Ok fellow hydrocarbon heads quick challenge, I think i know the answer just want some confirmation before spending hard earned cash

Got a ford Twincam with EFI in my vindicator Family and under normal driving have no problems, however under hard driving particularly when cornering or when fuel level is lowish the engine splutters and misses then picks up again.

Got a large tank across the back of the car with what the manufacturer called a swirl pot, which is about 3-4" cube mounted below the main tank. The fuel return goes into this and I have a high pressure fuel pump between swirl pot and engine but the feed from main tank to swirl pot is gravity fed.

I suspect the engine is suffering from fuel starvation and i need a low pressure pump to fit between main tank and swirl pot.

I know its difficult to diagnose without experiencing it but in your combined esteemed opinions is this likely the case. Is a low pressure fuel pump likely to cure it. And finally do the low pressure fuel pumps run contiuosly or do they have an internal pressure switch such that if the swirl pot is full they wont continue to try and pump fuel into it.

Also posted on rhocar so if you have answered there no need to answer twice

see below


Image deleted by owner

Both pumps just circulate the fuel around their respective circuits

[Edited on 23/4/10 by big-vee-twin]

Thanks for that however there is a slight problem.

Only got 3 connections to the swirl pot and that drawing says I need 4

Havent got a spaer connection for the overflow return

[Edited on 23/4/10 by Vindi_andy]

Thats probabily why you havent got a low pressure pump - it does sound like starvation to me though, but the pic is pretty much how most people do it.

thanks for that.

Just one thing to say. BU66ER I didnt make the swirl pot and i dont fancy welding a new threaded fitting in it now

As a thought, could you not run your return from the fuel rail straight back to the main tank, and then use the 3 connections on the swirl for Low Pressure Input, High Pressure Output, and Overflow?

Could you put a "T" into the swirl pot to tank return and then put the fuel return into the "T" too?

Bob

thanks guys knew I could rely on you

quote:

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Originally posted by PSpirine
As a thought, could you not run your return from the fuel rail straight back to the main tank, and then use the 3 connections on the swirl for Low Pressure Input, High Pressure Output, and Overflow?

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Ah, didn't realise your main tank was also lacking one connection!

In that case, yep you'll probably need a T-piece (don't use the breather as you'll just create an airlock). I'd be tempted to stick the T piece so that it's between the main tank and swirl overflow, with the main fuel rail return tapping into the T.

The only thing you might get is backflow into the swirlpot from the rail return... which isn't ideal as all your fuel pressures will be all over the place depending on fuel usage.

Does your main tank only have 2 connections + breather?

yes main tank only has 2 connections and breather. the more answers I get on this the more it seems the manufacturer who supplied me the tank and swirl pot (at the same time under their recomendation) has dropped a cod

I have already fitted a non-return valve in the fuel rail return, because i didnt want the tank emptying via the fuel return, so if I fit the T piece between the main tank and the non return it shouldnt affect the pressures

i think it makes more sense for the fuel return to go to main tank where it can lose heat, rather than go back into the swirl pot and straight back to engine, i know i would do that myself

then just T into the return from the swirl pot onto the main tank

jobs jobbed

ps also i think the pressure reg should be before fuel rail on the drawing them injectors will be getting whatever pressure pump is running, i would also have the pre filter before inlet into LP pump

[Edited on 23/4/10 by dlatch]

The way you suggested with the T between the valve and main tank is a good way of doing it I think.

Ideally, I'd try and weld a connector onto either the swirl pot or your main tank to be honest.

(Personally if it was my car, I'd probably chemical metal a nipple on top of the main tank, use that for the little breather hose, and then connect the swirl pot overflow to the current, properly welded breather connection!)

there is a threaded fitting welded to the top of the tank for the breather with is a metal hose fitting and a length of fuel hose. If I do as you suggest PS and chem metal a breather onto the top of the tank then I could use that fitting to connect the swirl overflow to.

Post stoneleigh mods methinks. want to use Tango while the sun is shining.