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fuel system design


pugwash
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I have to design my fuel system from scratch right up to the ruel rails.

This is what i have so far:

22gal Jaz foam filled tank

feeding 2 x Facet red tops (working as lift pumps)

feeding 1 2l swirl pot

feeding 1 EFI fuel pump (which must be gravity fed)

feeding 1 regulator (which is t'd for a fuel return (the fuel rails on an LS1 are returnless)

feeding the fuel rails

A few things that i can't decide or don't know.

where do i put the fuel filters? on the low pressure or high pressure side? Does it make any difference and what sort of fuel filter is best for off road- one of the galss globe jobbies that separates out water? the facets have filters in the bottom anyway- are these enough?

where should the return line run to- the tank or the swirl pot? i would guess if it goes to the swirl pot i "could" end up with quite hot fuel as it will just be circulating through the system getting hotter- is this likely?

Does the swirl pot fill from the top, bottom or mid point? i assume i need a return from the swirl pot to the fuel tank- or else what happens when the swirl pot fills up?

how high will the facet pumps lift the fuel- the higher the swirl pot the better for my application, but i don't want the facet pumps to be struggling.

any advice gratefully received.

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Fuel filter - I have used a competion filter made by sytec. Logically it wants to be before the EFI pump to protect it from bits although i put it straight after the EFI pump. I guess keeping bits out of the injectors is most important.

Why 2 red tops? They have something like 30 gallons per hour capacity so surely one is enough.

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I run a Facet as a lift pump and a Jag inline EFi pump. Both pumps have an appropriate filter after them and there's one on the return line from the fuel rail, half for filtration and half as a visual indication that the fuel system is working.

When I had the swirl pot fitted I ran the EFI return into the top of it and put a small inline filter on the return feed to the tank to restrict flow a bit and keep a little pressure in the swirl pot.

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Hello there,

I've just had enermous problems getting a 4.6efi running right with fuel problems etc and did a lot of asking around and research into it, so hopefully this might be of a little help.

If using a gravity fed pump regardless of wether or not it's fed from a swirl pot or direct of the tank the fuel filter should be on the pressurised side of the pump, that defies all logic of protecting he pump I know, the return to the tank may have to be of a larger bore pipe certainly not less and certainly not restrictive. I had massive problems getting a steady tickover when warm due to poor return, caused me loads of problems but when the engine is cold more fuel is used and when revving it obviously is, but when its warm and at tickover thats the time when most fuel is returned to tank and to stop to much pressure building in the fuel rail a good return is needed.

I bought a pump of RPI for about £90 its a Bosch blue pump which say they they use on motors with big outputs no problem at all, and since then whilst browsing through a auction website found exactly the same pump from another supplier for £22.50, did I feel gutted, yes I did. It was listed as Vectra, SDI Vitese, Rover etc, and fuels mine no problem, and at that price its worth trying and is an affordable spare.

On the question of swirl pots, its normally a race car that needs them for thrusting around corners to protect massive surges when the tank is near empty is the answer I got of the race boys, especilly on circuits with long constant turns, its the way I was heading but after some good advice on adjustable fuel pressure regulators and returns, I didn't go there and now run a big efi no problems at all.

Hope it helps, sorry if it doesn't and good luck.

Boothy out :)

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I have to design my fuel system from scratch right up to the ruel rails.

This is what i have so far:

22gal Jaz foam filled tank

feeding 2 x Facet red tops (working as lift pumps)

feeding 1 2l swirl pot

feeding 1 EFI fuel pump (which must be gravity fed)

feeding 1 regulator (which is t'd for a fuel return (the fuel rails on an LS1 are returnless)

feeding the fuel rails

A few things that i can't decide or don't know.

where do i put the fuel filters? on the low pressure or high pressure side? Does it make any difference and what sort of fuel filter is best for off road- one of the galss globe jobbies that separates out water? the facets have filters in the bottom anyway- are these enough?

where should the return line run to- the tank or the swirl pot? i would guess if it goes to the swirl pot i "could" end up with quite hot fuel as it will just be circulating through the system getting hotter- is this likely?

Does the swirl pot fill from the top, bottom or mid point? i assume i need a return from the swirl pot to the fuel tank- or else what happens when the swirl pot fills up?

how high will the facet pumps lift the fuel- the higher the swirl pot the better for my application, but i don't want the facet pumps to be struggling.

any advice gratefully received.

You certainly seem to have the start of a very nice system... don't balls it up now for the sake of a few more quid.

I did a very similar job on a TVR a while back and he has now had 3 complete seasons ( with some noteable success ) without having to touch the system since....

I would suggest 2 filters. 1 ( low pressure ) between the tank and the twin Facets. And one between the injection pump and the engine - this one will need to be a suitable one for injection ie. pressure and smaller partivles.

Feed into the swirl poy anywhaer ( middle? ) using lower for the feed to the injection pump and top for the return.

Don't spoil it all now by using crappy jubilee clips on the job with blackgarden hose that will harden in no time and crack. It will probably cost you a couple of hundred quid but use proper hose ( I sell -6 for about £23 a metre ) and threaded unions throughout. This is what will give you the reliability.

The facets will ( especially if they are as near as poss to the tank ) easily push the fuel up to the engine bay.

To save typing give me a call on 01938.850382 if you want to discuss any more thoughts on the system. And the 10% discount I offer to the forum members on brake hoses applies to all other fuel / oil hoses and fittings...

David

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Yeah its a tough decision. I did mine recently.

The proper 'Viton' hose is about 5 times the prices of 'regular' fuel hose, but it has a 15yr life as opposed to 5 year....

Your choice...

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