Small Block & Big Block Chevy Specific - Need a little help, motor is acting like its running out of fuel.

hey guys, well i changed the carb on my motor from the 600 to the 650 dp and i have a problem. It has done it with both carbs so i know it isnt the carb. After i run the truck hard for a little bit it starts to sputter and will cut off. It wont restart for about 10 min. It acts like it is out of fuel. The new carb has a fuel pressure guage on it and it dosent even register 1 lb. The fuel pump is a stock replacement and there is an inline fuel filter (glass) that after it starts acting up is only 3/4 full. I was hoping changing the carbs would solve my problem but it didnt. The motor is a 355 w/ flat top pistons, TFS twisted wedge heads, 230 duration cam, 1.5 rollers, holley street dom. intake, 650 dp carb, hooker long tubes w/ dual flowmasters. It has a new gas tank and im running 93 octane. Thanks guys, it is about to drive me nuts. :bang: Oh it has stock ignition w/ new wires and accel plugs.

no ideas?

Sounds Like You Are Vapor Locking.after It Cools Down It Starts Back?

I had the same problem with my 85 it has a new block with no mechanical pump hole drilled and when i bought it it had a weak solid state pump and they pluged of the return to fix it a bought a holley pump with regulator(sucks) and used the return line to keep fuel moving and cool.Hope this helps!

I have been wondering about the vapor locking. Im not sure if i follow what you are saying though. The botom end is new and it i used a stock replacement fuel pump from napa. They left a bolt out of the front of the block, (the one that goes into the fuel pump cavity) and when i was getting on it pretty hard it would squirt oil all over the front of the motor. I read in hot rod about it needed to be pluged and after i did that the oil leak stopped. There is no telling what else was left undone. Oh the dip stick came on the wrong side of the motor also. Anyway thanks for the help, ill try and reroute the fuel lines.

A stock pump will not supply a modified engine for extended romps.

I would agree with a vapor lock, or even the pump losing its prime.

I would step up with a aftermarket mech pump, then see how this condition is.

wrap your fuel lines,any near the motor.some kinda heat wrap.anything under hood.

stock mechanical pump won't hold on even a 14 second motor in my experiences. Even a 6 psi aftermarket carter dropped to 3 psi on a 2-3 gear shift on a full pass at times. Go with a bigger pump (either mechanical and/or electrical) and check your fuel line routing from tank to pump to make sure no areas are close to exhaust. I'd consider an upgrade to 3/8" line if you still have stock 5/16" as a possibility as well.

Just my $.02

Derek

thanks guys, i am getting another fuel pump and i will wrap the lines as well. I've been looking at the pumps and it looks like either the holley or the edelbrock. I dont want to run a regulator so that will factor in. Thanks for the advice guys.

Charles

it would be better to run a holley blue with regulator.can handle what ever hp you put to it.