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Uprated Fuel Pump + Stock Fuel Pressure Regulator = Overfuelling?

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Old 25 September 2005, 04:22 PM
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mlite
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Default Uprated Fuel Pump + Stock Fuel Pressure Regulator = Overfuelling?

Hi!

Can't find the specific post on this.. do i need to get an adjustable FPR if i install a Warlbro 255ltr/hr? Would keeping the stock pressure regulator mean overfuelling?

This would be on a standard WRX(stock ecu) only, with full decat(maybe a boost controller in the future). Give any advice

Thanks!
Old 25 September 2005, 05:49 PM
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axgt_bwaii
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i had a friend who fitted a uprated fuel pump to a standard fpr and it blew it and made his car flood till he fitted a uprated fpr.

stew
Old 25 September 2005, 09:31 PM
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The O/E fuel regulator on your car should cope, no problem with the Walbro pump.
Old 25 September 2005, 11:30 PM
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Jolly Green Monster
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SHOULD being the key word..

Sometimes they are fine, other times it over fuels when the fuel consumed by the engine is low.. like idle and cruise.. this is because the standard fuel pressure regulator is over powered by the pump and the fuel pressure increases in the fuel rail.

Simon
Old 26 September 2005, 10:32 AM
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morpheous
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Have read quite a long thread on here about using a smaller capacity walbro as 255 is an overkill ?



Originally Posted by Jolly Green Monster
SHOULD being the key word..

Sometimes they are fine, other times it over fuels when the fuel consumed by the engine is low.. like idle and cruise.. this is because the standard fuel pressure regulator is over powered by the pump and the fuel pressure increases in the fuel rail.

Simon
Old 26 September 2005, 12:30 PM
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Tone Loc
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I have had a 255 pump and OEm pre97 regulator working together for 3 years. No problems at all, think it's pot luck if you will be ok on a pre 01 car but post 01 should be fine.

Tony.
Old 26 September 2005, 12:58 PM
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Jolly Green Monster
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but surely you have mapped around it Tony?

Simon
Old 26 September 2005, 01:13 PM
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Tone Loc
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No, orginally it was on the standard ecu.... and having to go back standard after selling the apexi and it still has the same AFRs as pre Walbro.

Did you know the Fuel regs for pre97 and post 97 operate at very different fuel pressure (according to teh subaru diagnostic manuals for each version), so pressume they are completely different regs. Maybe that has somnething to do with it.

Tony.
Old 26 September 2005, 01:20 PM
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lol..

Also some years have the drop to 9v little black box and others don't..

My 96 UK had one, 97 Type R Vlimited has one, 96STi2 doesn't.. cannot remember from other pumps I have fitted..

Obviously if it has the 9v dropper in and you remove and fit more powerful pump then more likely to over power fpr.

Simon
Old 26 September 2005, 01:22 PM
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BVM
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I run a walbro 255lph (p/n gs342) pump on my '02 WRX. It lowered my IDC but the AFR stays at the original 11.2 @ WOT.
Old 26 September 2005, 05:41 PM
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Originally Posted by mlite
Hi!

Can't find the specific post on this.. do i need to get an adjustable FPR if i install a Warlbro 255ltr/hr? Would keeping the stock pressure regulator mean overfuelling?

This would be on a standard WRX(stock ecu) only, with full decat(maybe a boost controller in the future). Give any advice

Thanks!
Fitted mine the other night. Walbro 225... no difference apart from a bit more noise. In time for my remap next month
Old 26 September 2005, 06:39 PM
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I cant hear my Walbro but then I put a NVH 'sock' over it.
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