Ok been having issues with low fuel pressure for a few months van runs fone however intermittently does loose around 300-500psi in fuel pressure. All 4 injectors failed so these were replaced first, 6 weeks later code returned, sensor then replaced, not that, then hpfp replaced, not that, then we have just had the fuel rail and regulator replaced running fine for 160 miles up and down motorway but we have just filled the fuel tank and a mile down the road the code returns!! We now have realised just after replacing the hpfp we filled the engine amd the code came back then too. We only have the lift pump to replace now, could this be failing only when the fuel tank is full? The fuel tank vent doesnt seem blocked so all fingers point to the lift pump, anyone else had a similar experience? Van drives perfect no hard starts etc only thing we notice now and again is high idoling at 1000rpm on the dash
T6 low pressure fuel P0087 code everytime we fill the fuel tank full
- Thread starter gaz_123
- Start date
UPDATE - the whole of the fuel system has been replaced including the fuel tank, lpfp, hpfp, fuel rail, fuel regulator, fuel pressure sensor, fuel filter, all 4 injectors due to fuel contamination and swarf being present in fuel tank and still the p0087 code! Scan is still showing 300-400 loss in fuel pressure however van drives perfect, seems to throw the fault code every 150 miles when going around 60-70mph. The van was remapped prior to our ownership so unsure how well thats been done so at this monent in time the remap is being reversed back to factory settings, fingers crossed as we are £6.6k down and still no solution!!
Onidlanor77
New Member
I have exactly what you going through i did test lift pump in tank not , it's aftermarket but based on vw repair manual it passes all tests but i can not see more than 3 bars from supply pump in tank it should be 4.5 according vw .But when I restrict fuel return pipe than my pressure is exactly 4.5 on idle so I am thinking, maybe there is problem with check valve in hpfp ?
our hpfp has been replaced along with the whole fuel system now, including low lift pump eyc. we have rooted the cause down to everytime it attempts to do a dof regen it gets 7 mins in and then the p0087 code appears, in the garage at the moment investigating the wiring as we have replaced everything in the fuel system so we know its nothing in there
Brand new VW OEM injectors?
Has the return flow from the injectors been tested - in situ?
ANOTHER UPDATE*** whole fuel system now replaced how ever we now have a reader, van has been low on fuel all week so filled it again, shortly up the road van goes in to high revs, reader states its in active regen, so when we get on a faster road i out my foot down and straight away the p0087 code returns, van into limp mode and regen stops. Now and again along with the p0087 code we get a low voltage code p0562 so we have been monitoring the voltage, fuel pressure and regen at the time the fault kicked in. I will add the graphs below but excuse the number as the app we are using will only let us display 2 things against each other
Does anyone think the intermittent voltage dropped is happening first from these graphs? Or is it impossible to tell? Only the p0562 code comes on sometimes with the p0087 code and when this happend last week the low voltage didnt come on at all. To add at no time has any dpf code come on
Onidlanor77
New Member
What is pressure before and after fuel filter,you can have slow in tank pump.Or fuel regulator or injector is leaking.Your engine is starving for fuel under load that's why you go to limp mode
all the fuel system is new including all pumps and injectors, pressures are fine until the van is in active regen and only when the van is in active regen, we are thinking it may be an electrical gremlin causing all this related to the dpf regen but unsure if the graphs show the voltage dropping first to trigger the rest?
Onidlanor77
New Member
Test drive car with fuel gauge on window and watch for pressure drop.Did you do woltage drop test on fuel pump in tank maybe it's wiring i had 570mA (0.5V is max allowed) drop on positive wire so I did replace wire with thicker and now it's 400mA drop.Gained 0.3bar pressure i did replace section above tank only if I do it from tank to relay i believe that i can improve pressure by another 0.5bar
Its currently in the garage and early next week they are looking at the wiring for corrosion so hopefully something comes up with that as we are all out of ideas
Onidlanor77
New Member
I should have 4.5bar cxfa engine when idling i had all new parts fitted last year but hpfp was rebuilt and if i block return flow pipe to tank in have pressure exactly 4.5bar on idle so my suspicion is in my case check valve in hpfp which is opening early and not letting fuel pump in tank to build sufficient pressure i have now 3.1 bar pressure and not limp mode happens yet but it was regular on 2.6bar
Onidlanor77
New Member
Update hpfp and injectors checked, no problem found so now only option left is upgrade wiring to decrease resistance close to zero as possible, will do it after winter
natho141414
New Member
I’m having this type of problem when Drving over 2 hours I keep cutting out showing this code