Just took my roadster for a last shakedown ride before LARS. Glad I did, it started popping through the exhaust during acceleration again. Checked the fuel pressure gauge and it was down to one pound. I had set it at four when I installed it a couple of years ago. Thought I had the problem fixed when I changed the dial pressure regulator that would swell and shut off the fuel, for a new Holley regulator. Well the Holley reg. just started doing the same thing. Don't know if it is the California fuel or what. Anyway don't install one of these or any other fuel reg. without a gauge to check your pressure. It can change. Gary
Is it near a heat source? I'm sure heat could have an effect, but you would hope it takes a whole lot of heat to change it that drastically. I have one of the Holley type with a gauge right after it.
I've searched this a lot, 1/2 rodders on here have had that problem, I had it after 20 mins,not several years, others have no problems at all, some suggest to run a 3/16 return line to tank. I have run a return back to inlet line and seems to be working, but car is not yet finished, so not 100% sure yet.
I have the same issue. Holley regulator, liquid filled gauge, electric pump near gas tank. However, my gauge is located at the carb, and when all is cool, the gauge reads 4 psi. If I drive the car and get everything all warmed up, the gauge reads zero, but the car runs fine. The guys at Jeg's told me it is the liquid filled gauge, and when they get hot, they read all wonky or not at all. Thinking about trying a non-liquid filled gauge, but I know the needle is gonna bounce when the fuel pump is pumping. I guess I could also mount the gauge near the regulator, and I suspect there is not enough of a pressure drop from the rear of the car to the engine, so it might work. Any other ideas short of mounting the gauge on the front fender (just kidding)?
I have the exact same issue .......... turn on the fuel pump and my Russell liquid filled gauge is adjusted to and reads 3 1/2 pounds .......... start the motor and eventually the gauge goes to " O " ........... which is absolutely wrong ..........I do not want to run a return line and I am too dumb to figure it out ...........tp
Had the same problem with liquid filled gauge on my last 32. When warm would read zero. Wrap an ice pack around it and reading would come up. Rerouted fuel line so gauge was on the firewall no more problems. Drove me nuts for a while cause it was a blower motor and ran well but always worried about running it lean.
Research the liquid filled guages. Plenty of info out there. They need burped and I'd bet yours have a rubber plug on the back to do this. They need burped every time they heat up. The luiqid gets hot and causes a false reading much lower than actual
I went up on the firewall with mine and over to a fuel block with a liquid filled guage- roughed in for now.Let the testing begin. Not used to this new set-up so you get two pictures for the price of one !!
It took me three tries to get one good Holley regulator with out physical defects...A couple day sit will alter the pressure, to high or low at initial start up..Tap the regulator and it returns to set pressure and is fine till next long sit...This is with CT fuel, can't see why it would be the problem...
I just got my Chevy II running, blown 427 dual AFBs and a holley blue pump in back, with a Holley regulator up front. I have a non-liquid filled pressure gauge on the rear carb. The needle vibrates about 1 psi all the time, which doesn't bother me. It buzzes right around 7 psi like it should. I've only had one Holley regulator like that go bad, it was many years old, had been sitting for years unused, and when I installed it it leaked like it had a hole in the diaphram. Took it apart, it had a hole in the diaphram. btw I got the pressure gage from McMaster Carr for about ten bucks. with video.
Dang, I've never considered the dynamics of a liquid filled gauge. I know I've had at least one car that had me puzzled because of it. Wonder how many regulators have been tossed due to this. http://www.marshallinstruments.com/faqs/detail.cfm?id=26
heat is a big problem with liquid filleds as it works against the bourdon tube mechanism when the liquid expands , on the OT race car we have a 1" br*** tube extension( the stuff you buy at a hobby shop for model airplanes) epoxied in to the top of the autometer gauge ( in dash mounted with a isolator ) that has a small 1/32 pinhole in it to self regulate the pressure and not allow the glycerin to vibrate out .the rubber plug just plain ****s as it still leaks at times , but we are now replacing the gauges with dry units as we really do not need the dampened needle as who reads it when the ride is 10sec long . we just point all the needles to the straight up position when the engine is running so you see it out of the corner of your vision . as for holley regulators had a problem a few years back with some when the company was having money issues , but not in the last 2-3 years . as for the Holley knock offs , had many blown diaphrams in them
Depending on what the diaphragms are made from, the garbage gasoline we have to deal with might be attacking it.
It looks like your regulator is by the tank, I always put my regulator as close to the carb as possible and have never had any regulator issues. I had the liquid gage issue described above and just drained the liquid and it works fine now. You can see the Blue regulator behind the water pump and the gage on the fuel block
I found that adjusting the Holley regulator while the engine is running gives you an accurate reading.
I had the same issue. I changed the pressure regulator and the problem came back. I then thought my mechanical SBC fuel pump might be the cause, so I changed it. Still had the problem with erratic pressure. I would have never guessed that the liquid filled gauge was the culprit!
I've heard of more gauges giving false readings than regulators going bad! Problem is most people replace the regulator, instead of the gauge. If you really want accurate gauge readings you need to go to a remote gauge with sending unit, so the gauge is inside the car. The direct mechanical will almost always fail sooner or later.
had a SW fuel pressure guage *on* my dash fer 20 years in an airguide housing, like a small tach -- was still there when "Beulah" got killed in 2011 -- STILL works!
I'm having just the opposite problem. I installed a new pump and filter and the gauge is reading high. Car runs fine, but the fuel pressure should be 2-1/2, not 6+. I will order a new gauge based on the posts here.
Always check the pressure when it's cold, and compare to readings after the engine bay warms up. That will tell you if the gauge is failing.
The Jalopy Journal
