I’m running out of fuel pressure halfway down the track. 5/8 fuel line all the way with a 155 gph pump. Regulator set to 8.5 but at wide open it’s down to 3psi or lower. 670 hp drinking thru a 950 Quick fuel. Filter was checked and cleaned. According to some math online it says the pump is big enough BUT I don’t think so. any thoughts?
I like 250 Mallory for over 600hp. 5/8 line could be why you are seeing drop. 1/2 will maintain pressure better at the expense of some volume.
I had mallory CP pump years ago and constantly had trouble with it. Could not get help from Mallory so I switched. I now can read some reviews on there stuff and it looks like I was just unlucky. Mine was used before I had a new thing called the internet.
What reg does it have ? 5/8 line is quite big ,that's a big column of fuel to push .I ran a Mallory 250 for years was great ,with a #8 line #10 return off the reg.. Running an A1000 now I just had to replace it after 16 years, not so bad really .
Mine did a similar thing from the pump getting air bubbles. Once from a hose leak sucking air into the line, it wouldn't leak a drop of gas on the ground though, once from the tank pick up sucking air bubbles. Do you have jet extensions on the Holley jets? Do you have the big needle and seat assemblies? Side or center hung float bowls? The internal pressure on the 5/8" tube walls are greater than a 1/2" tube if the pumps can keep up and no compressable bubbles present. (more internal square inches for the pressure to push on) Fuel filter screen holes to small or not enough of them (too efficient or plugged)? Faulty regulator, faulty gage reading. Your going too fast for your hood scoop opening and the carb quits working? That does not cause the low fuel pressure dummy, strike that idea.
