electric fuel pump pressure?

Road-race engines and ancillaries - general discussion
bernie
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electric fuel pump pressure?

Post by bernie » May 14th, 2012, 5:09 pm

Fairly simple request but I cannot find the answer in my book collection.

I would like to replace the original electric fuel pump in my 1976 Fiat 124 Spider 1800cc CS1.
Engine, carb and tune are standard spec.
1.What is the standard spec pressure of the pump?
2.Anyone recommend a pump to fit and is a regulator necessary?

Thanks
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Urbancamo
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Re: electric fuel pump pressure?

Post by Urbancamo » May 14th, 2012, 7:06 pm

Basically all Weber and Dellorto carbs like to have fuel pressure in 0.2 bar region. Definately not much more.
You want enought flow but no high pressure. Regulator is not necessary if fuel pressure isn't too high.

I personally like German engineered and manufactured Huco pumps, they are quiet and very reliable. But every one might have their own opinion here.

T
GC_25

nabihelosta
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Re: electric fuel pump pressure?

Post by nabihelosta » May 14th, 2012, 9:17 pm

If it has twin Webers, I'd go with a Facet Silver Top fuel pump, trunk mounted (as it is a pusher).

Monitor your fuel pressure with a gauge. Try to stay between 3 and 4 PSI (0.2-0.3 BAR) pump on, engine off. If it isn't possible for any reason, you can always use a Filter King regulator, or borrow some Alfa Romeo Giulietta regulator (built-in fuel filter).

Thank you.

(P.S: I have seen some cars lately, using japanese made fuel pumps, same interruptor type as the Facet, originary equipping carbed Hondas or Mitsubishis from mid nineties. Is that even an option/alternative?? Thank you).

Nabih
HORSEPOWERunlimited

Guy Croft
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Re: electric fuel pump pressure?

Post by Guy Croft » May 15th, 2012, 12:26 pm

90% of my reason for using Facet is I can get them very easily thru reliable friends Northampton Motorsport*

I only started using Malpassi Filter King units quite recently, no matter that I rebuilt IDF carbs with great care - much more than 4psi line pressure (engine off - measured at the carb) they showed an alarming tendency to flood and fill up the barrel with gasoline.


G

* shameless 'plug' there...

bernie
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Re: electric fuel pump pressure?

Post by bernie » May 16th, 2012, 6:41 pm

Thanks to all for their response.

I see Facet pumps come in various pressures namely
1.5 to 2.5 psi SS500
2.5 to 3.5 psi SS501
4.0 to 5.5 psi

Care to say which I need?
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turbofiat
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Re: electric fuel pump pressure?

Post by turbofiat » May 17th, 2012, 4:39 pm

Is there anyway to properly measure the pressure with a diaphram type pump? The only time I've ever managed to measure fuel pressure properly is with a rotary vain type (Bosch L-jet).

With mechanical or electric style with uses a diaphram, the pressure guage flickers like mad and it's hard to get a good reading.

I don't know it this is a due to the guage itself or this would happen with all pumps. I tried a couple of difference fuel pressure guages on my Yugo but they were not all that expensive (<$20), Mr. Gasket was one of those brands.

I originally had a cheap boost guage on my Yugo that would do this at idle (vacuum mode). I replaced it with a VDO and the needle doesn't flicker. So the VDO guage may have some sort of damper in it where cheaper guages do not.
124 Spider, Yugo,131

Brit01
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Re: electric fuel pump pressure?

Post by Brit01 » May 17th, 2012, 4:48 pm

turbofiat,

If you have fluctuations you can use a small damping advice as I do with a vacuum meter when measuring the carbs. I use a small aquarium air pump tap that I can use to smooth out the fluctuations.

I'm sure this would work with the fuel also. (as long as it doesn't leak). Test it with water first.

bernie
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Re: electric fuel pump pressure?

Post by bernie » May 17th, 2012, 4:57 pm

I suppose the SS500 is probably suitable?
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Guy Croft
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Re: electric fuel pump pressure?

Post by Guy Croft » May 18th, 2012, 9:37 am

Yes, that's the one. Here is the link to the UK importer, FSE.

http://www.fuelsystem.co.uk

Among other things there is a very good page on the Facet fuel pumps giving part nos and data. I have the pump page printed off and refer to it frequently.

G

bernie
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Re: electric fuel pump pressure?

Post by bernie » May 18th, 2012, 10:41 am

Thanks Guy
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Brit01
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Re: electric fuel pump pressure?

Post by Brit01 » May 18th, 2012, 1:11 pm

What's the difference between the cube and posi-flow facet pumps?

Chris

Guy Croft
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Re: electric fuel pump pressure?

Post by Guy Croft » May 18th, 2012, 2:26 pm

Dunno really Chris, always just favoured the more expensive cylindrical ones.

From memory I think the little square ones are a bit noisy.

G

Brit01
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Re: electric fuel pump pressure?

Post by Brit01 » May 18th, 2012, 7:30 pm

Thanks Guy.

And they look nicer! Well no need for a Facet right now in my case. My mechanic has got the new QH pump going so lets see how it behaves after a week of sitting around. The diaphragm was much thicker than the old one (I suspect they changed the old one here in Uruguay one time due to the messed up cross head screws!!). New one is Italian made and sold by a British company, QH. Nice 3mm allen bolts holding down the diaphragm instead of screws.

Chris

Guy Croft
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Re: electric fuel pump pressure?

Post by Guy Croft » May 19th, 2012, 12:26 pm

I have never found QA to be anything but good..

G

bernie
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Re: electric fuel pump pressure?

Post by bernie » May 19th, 2012, 7:56 pm

Guy Croft wrote:I have never found QA to be anything but good..

G
Freudian slip Guy?
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