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Discussion Starter · #1 ·
Hi I was just wondering what the difference is between a 255lph Walbro in tank pump and a High Pressure Walbro 255lph in tank pump. Obviously high pressure but why would I want this? Do I need this or is the regular 255lph pump good enough for my plans for my car(see sig).Thanks:cool:
 

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Discussion Starter · #2 ·
bump
 

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use the gss342 if you are going to run nitrous; especially since you are going to do the headswap and use nitrous. the 317 peaks at ~60psi and the 342 at ~90psi. gasoline isnt an ideal gas so PV does not equal nRT in this instance! higher pressure....more fuel will be there when needed...
 

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I worked with Mike from Walbro on this issue directly. The higher pressure pump does not deliver more fuel. The computer will also attempt to stabilized the pressure. The real problem is that the seals in the aspirator assembly have a tendency to blow out at higher pressures. Then what happens is that fuel system can't deliver enough fuel at max throttle. I can show you the pictures of my aspirator seals two weeks after using the 342. Walbro also had another unit with the same problem. The problem is caused at startup when you turn the key to on, the fuel pump cranks up to 60lbs+, then the car turns over and the computer then stabilizes the system. Unfortunately, during that startup, the seal goes.

Eventually, Walbro even built me a custom aspirator to solve the problem. It did help but those pumps aren't designed for a returnless system and can't adjust pressure fast enough. My suggestion would be to get the pumps that Steeda is now carrying but you will have to reburn your chip.
 

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rconaway said:
It did help but those pumps aren't designed for a returnless system and can't adjust pressure fast enough. My suggestion would be to get the pumps that Steeda is now carrying but you will have to reburn your chip.
He has a return style system (96). The 342 will be fine for that. I am running a 342 on a 99 returnless system and no problems so far. I am running a chip so maybe that is helping out. It seems some people have problems others dont.
 

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It probably won't matter for a 96 other than the seals get old but with a return system, the pressure can't go up during startup. However, on a 99, if you turn the car to the on position for a feew seconds before you start the car, you are taking a chance that the 60+lbs that will be created in the system will blow the seal. I have seen two instances of it and Walbro said they had heard of others and were waiting till the assemblies came in to check them. There is absolutely no benefit to the 342 over the 317 pump. I have 3 of them in a box that are almost new that we tested extensively. The correct solution for large horsepower in my opinion is to change to a returnless system or use the Steeda pumps. The Walbro 317/342 pumps are not designed for returnless systems.
 

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Discussion Starter · #8 ·
So the 317 will work fine with the nitrous? :confused:
 

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I'm also using a 342 pump on my 99 Mustang GT with no problems either. <knock on wood> I do notice the fuel pressure jump up prior to starting but I usually wait a few seconds for it to come down before I crank the engine.
 

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Discussion Starter · #10 ·
Whoops! I meant will the 307 255lph 60 pso pump work fine for my application?:confused:
 
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