Hey everyone. I got a Holley 750VS that's giving me problems. Every time I do a WOT run and shift from first to second the car just falls on its face and never recovers. It bogs A LOT like it ran out of gas. Another thing I noticed at idle... if you just floor it, it stops for a second.. then revs up. Any idea why it would be doing this ?!

 

The second gear bog is probably just what you said it is- running out of fuel. Put a remote fuel pressure gague on your car. T it in as close to the carb as possible (after any filters). Duck tape the gague to the windshield temporarily if you have to, but make sure you can see it while making a run. I bet you find that fuel pressure takes a nose dive at the top of 1st gear and the engine starts to sumble soon thereafter.

A stock in-tank pump can usually feed a healthy carbureted small block IF IT IS IN GOOD SHAPE (many are not). A block-mounted mechanical pump by itself will not be able to feed a hard-launching high HP engine, regardless of it's flow rating- the draw from the tank is too long for it to draw enough fuel through against the hard acceleration of the first 2 gears.

The other hesitation is likely an accelerator pump issue, and unrelated to this one.

 

You what's funny though... ? I borrowed my friend's 850CFM double pumper for about a month and ran it. I never had ANY of these symptoms with it ! I took it off because my gas mileage was waay down in the single digits. lol