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Fuel pump etc questions


Josh

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well if you don't want it just don't run one. I didn't.. and still don't.. and probably never will. I may open up my drop tank and get better baffles in though..

you will still return to your tank.. and you will use the outlet you made.

It will go like this:

outlet of tank to non pressure filter, electric pump to the surge tank then to your bosh efi pump, then under your car, up to the enginebay, a EFi fuel filter, fuel rail, pressure reg, back to the top of your tank. :P

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I dont want to run run, fuck if I keep it above 1/3-1/2 tank it'll be sweet, till I can maybe do a surge tank setup later down the track.

The fact you ran it like this RT anyway seems to make up my mind.

How much are these electric fuel pumps to feed the surge tankj?

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$50 from the wreckers, you can use about anything, a VL commie one would be good. All it has to do is keep a little tank fill.

yeah I dunno.. the only reason I didn't run one is because with a drop-tank setup you aren't allowed to bring the fuel inside the cabin, unlike your car where you can put it in the boot behind the tank. The other reason was cost and I was trying to save money.

it did get annoying..

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if you've been welding shit to the tank. you may as well cut the bottom out of it around the pick up. weld some baffles onto the bit you cut out, then weld it back in. done this to the kp, has never surged. even when the tank is near empty

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I've never seen it done. I would imagine you'd get all sorts of troubles if you were trying to fill it and pressurise it.

Its always just: tank > high volume pump > surge tank > high pressure pump > (damper and filters) > fuel rail > fpr > (now low pressure) surge tank > overflow back to tank

Thats how I'd set it up anyway.

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ahh I see. Cheers.

And have you ever seen a set up with only one pump but stil running a surge tank? Like one big pump after the surge so that it fills the tank and then sucks from the tank? Ive been told this is also a way to do it.

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Theres no real point to that setup that I can see. Apparantly high pressure pumps don't suck well (useless bitches) so you need to be feeding it lots of fuel, hence the reason for a surge tank. To have the pump so it needs to some how fill the surge tank first and then supply a constant high pressure flow to the fuel rail would be difficult or impossible, unless the surge tank had a way of maintaining its level without the help of the pump.

Thats how I see it anyway. I even drew a little picture to help make my brain work.

Just use a shitty old high volume carb pump to fill the surge tank. No reason not to and they aren't expensive.

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My ute runs a small sump off the bottom of the tank with the high pressure pump (from TA63 Carina turbo) sucking from that.

Thats a really good idea aye. Its pretty much what I meant when I said a surge tank that maintains its level. Is it common to have a fuel pickup like that?

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If you look at aftermarket fuel cells, they normally always have a little section that drops lower than the rest of the tank where the outlet is, the idea being that the little recess is a sort of surge tank cos it always has fuel innit. You can accomplish the same results by being clever with baffles and keeping the fuel where you want it. Modern EFI cars normally have pretty well designed tanks with a lot of baffles, however older carbed cars tend not to. As far as saying 'keep it above half full all the time and you'll be fine' it may work for some cars in some situations and not for others in the same situation due to tank design. Our evo 5 rallycar suffers from massive surge at anything less than about 3/4 tank, but only around right hand corners on tarmac, left hand corners are no issue whatsoever. The old VR4 never had this problem, it only ever surged when fuel was below about 1/3 full.

There is no quick answer, my big concern with running no surge tank would be running out of go juice mid corner, specially if if the car is a moderately powerful RWD chassis of older design, could get mighty hairy....

is it feasable to flip the tank upside down and put it in the boot or spare wheel well? then you could have a small drop type tank coming out of the original tank feeding straight into you efi pump. Other wise geminis have a pretty adaptable looking tank, it sits behind the back seat between the strut towers and is a fairly uniform shape.

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Capri has the tank behind the rear seats/between the rear struts to.

Have sussed out how I'd run the surge tank setup now, however been thinking about baffles now, or getting a bit welded into the bottom of the tank that would act like a surge tank as suggested above.

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