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2001 Subaru 2.5 RS-T BRP
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359 Posts
Discussion Starter · #1 ·
What should the fuel pressure be with a Walbro Fuel Pump (255lph)?

I was running a walbro and it used to be over 50 psi...
I just installed a new Walbro since I had a new laying around and after the install, it barely makes it to 50 psi mark...

I thought that OEM fuel pump pressure was around 38psi, and with the Walbro it would go up to 55psi or so.... (not while boosting of course).

I couldnt find any threads on this, which seems even stranger... or my brain is not working at all from all the fuel fumes.
 

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2015 WRX
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2,350 Posts
Stock fuel pressure is ~41 psi at idle. Fuel pressure will change according to manifold pressure though.

I will be running an Aeromotive FPR with my Walbro 255 since the stock regulator (at least on the older JDM motors) cannot keep up with the flow rate of fuel being delivered. You're experiencing a higher fuel pressure since the regulator cannot pass enough fuel to maintain the desired pressure.
 

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2001 Subaru 2.5 RS-T BRP
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359 Posts
Discussion Starter · #3 ·
Im not worried about the additional fuel pressure... I tune the car with a Standalone.

Im actually concerned that compared to my previous walbro, this one is running lower pressure by 5 psi or so.
Any other thoughts
 

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overdeveloped beater
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8,335 Posts
You haven't said if both Walbro pumps are of the same capacity....or what the % tolerance is for the Walbro pumps, or if you've made any other changes to the car. If your return line has reached the limit of fluid flow, your pressure will rise regardless of the FPR setting, if the pump is strying to flow more.
 

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2001 Subaru 2.5 RS-T BRP
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359 Posts
Discussion Starter · #5 ·
Both pumps were the same... and nothing changed. The car still runs a stock FPR, and any other modifications are meaningless since the only thing that changed was one fuel pump for the other.

The fuel filter is new, so I cant really think of any reason why the pressure could be lower...
 

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Premium Member
overdeveloped beater
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8,335 Posts
The new pump isn't flowing as much. Try comparing the new and old numbers as a percentage if you can. If it's just a couple lbs.....it's likely within tolerance.
 

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2001 Subaru 2.5 RS-T BRP
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Discussion Starter · #7 ·
It seems like its around 5psi... which is not that bad... but I thought it would be pretty much the same... I guess I'll give it a week or so, and richen up the entire table a bit.
 
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