MP9 Dreaded Fuel Rail (Return completely blocked)

[sophiawright]

Good day fellow VW owners.

I have had the craziest ride with this fuel issue now for.....yes years.
Car: 2003 VW Citi Life 1.6 MP9 (Branch . SS DeGraaff exuahst) and that's it.

It first started with the fuel pump making some heavy noises when running for a long time, under some pretty high temps (30+) and with the aircon on.
Later it really got me stuck Running out of power) with some debris in the fuel filter (Yes the car was standing also for some time) and was fixed by replacing it, worked fine. Then another time completely got stuck next to the road with yet again the same issue. Now it's starting to do this "fuel starvation" thing again but here is the very interesting bit.....

Obviously the fuel pressure is so high that the fuel pump can barely pump more, the return pipe from the fuel rail does not even have a drop coming out of it. I replaced the fuel rial pressure regulator...not cheap and that still did not remedy the problem. The old one actually functions, you can hear the diaphragm move as vacuum is placed on it. The replacement the same but nothing coming out.

Fuel rail is not broken, wish it was but somehow the return is completely either gunked up or clogged by something, who knows what, the return rubber pipe seems to be ok and not "snotty" so it's not rubber that is in there, for what we know right now.

Anyway, long story short, I have had it with these crappy aftermarket fuel rail regulators and it's expensive (R400+ for a tiny thing) and inferior. I was wondering if anyone had success with an adjustable aftermarket fuel regulator setup like those you get as an external with a gauge on it.

My biggest issue now is the fact that they all operate in a way which is going to be tricky for me, since if you have a broken fuel rail, you place the inlet into the rail, then to the regulator and the return just runs no issues, but since I have no return I must put the fuel rail on the same line (T Pipe) with my fuel regulator's inlet which could lead to some slight fuel starvation if the rail cannot get the fuel in time <- debatable since the pressure is 4 bar at the rail and 5 from the pump.

!!!EDIT!!! Quick update on what was done:
* Before it all, the pump was stuck so new pump.
* After the first fuel blockage issue, I removed the fuel rail and cleaned the injectors and everything else. As a precaution I replaced the fuel rail regulator keeping the original. I replaced a high pressure pump to a standard 4-5 bar pump.
* After the second, same thing, cleaned everything in the lines but there was no dirt, the pressure issue started (also I noticed a slight bubbling sound coming from the fuel tank when I park up and sit in the car for a little, perhaps this is the start of that blockage. Again replaced the fuel rail regulator, just in case.
* After the third, another fuel rail regulator, clean filters as always (those metal ones, geez they expensive) and made sure everything was running fine.
By this time we have had 5 pumps / 3 fuel regulators on the rail / multiple fuel filters.

anyway, I'm looking for some advice on this because I am at my wits end with this now, I have been let down so many times with this fuel system it's driving me nuts. Much appreciated guys

[Ashveer03]

Been years since I've fiddled on a MK1, but if I remember correctly, the operating fuel pressure of MP9 is 3 bar.

If U remove the regulator from the rail, and use an air line on the return line, it should blow out whatever kak is blocking the system, if any. Basically send air pressure backwards. I haven't heard or seen of a blocked rail before. Lol

The other option, fit a polo 9n 3 bar fuel filter which has a built in regulator and U will only receive 3 bar at the rail. Probably have to cap off the return line on the rail if doing this instead of using a T.

[sophiawright]

@Ashveer03
Thank you so much for that, I was really starting to worry about this situation and ordered one of those adjustable fuel regulators to put on. I'll see how that goes so I can set the fuel rail pressure to 2.6 bar as per normal.
I'm such a numpty for not thinking about a fuel filter with a return. Thank you so much for the advice, I will see how much such a filter cost and then rather go that route if the regulator thing is a leak issue etc.
Also, I don't have a compressor to blow the gunk out, no idea why it would just be blocked completely. The original regulator valve had a few tiny specs of rust on it since it has that mesh on it, but nothing that would go through and get stuck, not even the O-ring came off so no idea what it is. My personal feeling about the rail is that this particular model of rails have some major issues ranging from fuel regulator valves / broken pipes inside / this is new "no return and blocked" to an aftermarket fuel regulator valves not lasting long and all this with a very dangerous situation as when I took the fuel filter of, it kind of exploded into my face due to the pressure.

On the subject of fuel filters etc., is there a cheaper filter one can get for the mp9, both the polo n9 and regular mp9 metal fuel filter is so expensive (no idea why they have to be so darn expensive - Yes I know those Toyota plastic fuel filters cannot handle the pressure and also the filter paper inside can break) but for heaven sake, it's stupid expensive for a alu metal can and some paper inside.

Another thing did you guys see how much a normal paper air filter costs these days; you can buy a K&N and 4 paper filters later you have reached the K&N price. I'm going to go down that route now and if I have to, dig a bit deeper to see if one can get a serviceable fuel filter

[Ashveer03]

Well unfortunately with inflation the price of everything rises. These are one of the cheapest metal filters in the market compared to other vehicles.

Fuel filters for injected cars were always much more than a carb filter.

Further more these filters have much longer life spans than the plastic carb filter, it's meant to be changed at inspection services only which is something stupid like 3yrs / 60k Kms or so.

I just change them at every 2nd service.

Good luck hope get it sorted out.