Engine problems - dirty fuel

[Sp!ke]

Surely once you've removed the dirty fuel you could simply filter it (thinking paper coffee filter or similar) and put it back in the tank afterwards. This would be a lot easier than finding a way to dispose of it no?

 

[Charles Morgan]

Indeed Spike - I'll get it all filtered and use it in the lawnmower etc. The 30 litres I took out (the limit allowed for home storage) was pretty clean, but then it had been standing for nigh on a month without moving and was from the top of the tank.

I'm inclined to think given the pumps both sit before the filter and the distance I covered before the car starting playing up (a mile) the new filter should not have clogged in that time.

 

[Technocrat]

using a high detergent fuel like BP ultimate has helped cars in the past. A few tank fulls works well.

 

[Charles Morgan]

Car is now officially a Dodo, battery was flat yesterday so charged it, it started but kept on conking out and is now not starting at all. The buzz of the fuel pump is missing, so I think that is part of the problem. Off to specialist time.

 

[Charles Morgan]

Update time, with space on the drive and no wet, I decided to get into some problem solving. Removed the fuel pump and the fuel filter, the latter new, the former also pretty new looking. Fuel pump was blown through with compressed air as was filter. A standalone test of the fuel pump showed it working perfectly and when re-connected to the fuel tank it happily poured fuel through.

So any major problems are forward of the pump and fuel filter. Having fitted a new battery I had no joy in starting. Next thing is to check all the fuses and then see if the fuel lines need clearing.

In getting underneath (after having to clear a semi-eaten mouse within a pile of cat poo, thanks) I did however find this hole in the exhaust centre box (there's a front box, this and then another behind). Oh joy!

 

[grober]

FOUND THIS IN THE REAL OEM ARCHIVE SECTION.

TANK DIAGRAM
RealOEM.com * BMW E28 M535i FUEL TANK/FUEL FEED
FUEL FEED
RealOEM.com * Diagram Selection

Looking back at that fuel rail diagram in post #12 under fuel cooling 3rd diagram down that item no 1 64531386484 Looks to be some form of heat exchanger??? might be worth a look for internal leakage /blockage - you could short it out temporarily to test??

 

[Charles Morgan]

Good spot Mr G!

I need to get new bonnet supports as the old ones have gone, blinking pain. Plenty of chocks in the meantime.

 

[Bellow]

Looking back at that fuel rail diagram in post #12 under fuel cooling 3rd diagram down that item no 1 64531386484 Looks to be some form of heat exchanger??? might be worth a look for internal leakage /blockage - you could short it out temporarily to test??

Fuel cooling is usually applied to fuel that has been pressurised (hence heat) and is being returned to tank as overspill from pressure regulator. Any blockage in return lines will increase not decrease delivery pressure.

 

[Charles Morgan]

Having checked what I can, there was some evidence of dirty fuel. Messing around with pressurised fuel lines and rails is not something I should be doing, so I'll have it recovered to a local BMW specialist after the holidays and get it off the drive.

 

[Charles Morgan]

Having tired of it on the driveway it was taken up to Simeon last Friday and I popped in today. The diagnosis was a dodgy earth for the fuel pump relay and once sorted the car fired into life, which is nice. So while dirty fuel was involved it was a simple electrical issue. The poor run home from the garage we decided was that the in-tank pump was still functioning but without the main pump was insufficient to keep the fuel supply going and it was failing too.

The centre box will be welded and I will soon have one fewer non-runner on the drive. Hooray!