Fuel system questions

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Jul 27, 2006 | 04:33 PM

cbloss

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Fuel system questions

I have a 1999 Chevy 5.7L 350 engine that I am swapping into a 1979 Chevy 3/4 Truck. I am on the fuel part of the project. I have done a lot of searching and talked to a guy at autoperformanceengineering.com.

I have purchased a gas tank out of a 1987 TBI Chevy truck, so it has the baffles, and I believe it uses an intank pump.

I have been searching on this board, and it seems to be the common consensus to use the Walbro 255lph. I am not sure if I should get the high-pressure version or not. Anyone have any insight on this?

Also I thought I would need a fuel pressure regulator, but the guy I talked to @APE was fairly certain there was one built into the fuel delivery system. Is this true?

Thanks
-Chris

Jul 27, 2006 | 05:27 PM

leonpiper69

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From: levittown PA

what did your new motor come out of? you might not need a walbro pump, but if your useing an lx based engine you will need high presure. the tb motors only run at 9-12 psi the lsx motors run much higher . i know my f-body ls1 runs at like 60 psi. i dont know what the truck ones run at. it might be the same. the good news is that the tank you bought, the high presure pump should drop right in there(same physical size just diff pres). but make sure you replace all that regular rubbber fuel line . regular fuel line will not handle the presure. you can use regular FUEL INJECTION HOSE. its twice as expensive as regular gas line (@ 2 bucks a foot) but it will hande the presures. hope that clears it up some.

Jul 27, 2006 | 05:29 PM

leonpiper69

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From: levittown PA

oh! and the reason i said you might not need a walbro is if your new motor is stock , then a stock pump will work fine . the higher volume is only nrequired for higher hp applications.

Jul 27, 2006 | 10:14 PM

cbloss

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The engine came out of a 1999 GMC Yukon Denali, but I do not have the fuel pump from the vehicle.

Jul 27, 2006 | 10:30 PM

G-Body

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Are you sure its a 5.7L and not a 5.3L? The LSx series motors never had a 5.7L motor in a truck and being a 99 it should have had an LSx.

If it is an LSx series motor then it runs at 58psi of fuel pressure and the 99`s will definently have a regulator built into the rails. The feed line is 3/8" and a 5/16" return.

Jul 27, 2006 | 11:29 PM

cbloss

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Yeah, 5.7L for sure, junk yard I got engine from could have told me wrong one the year, might be a 1998.

Jul 28, 2006 | 12:01 AM

G-Body

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From: Downers Grove, IL

Does your motor have the Throttle body on the front of the intake like the attached pic? If it does not then it it is a GEN I SBC based vortec 350 at which point my knowledge of the motor vastly decreases. But I do know that the GEN I vortec motors run at a lower fuel pressure, don`t have an exact number though. I think they still have a regulator on the fuel rail but I am not 100% sure.

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