A question out of curiosity.

If i wanted to put an injection in my car instead of carbs, could i keep my fuel tank and fuel pump, but simply have the pump supplying a swirl pot from which the high pressure fuel pump could then pressurise the fuel rail.

It would be cheaper and i wouldn't have to pump in more fuel lines the whole length of my car for the returning fuel line.

What problems might there be with doing this?

[Edited on 12/8/07 by the dave]

In theory is might work, but my gut feeling is you would still need a return line to the fuel tank. The problem as I see it, is you will have your LP pump filling the swirl pot, and the return from the fuel rail filling the swirl pot.

This was the next question that I was going to ask. I have a swirl pot on it's way and wanted to avoid plumbing in an extra return line. I was going to use a breather valve on the top outlet of the swirl pot.

Simon

I used a swirl pot with a new fuel supply pipe to the injector rail but I have used the carb supply pipe as the return. Works fine for me

Can you clarify your setup please Rusty. Have you got two lines running to the fuel tank? How have you connected the top outlet/breather on the swirl pot?

Sorry if I am hijacking the thread, Dave.

Simon

no worries, it's all good stuff.

Hopefully a (very) rough sketch of what i had in mind.
Rescued attachment swirl.jpg

Thats more or less how I did mine. I put the swirl pot as high as I could get it so that H.P pump is gravity fed , Haven't had any problems with set up .

Thanks Dave and Rusty,

This is how I was thinking it would work.

I have only one connection on the fuel rail.

[Edited on 12/8/07 by Catatomic]
Rescued attachment fuellingSwirl.png

That is probably more accurate, i don't yet have any parts, just planning.

2 questions, what TB's do you have Cat, and what does MAP stand for?

MAP

Manifold Absolute Presure

Won't the LP pump just pi55 fuel out the breather?

[Edited on 12/8/07 by matt_claydon]

possibly, but when i started this thread i wasn't sure that the swirl pot needed a breather...

are we saying that this setup is not ideal?

surely the swirl pot will just keep filling up? eventually the fuel will come out of the breather? especially if, for instance, you were idling the engine in traffic... low fuel consumption means more returned to swirl pot so it begins to fill....

personally I wouldn't risk it! the idea of overflowing fuel into the engine bay is scary! I'm not sure I would want to vent fuel vapour into the engine bay either!

Find a fuel return pot from a Sierra and place it between your low pressure pump and swirl pot then run the regulator return on the end of your fuel rail to the swirl pot. The breather is just somewhere for the fuel to escape especially if there is no pressure cut off on the Low pressure pump. The MAP reads the depression in the manifold not fuel pressure doesn't it?

[Edited on 13/8/07 by Peteff]
Rescued attachment fuel system.jpeg

To the dave

The breather from the swirl pot must be a return to the fuel tank. Your low pressure pump is working full tilt and at idle will easily fill the swirl pot. I have exactly the set up you have drawn except for the open breather, mine is a tank return, and it works perfectly.


Cheers
JohnW

[Edited on 13/8/07 by ecsjwhi2]

neat single line solution there from peteff !

This is the swirl pot i was thinking of using.

If i connect it up as shown would it work. The reason for asking is it would be cheaper to get the swirl pot than a new tank with a swirl built in.

EDIT : I missed out the regulator

[Edited on 13/8/07 by the dave]
Rescued attachment 5.jpg

quote:

---

Originally posted by the dave
This is the swirl pot i was thinking of using.

If i connect it up as shown would it work. The reason for asking is it would be cheaper to get the swirl pot than a new tank with a swirl built in.

EDIT : I missed out the regulator

[Edited on 13/8/07 by the dave]

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I am using GSXR 600 throttle bodies. The reason I was trying to avoid a return line was to avoid clutter in the tunnel. I was going to put a non return valve on the breather and let the back pressure stop the LP pump (Facet)

Simon.

That is the same reason as me, as my car is already built plumbing in another fuel line would be tricky.

I can't see why that wouldnt work, unless there was too much fuel and it pressurized the swirl pot...but maybe not.

Might have to give that a try...not sure where to get the valve from though.

quote:

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Originally posted by Catatomic
I am using GSXR 600 throttle bodies. The reason I was trying to avoid a return line was to avoid clutter in the tunnel. I was going to put a non return valve on the breather and let the back pressure stop the LP pump (Facet)

Simon.

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to shamelessly steal PeteFF's rather neat solution......



Description

I can see no reason why this would not work perfectly well and allow for only one pipe running the length of the car.
The pressure regulator at the rear would allow excess fuel to be recircualted to the tank when the swirl pot was full therefore removing the need for an overflow.

It won't purge itself of air very well though, i.e. the low pressure pump isn't going to be able to pump fuel into the swirl pot whilst it's full of air as there will be nowhere for the air to go. Eventualy the injectors will purge the air out but could take a long time. Best to stick a manual bleed nipple in the top of the swirl pot if you have to go this route.

Need to add a high pressure pump at the swirl pot end on the diagram as well.

I thought of a bike type tank mounted pump built into the swirl pot to keep the space needed to a minimum, forgot to put it in the picture. Doh!

I looked at various ways of doing this when I first injected my car.I wanted to use the existing mechanical pump on the crossflow and feed the swirlpot with that but decided that I really needed to fit a return line to vent vapour to the tank and also didnt like the idea of a litre or so of extra fuel in the engine bay swirl pot in the event of an engine bay fire.The fuel would also get very hot in the swirl pot whilst driving in traffic as little would be used and the underbonnet temperature would be raised, this would probably effect the mixture control and also be likely to cause high pressure fuel pump problems.
I eventually fitted the pot in the back of the car and ran a nylon fuel return pipe secured with a few P clips.
Paul.

quote:

---

Originally posted by DaveFJ
to shamelessly steal PeteFF's rather neat solution......



Description

I can see no reason why this would not work perfectly well and allow for only one pipe running the length of the car.
The pressure regulator at the rear would allow excess fuel to be recircualted to the tank when the swirl pot was full therefore removing the need for an overflow.

---

Is there an optimum size of swirl pot.

If it was 1/2 ltr, i would have thought that it held more than enough fuel for hard cornering etc, is this right?

Also any recommendations for high pressure fuel pumps to work for the zetec, they seem to have lots of different stats and i'm not sure which ones are relevant.
Thanks

Ok here's another option, move the Low pressure pump tu the engine bay and feed the return of the swirlpot to a T piece before the low pressure pump in the engine bay.
that how mine used to work.. or get a golf pump that does it all for you!

There is a way that could work with only one line in the tunnel, but I don't know if it's been tested:

code:
 

                             -------------------------> To fuel rail 

                             | 

                             | 

    --------    -----------  |  ------------- 

 -->| Tank |--->| HP Pump |---->| Regulator |--------->--- 

 |  --------    -----------     -------------            | 

 |                                                       | 

 |                                                       | 

 -----------------------<---------------------------------