Fuel pressure basics?

[Broncojunkie]

I'm having issues with fuel pressure on my pace car. It has a fresh 331, sumped tank, new braided fuel lines with return, a Holley return-style regulator, and carter electric pump mounted low just in front of the tank. All of this is basically brand new. My problem is that I am only getting 3.5-4 psi. Adjusting the regulator does almost nothing. If I loosen the adjustment screw to lower the pressure, it will go down to about 2 lbs with it backed all the way out. If I tighten it to raise pressure, it goes to about 3-4 lbs. I put a new gauge on it and readings are the same. What is the best way to narrow it down between the two? The parts stores only have junk and I'll have to order these parts. They're not exactly cheap, so if I can test them it would be better.

Oh, and all of these parts have probably less than 5 hrs run time on them. When I first started the car last year, it was showing 6-7 psi. I'm not sure when it started losing pressure, but it wasn't long after the initial startup. I just figured the gauge was bad. In fact, I used the pump to drain the tank today. Pressure seemed a little low, but otherwise pump the entire tank out with no issues. I hooked up to the regulator, so pressure was coming through the regulator itself.

[Broncojunkie]

Well, I believe I figured out my problem. Just another bad fuel issue from sitting. I've pretty much been dealing with this all week. Mowers, cars, even the neighbor's scooter. Just gummed-up old fuel. I'm also swapping the pump with a bigger Holley blue (14 psi, 110 gph). The smaller Carter pump was evidently taxed out with the slightest bit of blockage.

[erratic50]

Arg. Just fought this with my son’s F250. Bad fuel from a gas station

[Broncojunkie]

I thought I had it all figured out. Took the regulator apart and cleaned it, replaced fuel pump with a brand new higher-psi/gph unit, replaced fuel filter, drained tank (looks brand new inside), blew out lines, etc. I'm still only getting 3-4 psi at the carb. I even replaced the gauge thinking maybe it was bad.

[dynodon64]

Look for a leak ahead of the pump, inside the tank pick up tube. Could be sucking air.

[swearint]

It sounds like you should now have a spare gauge at hand, can you install it somewhere between the pump and regulator?

[Broncojunkie]

Ok guys. I finally figured it out. The pump didn't like the filter on ther suction side. It was a 40 micron. Holley says suction side needs a 100 mic or better, and 40 mic on the pressure side. I figured it would make a difference but I didn't think it would be that much. Pressure is great now and regulator doing its job.