ZetecVan
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| posted on 6/7/06 at 04:17 PM |
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Howling Fuel Pressure Regulator
I fitted a new fuel pump yesterday, and my fuel pressure regulator started screeching like a banshee. The pressure is set to 3 bar and it seems to be
working ok. The regulator is only 300 miles old. Has anyone had any experience of this?
Also, is there a calculation for flow rate vs pressure? eg: my injectors flow at 400cc/min at 3 bar. So at 1 bar is it 400 / 3 or is there a more
complicated formula?
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MikeRJ
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| posted on 6/7/06 at 04:26 PM |
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Air in the fuel system makes regulators noisy, as does having anything "compressible" on the pressure side of the fuel rail, e.g. non-high
pressure fuel hose that can swell up.
The flow vs pressure relationship is is a square law i.e. doubling pressure only gives you SQR(2)=1.41 times as much flow. So to calculate flow:
New Flow = SQR(New Pressure/Old Pressure) * Old Flow
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ZetecVan
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| posted on 6/7/06 at 04:53 PM |
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Thanks for the quick reply. I don't think there's air in the system, but its a possibility. Between the pump and the regulator I have
flexible injection hose. Could that be the cause? Should I have used copper piping?
[Edited on 6/7/06 by ZetecVan]
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stevebubs
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| posted on 6/7/06 at 05:19 PM |
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Proper flexible injection pipe is fine
I'm sure it is, but your regulator is *after* the injectors, isn't it
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ZetecVan
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| posted on 6/7/06 at 05:52 PM |
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quote:
Originally posted by stevebubs
Proper flexible injection pipe is fine
I'm sure it is, but your regulator is *after* the injectors, isn't it
Yeah it is 
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mr zefect
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| posted on 7/7/06 at 10:28 PM |
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Does it screech when the vacume is disconected. ps are 300cc injectors not to big running on a 18L zetec mine are only 175cc 18L 130ps zetec ones on a
20L and goes very well. Or are mine to small.
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ZetecVan
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| posted on 8/7/06 at 08:07 PM |
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I don't think they are too big, as they're obviously not open all the time. The duty cycle gauge on the megasquirt is nice and low, which
is nice...
Yes, it does screech with the vacuum off, because after it dit it the first time I noticed it was off, so put it back on, and it still did it. On the
odd occasion I turned the ignition off then back on again, and it stopped doing it.
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stevebubs
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| posted on 15/7/06 at 12:21 AM |
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quote:
Originally posted by mr zefect
Does it screech when the vacume is disconected. ps are 300cc injectors not to big running on a 18L zetec mine are only 175cc 18L 130ps zetec ones on a
20L and goes very well. Or are mine to small.
300cc is probably a bit big but the only side effect may be a slight lack of granularity with the fuelling at idle...not a huge problem, though.
I've got purple injectors off a Vectra GSi on mine and they seem pretty much spot on. Don't know the flow rate, though
[Edited on 15/7/06 by stevebubs]
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