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But thats got me thinking - does it need 12mm pipes? The stock E30 system uses 8mm through out including the pump and fuel filter (its a giant over size one)
Hi Patrick,
The fuel filter at the top of your page is for carb systems which only run at low pressure. If you are using an external fuel pump then you require 2 filters, one on the inlet port and one on the pressure side. The inlet filter protects the pump and the pressure filter the injectors etc. I found it difficult finding an inlet filter as most vehicles have them built into the pickup pipe in the tank, I stumbled on an ideal filter on an old AUDI 80 or 100 which had a 90 degree bend and pipe size of about 12mm and was only about £5.
The choice for pressure filter is easier, just take a look through a filter catalogue and pick the one that suits your application. I have piped my latest kit in hard nylon pipes so used a filter to match with push fittings.
thanks for the info, this is getting more confusing! I wish I had a build manual with this sort of info in it!
Do you have any links or part numbers for the audi filter? Can you suggest a good place to get a high pressure filter? The only place I've found that lists them so far is burton power.
Thanks, Patrick
EDIT I've had a bit of a look on eBay there a few BMW specific high pressure filter on there so I'll probs get one of those.
EDIT2: I've had a bit of a look on http://www.gsfcarparts.com/ - is that audi filter on there? I've had a quick look but cant see anything that seems to fit.
I am also confused. Why use two filters? If you filter the fuel before the pump why do you then need to filter it again after? I don't see how the pump itself can introduce any muck into the fuel - unless you have to allow for particles of the pump vane wearing off - but surely these will be absoluletly miniscule.
I had a look at the donor in tank pump and that has a fine mesh at the bottom of it to stop big particles - thats the only pre pump filtration I could see.
Hi guys,
I will try and get the part number for you, it might require me getting under the Sportster which is not at home at the moment.
The reason for two filters is the prefilter just protects the pump from large dirt particles which could seize rotor, smaller particles are still allowed through which would damage the injectors etc so that's why a main filter is required, in fact there is even tiny filters in every injector.
I got myself an Audi 100 fuel filter, but its got M14 threads on it (one side M12 in the filter with m12 to m14 adapter), and I cant find any 12mm fuel pipe unions for it I've managed to find M10 unions with 12mm pipe connections though.
I can probably make adapters for the M12 end, but ive not got an m14 tap.
I contacted FSE (01784 493555) ([url]www.fuelsystem.co.uk[/url]) they supply nothing but fuel related components - in fact I suspect this is where Marlin get their pumps from. I asked for some technical advice and they were very helpful.
In the end I have decided to use their (FSE's) fuel swirl pot. It has a built in filter and looks like a properly engineered bit of kit. All I will need is a very fine post high pressure pump - pre injectors filter for which I intend to use the standard BMW one (about £5)
The guy at FSE told me that I didn't need a filter to protect the low pressure pump as it already has a gauze filter built in that is adequate. (This wasn't just bull as he asked me what type of low pressure pump I was using just to be sure)
So my final system will be:
Fuel tank
Red top low pressure pump (from Marlin)
FSE swirl pot
High pressure pump (from Marlin)
BMW filter
Injectors
Anyone want to buy my Marlin made swirl pot - going cheap hwell:
OK, so we will have three different 'testbeds' to compare!
I am using Facet Redtop low pressue pump,
Marlin Swirl pot (mounted upside down, becuase it fitted better that way!),
K&N high pressure filter
and an FSE high pressure pump.
One things for sure, I won't be short of fuel pressure!
Thanks for the tip about the fuel sender sealing ring. I never did get to that this weekend as I got distracted fitting my coil, engine loom (again) and battery clamps.
Started de-rusting the old BMW horns. Not sure they are worth the effort but they still work great, so thought I would try to save them. One of the few non-BMW or Bosch parts. They are made by Fiamm, Italy. So I guess the Germans don't do horns??
Small follow up on the fuel sender, just the blue stuff didnt seem to do it - probably didnt use enough. So now I've used the blue stuff with the rubber gasket which has done the job
I've managed to find M10 unions with 12mm pipe connections though. 
all the bits and pieces are starting to add up. 
hwell: