fuel pressure problems

[Firebird454]

OK, this is my fuel system. I have a sumped stock tank that has about 10" of -8 line to a sytem1 fuel filter then into a procomp black pump. After the pump I have -10 to my holley big port regulator. From the regulator to the carb is -8. The problem is when I first start it up I have plenty of fuel pressure, then after about 15 minutes of running the fuel pressure drops and continues to drop even after I regulate it back up. I just ordered a new holley black pump in hopes of a cure. Any other ideas what may cause this if it turns out not to be the pump? The reason I am not certain its the pump is because I bought it new and only used it for a few days, then let it sit for a year or so.

[BLUE66]

Do you have a liquid filled psi gauge near the engine?????
If so, take it off and get one that is not filled.
Or at least if it has a rubber plug, empty it.
The liquid filled gauges read incorrectly above room temperature.
At underhood temps they will usually fall down to around a couple psi.
T another gauge in to prove this if you want.
I doubt you have a delivery problem.

Although you should be feeding your pump with -10.
But this has nothing to do with your fuel psi. at a standstill.

Brian

[OUTLAW1]

if your tank vent is plugged it will lock up and make the pump work very hard and burn the pump up also will slow it all down! also the fuel filter you need to check and see if its a steel screened filter (sitting for a year untouched the thing will rust and plug easy(been there done that)

[UPdragracer]

definetly sounds like the gas cap is not vented very well or there is a ton of shit in the tank . I worked on a 1974 big block nova one time that damn near sucked the tank collapsed ha ha ha .

[Jim]

I think I saw/heard you yesterday! :D

I think I have a spare blue pump here somewhere if you need to try that.

[Firebird454]

Yep. That was me. Thanks everyone for the replies. I just ordered a new pump and it should be here Wednesday. My tank is new and I've rinsed it out several times after I had the sump welded on, but I will drop it one more time maybe take it to Oshkosh radiator to have it cleaned really good, I don't think the vent is clogged because I went out of my way to make sure it wasn't , but since I'll have it out I will double check and I think I will rout it different. While I'm at it I think I will get a better gauge and mount it in the car using an isolator.

[70Maverick]

How about a return? That will help too.

[BLUE66]

Did you verify your fuel pressure loss with a different gauge yet?????
I don't know how many times I've seen this, and lots of money thrown away when it's a $20 gauge.

[Firebird454]

I haven't really touched the car in a few days. I plan on trying a different gauge out side the engine compartment. The only reason I think its more than the gauge is because once the pressure goes down the engine acts like its starving for fuel too. I ordered the new pump because I was told by Eric Johnson of competition products where I bought the procomp from that they are junk.

[Jim]

Yep. That was me.

I texted Chuck right when you drove by asking him if we knew who that was. :D He said----"probably not, that guy had a mullet" lol

I had a sneaking suspision that was you. It sounded pretty good going by. :3gears