Help with fuel tank flow plans and brake pipes please!

Bobnic · #1 15th October 2011, 13:33

Hi, At the stage now where the fuel tank and fuel lines can now go on/in the chassis. Was wondering if any of you might have a plan of the fuel tank flow please, i.e feed/return etc.. and also a plan of the fuel line circuit please and any tips on installation. Next stage after that is putting the engine in

!! Then the wiring begins

Thanks

Rob

MartinClan · #2 15th October 2011, 18:54

Most people have used a low pressure pump at the back adjacent to the tank. This feeds a swirl pot up on the front bulkhead somewhere. I used an aftermarket one - others used the Marlin one. Output from the swirlpot feeds the high pressure pump. Overflow from the swirlpot back to the tank.

Return from the pressure regulator in the fuel injection also needs to be dealt with. I teed mine in to the return from the swirl pot. If you are using the Marlin swirl pot it has an additional input for the return from the regulator.

Don't forget at least one fuel filter. My low pressure pump had an integrated coarse one but you also need a super fine one before the hight pressure pump. I used an OEM BMW one.

Make sure you have proof that your fuel lines are designated as such.The SVA people nearly always ask for documentary evidence on this point.

If you have any more specific questions please ask...

Cheers

Robin

peterux · #3 15th October 2011, 22:02

And Robin has probably forgotten that he has a very useful diagram on his own website.

http://myweb.tiscali.co.uk/martincla...ystem_diag.jpg

As Robin says, if you are using the Marlin swirl pot then the return line 'F' in his diagram goes back to the fourth connection.

I used the Marlin swirl tank and used the top two connections for the low pressure pump and bottom two for the high pressure feed and return.
There is a another thread below called 'Marlin Swirl Pot' that has a similar discussion.

Fuel lines and brake pipes should be adequately fixed with 'p' clips or similar, in accordance with that specified in the IVA regulations.

MartinClan · #4 16th October 2011, 17:43

Quote:

Originally Posted by peterux

And Robin has probably forgotten that he has a very useful diagram on his own website.

Indeed I had!. In fact diagram is slightly wrong as J and B are in copper - not flexi as the diagram implies.

Robin

Bobnic · #5 16th October 2011, 18:24

Thanks Peter and Robin. Top Job Robin, you should be rightly proud of your diagram!!

Regards

Rob

Patrick · #6 17th October 2011, 20:01

I have tank -> filter -> hi pressure pump -> filter -> fuel rail -> return to tank.

I have a sump in the tank rather than a swirlpot setup.

As for pipe running this pics shows what I've down:

Bobnic · #7 18th October 2011, 23:37

Thanks Patrick. A few things on the whole fuel pipe/flow thing.
1. Do the filters go AFTER the pumps?? My head says before, but you guys seem to have gone for after each pump.
2. Can I get away with 8mm pipe all the way through with adaptors, or do i need different bores to aid fulel flow??
3. On yours (and others) you have a mix of copper and flexi, can I get away with all flexi, or am I missing something basic (along with all the rest of this flaming build!!!)??? Lol.
Still loving it though, but do remember yours and others wise words about, not enough time/space/money/spouse patience etc... but all coming home to roost at once is pretty messy stuff!!

Bobnic · #8 18th October 2011, 23:39

And another thing (sorry!) Did you tap the spigots on the Marlin fuel tank to accept the brass junctions? Too late, too tired, almost went to bed via the garage..urge to build, rising!

GreatOldOne · #9 19th October 2011, 07:22

All my filters are pre-pump. There's a filter built into my low pressure pump at the back, and then the fuel is routed to the swirl pot -> Fuel Filter -> High Pressure Pump -> Fuel Rail -> Pressure Reg -> Swirl Pot -> Tank Return.

http://www.greatoldone.co.uk/Gooster...d_Again_2.html

Bobnic · #10 19th October 2011, 11:30

Thanks GOO, all diagrams/advice greatfully received. Parts needed on way from CBS and T'bay, should have done by end of weekend........Uh oh sounds like a deadline to me, not a smart move!

Mike · #11 19th October 2011, 14:36

Rob

When I spoke to Sytec about fuel systems they advised keeping the fuel pump below the level of the fuel tank to ensure it will always remain primed. They advised that they burn our very quickly if they are allowed to run dry, even if for only a few seconds.
Mike

MartinClan · #12 19th October 2011, 19:17

Quote:

Originally Posted by Mike

Rob

When I spoke to Sytec about fuel systems they advised keeping the fuel pump below the level of the fuel tank to ensure it will always remain primed. They advised that they burn our very quickly if they are allowed to run dry, even if for only a few seconds.
Mike

I bought my swirl pot from Sytec and they seem to know their onions (and fuel systems). The problem with the HP pump is that they actually use the fuel for cooling (scary huh) and so if they run dry the motor rapidly overheats as well as doing the pump itself not a lot of good.

Robin

Patrick · #13 19th October 2011, 20:03

In the stock fuel system there is a mesh over the pick up pipe, no so in the Sportster tank which is why in my setup I have filter both before and after the pump. I'm using 10mm pipe to the first filter and then 8mm down past the diff. After that I switch to copper which runs up the centre tunnel. At the front of the car I switch back the pipe up to the fuel rail.

There's no reason you couldn't use flexi pipe all the way, however the rubber is more likely to go old a crack before the copper needs replacing so purely from a servicing point of view it's more convenient in the long term.

Bobnic · #14 19th October 2011, 20:26

Thanks Patrick, Another question. Did you tap the spigots on the Marlin fuel tank to accept the brass junctions as seen in your photos then attached the flexi to that? Just feel the walls of the spigots are quite thin, don't wanna split them!! If you did tap them any tips please??

peterux · #15 19th October 2011, 20:38

Quote:

Originally Posted by Mike

Rob

When I spoke to Sytec about fuel systems they advised keeping the fuel pump below the level of the fuel tank to ensure it will always remain primed. They advised that they burn our very quickly if they are allowed to run dry, even if for only a few seconds.
Mike

That's interesting, I don't think I knew that when I mounted mine low down on the nearside chassis rail. It was just the most convenient place to mount it between the filter and the fuel rail.

Fuel pump by marlinpeter, on Flickr

Unlike factory built cars with the pump mounted on top of the pedal box which is both above the tank and the 'swirl' pot?

Marlin's Sportster by marlinpeter, on Flickr

I used a rather unusual 'K&N' fuel filter that you can take apart to clean out.

Making good progress by marlinpeter, on Flickr

Patrick · #16 19th October 2011, 21:21

I tapped the tank to fit the brass union. Ali is soft so you need to use cutting compound/oil and go slow. No more than 1/4 of a turn at a time. Remove the tap often and clean then you should be fine

I used some brake and air pipe sealant when put the unions in.

Bobnic · #17 19th October 2011, 21:30

Thanks Patrick, much appreciated!! Shall steal your idea, if you don't mind.

peterux · #18 21st October 2011, 08:39

Quote:

Originally Posted by peterux

Fuel lines and brake pipes should be adequately fixed with 'p' clips or similar, in accordance with that specified in the IVA regulations.

I have just read that there is now doubt over whether copper fuel lines meet the IVA requirements. Nigel Dean, from Kit car magazine has tried to get clarification from VOSA who (unhelpfully?) just repeated the requirements that the pipes need to be marked confirming their suitability. The problem is that copper pipe is BS kitemarked but the BS standard is for domestic central heating systems and doesn't cover petrol based fluids.
Nigel's recommendation is to use rubber fuel hose all the way from tank to swirl pot with the correct markings.
You may get away with copper like I and other builders have used (I had no problem or question at my SVA) but using correctly marked pipe removes any doubt or discussion.
This is just one example...
http://www.fuelsystem.co.uk/Fuel%20P...ccessories.pdf

I hope this is not too late?

Chris Cussen · #19 21st October 2011, 09:41

My IVA tester did not query the copper pipe I used for the long runs to/from fuel tank to front of the car. But then maybe he hadn't read all of the IVA manual, or thought they were suitable.

Bobnic · #20 26th October 2011, 22:05

Patrick, What size hose and thread combo did you use when you tapped your fuel tank with the brass connectors please. Don't want to order a load of the wrong size!!

Thanks in advance.

Rob