P0087 Low fuel pressure Help!

[mdeneso]

I started my car after work and it took a few seconds longer to start than normal, then it stuttered for a second. After that initial start up all was fine. I drove the 25 miles back to my house and didn't notice any difference in drivability or power. When I got home I noticed a CEL and started the car again, had the same slow start. Scanned the car and got a P0087 Fuel Rail/System pressure too low.

I am thinking the problem is the lpfp, mainly from the slow start symptom. Any other ideas on what it may be? I'm taking in to the dealer in the morning, will follow up with more info. Thanks


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[sonic32]

I've had the same problem but I'm running e85 mix and I have a new lpfp


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[mdeneso]

I've had the same problem but I'm running e85 mix and I have a new lpfp


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I am not running any e85, but did the lpfp fix the problem or is it still occurring with a new pump? I'm a little confused.


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[esimp2k]

I don't recall the code but I just had similar problem and it was the hpfp.


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[TexasDfwS4]

I've had the same problem but I'm running e85 mix and I have a new lpfp

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Same here, to much e85..

You might have gotten bad fuel, burn that tank and refuel and clear the code.

[GRUMPY-S4]

I have had this code when running E85 and it was my HPFP. The Auto-Tech upgrade took two tries before it was right. Looks like the first time around something was off on the machining of the piston.

[damnbiker]

when I got that code on my 2011 A3, the car also went into limp mode. The HPFP had disintegrated itself...luckily with no other damage. The car was still driveable using the LPFP only, but no boost and felt like 50hp. Doesn't sound like your situation is as bad.

[mdeneso]

Started slow again this morning, no power issues on the way to the dealer. It feels fine throughout the rpm range, only symptom right now is the slow start. Should hear back from the dealer soon. I will update this post with the solution in case anyone else has the same issue.


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[LittleDozer]

That code is not a LPFP code. LPFP would be P310B "Fuel pressure out of spec - low pressure fuel system." Your code is likely related to your HPFP and it needs replacing.

[mdeneso]

That code is not a LPFP code. LPFP would be P310B "Fuel pressure out of spec - low pressure fuel system." Your code is likely related to your HPFP and it needs replacing.

Ok, hopefully hear back from the dealer soon. Do you have an idea on what the replacement time is for that? I thought I read that the charger has to be removed.


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[LittleDozer]

Ok, hopefully hear back from the dealer soon. Do you have an idea on what the replacement time is for that? I thought I read that the charger has to be removed.


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1 hour tops. You can see it in front and upper area of engine. Once the car is depressurized (which is super easy to do) it's just a few hoses/clamps/bolts that need to be pulled.


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[esimp2k]

I believe the book price on the hpfp replacement is around $1100


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[LittleDozer]

I believe the book price on the hpfp replacement is around $1100


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If someone pays this they got effed. In no world would it cost that much. Most anyone should pay is $500 if that.


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[esimp2k]

I didn't say it was worth it. I said I think that's what the book value is as OP said it was at a dealer.


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[sonic32]

Even with the new lpfp I still get slow starts but like I said mine i bet is from e85. Doesn't matter how much I run anymore, even if I drop the mixture still slow start, I think I already messed up the hpfp. I'll grab an auto tech rebuild kit and be ready for full e85


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[mdeneso]

So the dealer wants to "start" by replacing both pressure sensors and is going to charge $1200 for that. So I will probably just pick it up and try and figure it out myself.


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[mdeneso]

For an update in case anyone runs into a similar problem in the future, they replaced the high and low pressure sensors and it seems to have solved my problem. I drove it for about 20 miles today and it seems all is well now. The sensors were sending wrong signals to the pumps causing incorrect pressure values. The charger had to be removed to gain access to the high sensor.


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[LittleDozer]

For an update in case anyone runs into a similar problem in the future, they replaced the high and low pressure sensors and it seems to have solved my problem. I drove it for about 20 miles today and it seems all is well now. The sensors were sending wrong signals to the pumps causing incorrect pressure values. The charger had to be removed to gain access to the high sensor.


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Do you have a part number for the high sensor? I thought the only sensor was attached to the HPFP but there's also one on the rail under the charger?


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[mdeneso]

Do you have a part number for the high sensor? I thought the only sensor was attached to the HPFP but there's also one on the rail under the charger?


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I can try and dig out the work order from the dealer to see if they listed a part number.


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[endree]

1 hour tops. You can see it in front and upper area of engine. Once the car is depressurized (which is super easy to do) it's just a few hoses/clamps/bolts that need to be pulled.


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Hi LittleDozer - How do you depressurize the the system? I need to change the HPFP on my B8 S4 and I'm just waiting for the HPFP to come in. But I cannot find a good description anywhere on depressurizing the system. However, I found steps for the rest of the process. Any help would be greatly appreciated!

[LittleDozer]

Hi LittleDozer - How do you depressurize the the system? I need to change the HPFP on my B8 S4 and I'm just waiting for the HPFP to come in. But I cannot find a good description anywhere on depressurizing the system. However, I found steps for the rest of the process. Any help would be greatly appreciated!

You need to pull the fuse on the driver side fuse box. It's a panel between the drivers dash and the door. I think the fuse has a #5 on it. The owners manual has an area that tells you.

After the fuse is pulled just run the car until it dies.

Recently I've just been doing it the ratchet way and twist the metal lug that holds the rail to the HPFP. If you do it just enough in a well ventilated area it'll slowly blow off the pressure.


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[Hofahome]

You need to pull the fuse on the driver side fuse box. It's a panel between the drivers dash and the door. I think the fuse has a #5 on it. The owners manual has an area that tells you.

After the fuse is pulled just run the car until it dies.

Recently I've just been doing it the ratchet way and twist the metal lug that holds the rail to the HPFP. If you do it just enough in a well ventilated area it'll slowly blow off the pressure.


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This. Done it myself.

[endree]

You need to pull the fuse on the driver side fuse box. It's a panel between the drivers dash and the door. I think the fuse has a #5 on it. The owners manual has an area that tells you.

After the fuse is pulled just run the car until it dies.

Recently I've just been doing it the ratchet way and twist the metal lug that holds the rail to the HPFP. If you do it just enough in a well ventilated area it'll slowly blow off the pressure.


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Thank you very much for the tips! I was going to twist the metal lug, but I was worried it is so pressurized that I would break something. So I guess I will try the fuse method as I was going to remove that fuse first anyway. Is it true that you you need a 6mm hex bit (flat end) to get the 2 bolts off that hold the HPFP in place? Thanks again for your help. I am having issues with fuel pressure bleeding off as the car sits. It isn't enough to set off a CEL, but it's enough to make the car take longer than normal to start than stumble for a second, after the car sits for several hours. After that, it runs fine. I am really hoping it isn't that sensor/valve under the blower... Taking a gamble by just changing the HPFP. I really don't feel like removing the blower, especially as I can't find a decent DIY on that. Anyway, I hope to do a write up after I fix the problem. Crossing fingers.

Thanks again!

[jachien]

Thank you very much for the tips! I was going to twist the metal lug, but I was worried it is so pressurized that I would break something. So I guess I will try the fuse method as I was going to remove that fuse first anyway. Is it true that you you need a 6mm hex bit (flat end) to get the 2 bolts off that hold the HPFP in place? Thanks again for your help. I am having issues with fuel pressure bleeding off as the car sits. It isn't enough to set off a CEL, but it's enough to make the car take longer than normal to start than stumble for a second, after the car sits for several hours. After that, it runs fine. I am really hoping it isn't that sensor/valve under the blower... Taking a gamble by just changing the HPFP. I really don't feel like removing the blower, especially as I can't find a decent DIY on that. Anyway, I hope to do a write up after I fix the problem. Crossing fingers.

Thanks again!

Any follow up to this? I just got this code and only this code. But I've already upgraded to the auto tech hpfp to run full e85 fuel. I have a feeling it might be that. However there's another thread where someone mentioned they turned on the AC when it just got hot out. That just happened right now before I got the cel... rather interesting... torque app doesn't mention anything about AC though.


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[Jv218]

Any follow up to this? I just got this code and only this code. But I've already upgraded to the auto tech hpfp to run full e85 fuel. I have a feeling it might be that. However there's another thread where someone mentioned they turned on the AC when it just got hot out. That just happened right now before I got the cel... rather interesting... torque app doesn't mention anything about AC though.


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second this also got this code but disappeared after getting it scanned via auto zone and has not come back since. Car drives fine

[LittleDozer]

Any follow up to this? I just got this code and only this code. But I've already upgraded to the auto tech hpfp to run full e85 fuel. I have a feeling it might be that. However there's another thread where someone mentioned they turned on the AC when it just got hot out. That just happened right now before I got the cel... rather interesting... torque app doesn't mention anything about AC though.


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P310B is related to the low pressure ( in tank) fuel pump, not the high pressure pump. An Autotech upgrade won't stop this code from popping up.

[jachien]

P310B is related to the low pressure ( in tank) fuel pump, not the high pressure pump. An Autotech upgrade won't stop this code from popping up.

Honestly I really didn't think this code is hpfp related but many posts seem to believe so. I actually have the p310b committed to memory since I haven't upgraded to the flex fuel pump yet that I know you and a couple others have done so already... I'm just waiting for that code to pop up eventually.

Torque doesn't actually say anything about fuel pressure. The app says drivetrain fault and that's it really. I know sometimes the code that pops up might be manufacturer specific instead of the general obd2 codes torque is based off of. But anyway... car runs fine it seems. Actually I did a wot 3rd and 4th gear pull just now and didn't get any sputtering. Lol. This car is like a woman sometimes...


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