Hello, guys,

 

Long story short, yesterday I changed fuel filter and in the bottom of the reservoir I found some metal shavings (sorry no photo, forgot to do that). There were not many of them, mostly big, about 3-4 mm in length and narrow. There also was couple smaller ones.  Yeah I know, first suspect is high pressure pump. I was talking to some diesel mechanics about it and some of them told very strange thing. They said, that it could be pump in the fuel tank to blame, I really doubt it and as much as I read about CR fuel systems I heard it first time. Can anyone with real knowledge tell if it is possible to get metal shavings from pump in fuel tank? As I know it is always high pressure pump that gives metal debris, maybe I am wrong. Just want to know. 

 

Car is Skoda Superb 1.6 TDI 88 KW, 2016, 200 000 Km. As I know same CR fuel system goes on all VW EA288 engines. 

 

P.S. it was my first fuel filter change, bought the car half year ago and did it properly with VCDS.  

I thought the high pressure pump was after the fuel filter, it makes very little sense for it to be before.

 

On that basis the debris can only have come from the lift pump, that draws fuel through a guaze filter so it sound like the pump is breaking up.

34 minutes ago, J.R. said:

I thought the high pressure pump was after the fuel filter, it makes very little sense for it to be before.

 

On that basis the debris can only have come from the lift pump, that draws fuel through a guaze filter so it sound like the pump is breaking up.

If the high pressure pump is breaking up, fuel will go via the fuel rail to the return and back to the tank, then will get drawn into the filter that way.

Edited 14 March, 20224 yr by ApertureS

Aha!! - I understand your reasoning.

 

But the tank sender unit has a guaze strainer that would stop any particles of that size surely? And then they would have to go through the lift pump but I reckon they would drop to the bottom of the tank beneath the pick up point, perhaps the smaller particles in suspension that get through damage the lift pump creating the shavings which are in turn trapped in the fuel filter.

 

looks like I was wise to chicken out at 5am Sunday morning from driving the last 50 miles of the 500 mile trip on the reserve capacity! I started with 3/4 of a tank.

Were all the screws from the fuel filter housing cap in good condition? Or would it be possible that these metal shavings be the thread of one of the screws? 

20 hours ago, Bap33 said:

Were all the screws from the fuel filter housing cap in good condition? Or would it be possible that these metal shavings be the thread of one of the screws? 

 

Hey, all screws looks good and tightens as should (But I have not inspected holes for screws). Today I rechecked my fuel filter, all seemed clean. Nothing on filter itself from top or sides. When gave some light into fuel it kinda seemed there are some metal at the bottom, but it could be shining metal from filter housing. All fuel sucked from filter reservoir was clean, but when I cleaned with cloth I noticed one more metal shaving, which do not react to magnet. (added photo). It is kinda big again. I was researching this problem and shavings from HPFP should be more like sand grains (even smaller), so mine metal in fuel kinda does not make any sense. Last time shavings on cloth was even more bigger. I have also lifted pressure sensor from HPFP, all clean there. I have also found mine first fuel from filter reservoir, I have poured it into glass jar. There are some rubbish and maybe couple little metal shavings when I shake it, but it can be air bubbles, it is very hard to judge. When all rubbish sits on bottom I do not see metal, but I had to little time to look at it from different perspectives.

 

I wanted to look at fuel tank, but can not lift back seat, and do not what to brake it. 

 

I was ready to change HPFP, but now I do not know if it is really needed. Guys from Poland sells these Bosch CP4 pumps for 400+. They say it is new, but I think they are renewed, anyway better then used.

 

P.S. After recheck added new filter and primed the system with VCDS

The issue with metal filings being in the fuel system is exactly that, they will be everywhere.

 

If you just change the pump the shavings have every possibility and ive seen it happen on lots of cars where people dont want to pay the money - the shavings eat the new pump to pieces and it doesnt last long at all.

 

The only true solution that will solve the problem 100% is a fuel tank removal and full clean, all the fuel lines cleaned out, fuel filter replaced, fuel pump - both replaced, fuel rail cleaned out, hp fuel lines cleaned out, fuel return valves cleaned/replaced, injectors cleaned/replaced.

 

Basically it gets expensive, all these parts work with tiny tolerances so if there is actually a metal problem, it can easily damage parts.

 

Do you have photos of this metal shavings, they can vary in colour and if they are magnetic or not will help narrow down location of cause. 

4 minutes ago, ApertureS said:

The issue with metal filings being in the fuel system is exactly that, they will be everywhere.

 

If you just change the pump the shavings have every possibility and ive seen it happen on lots of cars where people dont want to pay the money - the shavings eat the new pump to pieces and it doesnt last long at all.

 

The only true solution that will solve the problem 100% is a fuel tank removal and full clean, all the fuel lines cleaned out, fuel filter replaced, fuel pump - both replaced, fuel rail cleaned out, hp fuel lines cleaned out, fuel return valves cleaned/replaced, injectors cleaned/replaced.

 

Basically it gets expensive, all these parts work with tiny tolerances so if there is actually a metal problem, it can easily damage parts.

 

Do you have photos of this metal shavings, they can vary in colour and if they are magnetic or not will help narrow down location of cause. 

 

Yeah, I know that all has to be cleaned when you change the HPFP. When I did my first fuel filter change, I do not know why I have not taken picture of metal shavings and my dad just put filter and main cloth I cleaned it into fire, they are gone. As I mentioned, have the fuel itself, but is tells me not too much. I have put it in the balcony for night as smell is not nice, will try to check it tomorrow and try to take a photo. (it is very hard to make photo that you would see something that small)

 

Thanks for the tips and help.

 

 

On 16/03/2022 at 18:45, katonas said:

 

Yeah, I know that all has to be cleaned when you change the HPFP. When I did my first fuel filter change, I do not know why I have not taken picture of metal shavings and my dad just put filter and main cloth I cleaned it into fire, they are gone. As I mentioned, have the fuel itself, but is tells me not too much. I have put it in the balcony for night as smell is not nice, will try to check it tomorrow and try to take a photo. (it is very hard to make photo that you would see something that small)

 

Thanks for the tips and help.

 

 

How many hoses do you have on the fuel filter ?  Do you have a photo of the engine you can post ?

On 14/03/2022 at 20:55, ApertureS said:

If the high pressure pump is breaking up, fuel will go via the fuel rail to the return and back to the tank, then will get drawn into the filter that way.

I don't think that's quite correct. If it's a 3 hose filter? The HP pump has a return to the fuel tank and the fuel rail returns to the fuel filter.

 

If it's a 4 hose filter everything goes back through the filter. And it has an external LP pump on top of the right hand engine mounting. 

1 hour ago, Derbyshirebod said:

I don't think that's quite correct. If it's a 3 hose filter? The HP pump has a return to the fuel tank and the fuel rail returns to the fuel filter.

 

If it's a 4 hose filter everything goes back through the filter. And it has an external LP pump on top of the right hand engine mounting. 

Whichever setup it is, swarf will most likely go via all the components.

 

if it’s a 3 pipe it will go hp pump return to tank to low pressure pump and filter

or through hp to rail and back into the filter and injectors that way

 

If it’s a 4 hose setup, fuel is still returned to the tank and there’s a very high chance it’s gonna carry metal filings with it, even if it’s a low chance, would you really wanna risk it?

 

I was more talking in a general sense that fuel will and won’t get into small places but if you’re doing all the work correctly, you wouldn’t want to risk it for the cheaper easier stuff that might be unaffected 

9 hours ago, Derbyshirebod said:

How many hoses do you have on the fuel filter ?  Do you have a photo of the engine you can post ?

There are three hoses in the filter, back line goes straight to tank. I have talked to some people about my problem, and all of them say that metal shavings (flakes) from HP pump should be very small, mine are big and not many, like from drilling of some sort. As I do not know what has been done with the car as I have it for half year, for now I will be putting secondary filter on fuel line and will check how the situation is going. It is just to see if there are new metal rubbish or not, and at the same time I will not have to take fuel filter out every time. 

I've been told that when the HP pump fails it's quite often the bearings that start to break up so I guess you could get larger pieces ?

18 hours ago, ApertureS said:

 

If it’s a 4 hose setup, fuel is still returned to the tank and there’s a very high chance it’s gonna carry metal filings with it, even if it’s a low chance, would you really wanna risk it?

 

 

 

I have the 4 hose set up on my car. The fuel is returned into the filter then back to the fuel tank. Why would the returning fuel not be filtered if it's going through the filter? So I can't see how any debris would end up in the fuel tank? Yes I agree that on the 3 hose filter the debris can be returned to the fuel tank. 

After reading about the 3 and 4 hose filters I looked at mine today, - a 4 hose filter.

 

I cannot get my head around how one single filter element can operate filtering fuel flowing in 2 different directions, can anybody enlighten me please?

33 minutes ago, J.R. said:

After reading about the 3 and 4 hose filters I looked at mine today, - a 4 hose filter.

 

I cannot get my head around how one single filter element can operate filtering fuel flowing in 2 different directions, can anybody enlighten me please?

 

Your set up must be like mine the LP electric pump on top of the engine mount draws the fuel up from the tank into and through the fuel filter and then feeds the HP pump. Excess fuel from the HP pump and fuel rail get returned into the fuel bowl which gets filtered and drawn back to the LP pump. Excess pressure/fuel in the filter bowl forces the fuel back out of the fuel tank return. There must be a one way valve in the feed from the fuel tank.