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Impreza Fuel pressure

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Tue Mar 06, 2018 7:47 am PostPost subject: Impreza Fuel pressure
Wull
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What should the fuel pressure be @ idle?

Car has 850cc injectors, afpr and as far as I'm aware....std fuel pump.

I'm not sure whether it should be different to a std car or not or what it should be, car was running perfect afr before making 11-12 on full chat but it's now doing 13's and I'm trying to suss out why the sudden change in afr as nothing has been touched.

O2 sensor was changed before the last mapping session but during that session the afr's were bang on, was consistently in the 11's to the redline.

Any ideas?



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Tue Mar 06, 2018 8:25 am PostPost subject:
AK
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Can a standard pump do much more than that power?!

Base fuel pressure is normally 3bar
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Tue Mar 06, 2018 8:35 am PostPost subject:
Wull
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AK wrote:
Can a standard pump do much more than that power?!

Base fuel pressure is normally 3bar


That makes sense, my boost gauge shows -0.8 bar ish @ idle and my fuel pressure is @ 2.2 bar at this point.

Everyone is saying 3 bar set with vac line removed.

Iíll check it at some point today but it looks likely that the fpr is fine and the issue could be elsewhere, but I wonder if under load what is happening with the fuel pressure. It goes up when I touch the throttle body but I canít simulate full chat or full boost.
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Wed Mar 07, 2018 7:03 am PostPost subject:
Vroomtshh
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If its the original fuel pump, theres a good chance it can't cope at full boost. It'll need to pump another couple of bar at that point and might just not be up to it. Ideally needs fuel pressure checking to see that it follows boost
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Wed Mar 07, 2018 8:47 pm PostPost subject:
stuartjdm
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the std pump wont cope id say i replaced mine before i got it mapped.
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Wed Mar 07, 2018 10:48 pm PostPost subject:
Wull
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Some good points there.......

It did actually cross my mind but I thought I had seen that the std pump could do 400bhp.

I removed the vac line and it went to 3.2 bar.

I attached a line from the spare wheel which I set @ 1 bar and the gauge went to 4.2 bar so it appears that the fpr is working.

So fuel pump, fuel filter......
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Fri Mar 09, 2018 5:25 pm PostPost subject:
stuartjdm
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My filter is on the end of the pump in the tank and was a bit of c*ck to do Laughing
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