So, i leave for the track this afternoon, and get about 15 minutes up the road when the car starts running like absolute crap. It feels a lot like there is a giant vacuum leak somewhere in it. I get out and check everything, but its all good. I hook up a vac. guage and it reads 15hg at idle, and rises above 20 at part throttle. NO problem there. Start driving again and it's still acting up. At this point i notice the fuel pressure is down to about 4.5. i turn the regulator all the way up and psi returns to about 7. I drive a bit furthur, still doing it. Pull over and check FP, it's down to 5 again. At this point I'm lost, and i'm pissed.

The car is acting as though the valves are floating at ALL RPMS under load, and it wont even move unless it's brought to WOT, and it's rediculously lean then. I could give the car just a tiny bit of gas and it would run perfect, but as soon as i give just a tiny bit more, it bogs like crazy and wants to die. I think it's the fuel pump. I don't think it's ignition related, but i haven't ruled it out completely. I popped the valve covers off and checked for any loose rockers, but they were all good.

I pinpointed the exact moment this happened, at it was when i free revved it to about 5000 rpm. After that it all went to hell. I've done this about 30 thousand times and nothing has ever happened. the valves did NOT float when i revved.

I'm pretty sure its the pump, but i have no real way of telling. Any help or advice you can give me would be greatly appreciated. I'm sure i haven't given enough info, so just ask anything you need to know.

mods:
355 (stock bottom end)
Crane 272H cam (.484" lift, 216* dur, 112* lobe)
Trick Flow heads (1.47 springs)
RPM AIR GAP intake
Speed Demon 750 DP
Holley mech. fuel pump (SHOULD flow 7-9 psi)
Holley regulator.
Total timing is about 38-39*

Eric

 

If your pump is mechanical i think you may be right and your pump took a crap. If its electric id say your filter is clogged and can't flow enough fuel to rev past idle.

 

Flow test the pump. A good pump should deliver at least 1 quart in 30 seconds (or 1 pint in 15 seconds). If not, , you may have a pickup sock filter that is plugging, low fuel level, restricted line or filter, or a failing pump.