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Walbro 340 stock fuel system. 70 psi fuel pressure?

Old 04-27-2012, 09:03 AM
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Default Walbro 340 stock fuel system. 70 psi fuel pressure?

Installed a new fuel pump. Now the fuel pressure is 60psi with the key forward. And 70psi at idle? Wtf?

The fuel system is all stock 99 trans am lines, bucket/regulator and the LS1 rails with the dampener built in.

The regulator should be holding the same stock setting regardless correct? I did not think the pump was that oversized that it puts it out of range.

Also is it possible to turn the fuel pressure up/down via HPtuners and using voltage? Maybe the tuner tried getting all they could from the stock pump and now this one is running on high all the time. Just a theory may have no relevance at all.

Help is greatly appreciated.
Old 05-01-2012, 05:43 PM
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so reg can keep up. put a c5 fuel filter in line it has a reg built in. take out factory reg and just return to that port
Old 05-01-2012, 06:53 PM
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x2.....
Old 05-01-2012, 08:25 PM
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Typically with a 255 pump, you car would have about 62 at idle.

You either have a bad gauge or a problem with the return line or regulator.
you could have smashed the return line above the tank or got something in the return line partially plugging the regulator.

The Vette regulator will work essentially the same as the Camaro regulator.
Not much to gain by changing it
Old 05-02-2012, 12:38 AM
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The stock regulator cannot keep up with all that flow and you are building up pressure in the dead end system.
Old 05-25-2012, 06:57 PM
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My isthe same, racetronix kit with a 255 pump in tank, gauge reads 65-70 psi all the time. Car needs a tune and is running rich, can it really cause a big problem being that high?
Old 05-26-2012, 08:35 AM
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Talking Could be..

Originally Posted by ls1fst98
My isthe same, racetronix kit with a 255 pump in tank, gauge reads 65-70 psi all the time. Car needs a tune and is running rich, can it really cause a big problem being that high?
of the reasons for rich is the injector flow rating is incorrect, at the higher fuel pressure...
You could:
A. During the tune, change the IFR, to reflect the added flow resulting from the higher psi.
B. Change the fuel system to allow for the correct pressure.
Old 05-31-2012, 03:56 PM
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How much hp is the 340 rated to?
Old 05-31-2012, 09:18 PM
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I just bought a fuel sending assembly with a racetronics pump and hot wire for my camaro so here is my question. What do I do with the regulator that is inside of the assembly. Do I take it out completely or leave it in. Also I'm using an adjustable reg on my rails so I was told to run my return from reg to the aluminum block that is on the drivers side of car in the back. I was told to plum it into there. What do you guys think?
Old 06-01-2012, 05:52 AM
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Remove the in tank regulator.


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