Member Since: 14 Apr 2019
Location: Westbury
Posts: 2459
If the volume is good at the filter you may need to fit a genuine filter.
It could also be a kinked fuel line inside or outside the tankAndrew
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22nd Nov 2021 11:33 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4628
There's a lp ITP within the HPFP, if this fails it will cause P0087. In this case it's the lp side feeding the ITP that appears at fault, which will produce P0087 and with this dtc it is usually a fuel supply issue, BUT not always. You have to go through the elimination process otherwise its going to be very expensive guesswork.yµ (idµ - eAµ) ψ=mψ
22nd Nov 2021 11:37 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4628
slider_p wrote:
I just came across the post below, could this be my problem? Or should I probably aim at the electrics side first, maybe make a jump lead to the connector on the fuel tank?
I could also try to unscrew the filter and catch the output straight from the tank
That's on a Euro 3 system with a different filter but you can unplug the line at the back of the housing and test the output from there. I'm inclined to think though you either have something restricting flow, or there's an issue within the tank. The lines have push fit connectors so you should be able to test without too much difficulty. If there's no improvement you're going to have to keep working towards the tank until that flow improves.yµ (idµ - eAµ) ψ=mψ
22nd Nov 2021 11:50 pm
slider_p
Member Since: 22 Dec 2019
Location: Brabant
Posts: 13
Ok I removed the filter and started the pump
1250 ml within 25 seconds
So I think the lpfp is ok. Of course without the resistance of the filter…
I am going to blow the line between the filter and engine with air now and see if that helps…
23rd Nov 2021 9:14 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4628
Better, but still low delivery especially since the filter is out of the way.
The filter shouldn't be making that much difference anyway unless its clogged, faulty, (most unusual for a Mahle), or the fuel lines are wrong way around.?
Edit: Sorry I misread your last post, 1250 ml in 25 secs looks fine. Something wrong between there and the hpfp so. Might be worth considering a new filter if blowing through the lines/cooler doesn't help.yµ (idµ - eAµ) ψ=mψ
23rd Nov 2021 10:06 pm
slider_p
Member Since: 22 Dec 2019
Location: Brabant
Posts: 13
I also blew the lines from the engine to the filter with air. After that I refitted the filter and checked the fuel flow before the schräder valve and both lines together in a bottle resulted in more than 1250 ml in less than 30 seconds.
I think this should be enough?
23rd Nov 2021 11:21 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4628
Yeah that looks much better, did you get a lot of gunk out of the system?yµ (idµ - eAµ) ψ=mψ
24th Nov 2021 12:16 am
slider_p
Member Since: 22 Dec 2019
Location: Brabant
Posts: 13
No not at all, I think measuring through the schräder valve just doesn’t work so well for the flow, only for pressure? The line seemed pretty clean (including the cooler)
Maybe there was no issue in the low pressure fuel system after all… at least I diagnosed thoroughly that the flow is ok and the issue should be either in the volume control valve, mechanical part of the pump (which I can’t really believe) or the common rail pressure sensor.
The latter one is on order and should be here tomorrow…
24th Nov 2021 12:22 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4628
The schrader valve should be very capable of providing the flow for testing, perhaps the connector you are using is not right. You can remove the valve and clamp a suitable length of pipe over the stub. Then you will eliminate the valve.
There is one other test you can do to test the integrity of the HPFP. Once you have reconnected everything and run the engine for a few mins, switch off and pull out the LPFP relay. Start the car and take it for a short drive (bring relay with you )
IF the HPFP is OK the car should drive normally, BUT only if the low pressure side is without any restriction!! If you go into limp and you know for certain the lp side is good, then the HPFP is failing.
You will get two fault codes during this procedure, one relates to the LPFP "circuit open". The other will be for the fuel rail pressure being too low. Ignore them and clear once you have replaced the relay.
You therefore need to confirm without doubt that the correct flow/pressure is available at the schrader before doing this test. Otherwise it's a waste of time! yµ (idµ - eAµ) ψ=mψ
24th Nov 2021 12:38 am
slider_p
Member Since: 22 Dec 2019
Location: Brabant
Posts: 13
Thanks I will do that test and report here! I have the idea that you really know what you are talking about thanks for all your help.
24th Nov 2021 9:28 am
bensla
Member Since: 02 May 2023
Location: Trowbridge
Posts: 138
Worth noting I saw a massive restriction to flow unless I removed the valve core. I dropped my tank before figuring this out!
2nd Oct 2023 7:49 am
bensla
Member Since: 02 May 2023
Location: Trowbridge
Posts: 138
slider_p wrote:
Thanks I will do that test and report here! I have the idea that you really know what you are talking about thanks for all your help.
Did you ever conclude this problem? I had repeated P0087 but apparently only in warm weather - at low load/revs. Was thinking I need to change PCV next but you have me worried it won’t fix it now.
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thanks for all your help.
