Fuel pumps and filters
 

Hi all, me again with more questions.

What approach do you recommend I take with fuel pumps and filters. There are loads on the market but I'm not sure what to go for. Are there makes worth spending extra on and any to avoid.

Bentley (160-10) specifes 43.5 PSI but I assume that would be for the high pressure pump to the fuel rail from the swirl pot rather than the one from the tank to swirl pot as in the donor there was only the single pump in the tank?

Bentley also on the same page states fuel pump delivery specifications of 0.87 l per 30 seconds so I make that ~105 litres per hour.

Is it safe to say that any non-injection pump that can meet that volume spec should do the job for the trip from the tank to the swirl pot? I then need to get an injection pump with at least the above pressure rating for the swirl pot to the rail?

What about filters? Obviously it/they need to allow the fuel through at the above rate. Do I need two or will just one after the tank pump do? I quite fancy one of those old school glass ones in the engine bay purely for asthetic reasons but again, not sure if appropriate.

The other thing is I've seen is fuel pump coolers but I'm not sure if they're a gimmick or a worthwhile option. obviously in the donor the pump was in the fuel so it would get cooled that way but in the sportster it's just going to be bolted on a bulkhead

I know this has been discussed here as I remember seeing some drawings from MarlinClan (I think) of his set up but I've not had any luck digging it out.

[EDIT] Oh, and are non-return valves required at any point?

Hi Ian,
I bought my fuel pumps from Marlin.
They provided a Facet 'Red Top' for the low pressure pump and a Sytec high pressure pump.
I didn't bother with a filter on the low pressure side as the pump has a built in gauze filter. (But I know others have fitted filters on both circuits) But you do need a filter on the high pressure side before the pump and injectors. I have a rather rare K&N filter that I think is discontinued but is designed for fuel injection systems and is dismantle'able to clean (which I had to do after my first big trip out!).
Sytec do some nice fancy filters but I'm not sure if the glass ones are suitable for fuel injection systems.

Robin's diagram can be found here...

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

I didn't use any non-return valves but you do need a proper fuel tank breather valve.

...peter

I am thinking to modify my tank and put a sump in it. I have seen this done somewhere but I cant find it right now. The idea is that the sump will add extra capacity and avoid the possibilty of fuel starvation under heavy braking/cornering therefore removing the need for a swirl pot and all the associated low pressure setup. It just requires a high pressure pump direct from the tank. I might fit two in parallel for additional reliability.
Has anyone any experience of doing this? - John

Not sure about on the Sportster, but Mike (http://www.flickr.com/photos/mikes_b...7617099808506/) and Simon (e.g. http://www.flickr.com/photos/marlin_...7603834123063/) have done it on the Cabrio (and I plan to do the same on mine). It would be even better if the pump could be accommodated in the tank as well.

Mark.

Mark! you are a genius! Thats the one - Mike again, I should have known it, he is full of good ideas. Thanks for saving me from hours of frustration! - John

Facet and sytec are some of the ones I was looking at. If possible I'd like to use threaded fittings with SS lines rather than push fit rubber and a clip though whether that will just over complicate things I'm not sure. adapting to the existing BMW rail and hard lines plus the out/inlets on swirl pots may just make it a bigger headache than it need be.

What ID should I go for on the high and low pressure side. does 10mm sound about right.

The other thing I thought may be cool, is a dash mounted fuel pressure gauge or warning light. not sure if you can buy them for anything other than testing though

Plenty of fuel pressure guages here:

http://www.caigauge.com/index.html

As for the warning light, you'd just need a pressure switch in the line like you do with your oil pressure - of course, you'd need to select one that has a sensible switching pressure. I'm sure CAI would be able to help if you gave them a ring.

Hi John

I have added a sump to my tank and hidden it behind the diff.

http://farm4.staticflickr.com/3514/3...a4412b29cf.jpg

http://farm5.staticflickr.com/4062/4...4c75ac7b4a.jpg


Simon Gregory has done it too.

http://farm1.staticflickr.com/112/27...bc799adcc8.jpg

Systec recommend this set up over a swirl pot, as it is more reliable (less to go wrong).

Mike

Hope you don't mind me gate crashing this thread - but it is relevant.


Having just wired up my Hi Pressure Sytec pump and brought it in to use, I am struck by how noisey it is - which is not a surprise as I was told it would be, but.....this loud?
What I did not expect was to hear the fuel rail making quiet a bit of noise too. You can hear the petrol rushing through it, even when the engine is on tickover (says a lot for how much the engine has now quietened down though from that awful rattly start!)

Can anyone else hear the fuel going through their fuel rail? I wonder if I have an air leak, with air being sucked in which might explain the fuel circulation noise? I think I have the fuel flowing the right way around the circuit - the pressure valve should come after the injectors, so as to raise the pressure feed to the injectors?

Peterux mentioned a valve in the return side - was this the pressure regulator at the end of the fuel rail, or should there be a fuel return flow valve just before the tank? I suspect my Systec is pushing far too much fuel around the system, but then again, there will be a big difference between the fuel requirement on tickover, and at full tilt at high speed?

What are others experiences?

Mike

I now want to hear an original M50 running to compare it.

Hi Mark

I looked at the possibility of using the BMW tank pump but it locates through a screw on cap. I could not figure out how to use the cap, and make a seal with a home made aluminium tank?

As an after the event comment, my pump is pretty loud, so having one in a tank would have been a better choice, if at all possible. In fact, if you have any idea for doing it, I would still consider having a go, and selling the Sytec pump on ebay.

Does anyone know of any other vehicle that has an in tank pump which would lend it self to fitting in a home made tank?

Mike

CBS sells this

http://www.cbsonline.co.uk/product/I...mp_45PSI_INJP3

Flow rate might not be enough for a single in tank pump application

I don't recall any particular noise from my Sytec or being able to hear fuel rushing through the fuel rail? Perhaps its sucking air from your petrol tank if you only have a small amount of fuel in it? I have heard that they don't like to run dry as the fuel keeps the pump motor cool!
I may have been sloppy with my words and yes its the pressure regulator at the end of the fuel rail. No other valves fitted or required.

But 'a noisy pump' rings a bell so I'll see if I can find what i'm thinking of...:noidea:
UPDATE:
This is what I was thinking of....
http://www.madabout-kitcars.com/foru...referrerid=181

not the same problem, though.

I used 10mm (or 3/8" copper?) as that is the diameter of the outlets on the tank and swirl pot. Dropping down to 8mm for the BMW rail connections.

Hi Mike,

I haven't got the fuel pump out of my donor yet so haven't been able to examine it at all. Re-using the BMW one would seem ideal though - as morris hints it might take some hunting around to find an aftermarket in-tank one of the same spec.

I think you said in another thread that you'd drilled a smallish number of holes in the original tank bottom to feed the sump? Would that mean you'd have to remove your sump so you could cut a much bigger hole in the original tank bottom for the pump pickup to fit through?

Mark.

I have a Sytec pump. It is mounted using the supplied rubber sleeve and bracket on the front bulkhead. Occaisionally I hear it (quietly) buzzing when priming the fuel system before the engine is started - but that's it. If yours is making a lot of noise then I would suggest something isn't quite right. As Peter mentioned - don't let it run dry. The fuel acts as a coolant and lubricant and it will quickly get knackered without it.

Robin

If that is true, then maybe the return fuel is not draining back into the sump quick enough and the pump is drawing in air.
Stick your ear to the tank filler hole and see what you can hear.
If it sounds like that sucker thing the dentist puts in your mouth you'll know what the issue is.:wink:

Noisely HI Pressure Pump
 

I put 5 litres of fuel in the tank, and there are 5 holes x 10mm diameter from the tank to the sump, and the sump holds 2 litres, so drawing air from within the tank is not the cause.
I considered it could be sucking air in at any of the joints prior to the pump, and this is still a possibility, but would have expected seapage of petrol out when left for a few days, yet have not spotted any (yet?)

Robin, I am interested that you have a Sytec pump but don't feel yours is loud? I guess all these things are relative, and personal, but I consider mine quite noisey. Do you have any restriction on thr return flow? I just feel the pump is pumping too much fuel around my system. I plan to talk to Sytec to see iof they can offer me any advice too.

......and I'll investigate all my joints more thoroughly.

Mike

Noiset Fuel Pump
 

I have spoken to Terry at Systec and he suggests it is possible there may be air being sucked in to the system, which would explain a noisey pump (due to cavitation) and a noisey fuel rail. He reckons any air in the system should be purghed withinn 15 - 20 seconds if it is air tight. I will have to check all my joints.

Ian's idea of screw fittings, rather than push ons, sounds quite good right now!

And I'm pleased I only went for a sump and one Hi Pressure pump, as it eliminates so many potential connection leaks with a swirl pot and second pump.

Mike

Just in the process of buying my fuel components and I noticed looking at Patrick's blog that he's put brass fittings into the marlin fuel tank 10mm inlet and outlet points (I assume just tapped). I had intended just whacking 10mm ID hose over the ends and clamping but now I'm wondering if without a decent flare on the end the hose will pop off. What have others done here?

I've bought my facet red top for the low pressure side but I'm having no luck finding a standard disposable filter sub £40 with 10mm fittings (all the £10 sytec ones are 8mm) so I may follow Peter's example and just rely on the built in filter in the pump at the back of the car. The alternative is to put in some 10-8 reducers in the lines either side but that means yet more joins and potential leaks. There isn't much room down there under the rear suspension anyway. I plan on saving the expensive filter for the front on the high pressure post swirl pot side.

The other question I had relates to the types of hose clips required. I see a lot of adverts for fuel line clips of the type with a screw running across the top rather than a plain jubilee clip. Are these better suited to fuel applications due to the size of the pipe or just down to personal preference?

Ian

I was advised by a one man band pipe supplier for 25 years, that the screw across the top is the better clip. Apparently they create a more uniform pressure around the entire diameter! So that's what I used for my fuel lines.

One mistake I felt I made was to use the stainless braided pipes with the pretty end covers - look really nice, but a PITA to make a good seal. Stick with bog standard proper fuel hose R9 grade.

Mike