiccups under full load, peak boost, full throttle situations.

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**dalmation53** · 09-22-2018 08:02 PM

Originally Posted by jimrobbington

Iirc, I was having power hiccups under full load, peak boost, full throttle situations.

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Yessssss sameee here man. Driving normally is fine but i'm having what your saying. I will just replace thr lpfp and see whats up. After yoi replaced yours it was fine after?

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**jimrobbington** · 09-22-2018 08:27 PM

Originally Posted by dalmation53

Yessssss sameee here man. Driving normally is fine but i'm having what your saying. I will just replace thr lpfp and see whats up. After yoi replaced yours it was fine after?

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Like I said, I sent through 3 lpfps before finding the cause of the problem. I think mine was a rare case though.

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**K1196A** · 09-24-2018 12:34 PM

Originally Posted by dalmation53

Yessssss sameee here man. Driving normally is fine but i'm having what your saying. I will just replace thr lpfp and see whats up. After yoi replaced yours it was fine after?

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Had the same issue. did the pump and filter. no problems since.

**dalmation53** · 09-28-2018 08:12 PM

Originally Posted by jimrobbington

Like I said, I sent through 3 lpfps before finding the cause of the problem. I think mine was a rare case though.

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Fixed my problem. It was LPFP

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