I am using the Holley 12-804 regulator, 1-4 psi for my tri-power. This was set by my dyno guy to 2 psi for me, while using his fuel pump. I transferred the fittings and gauge (which was working fine) from my old reg when I got it home. Now, if my fuel pump runs less GPH than my tuner's, will this require me to reset the reg? Or once it's set to a pressure, it's set at that pressure no matter what the pump is pushing? I'm asking because on start up last night, the gauge is reading "0". Before I go out & replace the gauge or screw w/ my tuner's reg settings, I want to know if this could be a possible issue with the reading. Thanks!
it should be right on, or close at least.... Maybe the plumbing is wrong? or the pump is not working? or something like that. Pictures of your regulator installed on your car might help,
Same place, plumbing, etc as my old one...just swapped them. But like I said, my gauge isn’t working, at all. Needle not jumping, dead. It seems to be getting decent fuel to the carbs though, runs ok. Unless I screwed something up swapping the gauge. I was debating whether or not to replace the gauge. I still want to be able see the pressure. Knowing that the reg wouldn't need adjusted helps. Thanks. Sent from my iPhone using The H.A.M.B. mobile app
What pump are you using on the car? and what did the engine guy use? Also is this the same gauge that he used, or a different one? Getting a gage to register at that low pressure, could be iffy, if the gauge has a rather high maximum pressure number.
I've had nothing but trouble with the 1/8" pipe thread pressure gauges from the supply houses no matter the brand. Check it with another gauge before assuming the worst.
Loosen the lock nut on the regulator and turn the allen head screw clockwise to increase pressure. I have the same Holley low pressure regulator and found that the gauge would read accurately for a short while and then it would gradually drop to zero. This happens because the engine bay heat effects the fluid. I removed the gauge, poured out the glycerin fluid, refilled it 1/4 full with silicone brake fluid and now it reads accurately at 3-4 psi. Give it a try. The only purpose of the fluid is to dampen the vibration of the needle. QUESTION: Will Holley regulator work properly when mounted vertically?
Mine is the red 97 gph holley. I'm not sure what he used on the dyno and he typically does race engines...so not even sure his pump is as low gph as mine. Not sure of max on the gauge, I'll take another look at everything tonight when I get out of work.
If it's running ok, I'd leave the regulator alone. You didn't answer my question about what gauge he used, vs the one you are using
just as an aside, I have an older fuel pressure gauge like this that I temporarily install on the engine to set the regulator, then I remove the gauge for normal driving (it looks like crap on a period engine). If I go on a road trip, I take the gauge with me, to help trouble shoot ignition problems that act like fuel system problems.
Looks like Teflon Tape on the gauge threads. If you got any across the end of the fitting you could have a blockage and at 2 psi you wouldn't want that. Actually you don't want that at all. When using tape sealer I use a razor blade and clean the tape off at the first thread. Could be worth looking at. You shouldn't be afraid to re set the regulator. Different pumps make different pressure. Incoming pressure will change the reg setting. Also, I see some kind of sealer on your Temp sender. If your temp gauge don't read right that right there could be your problem. They need to Ground and sealer is an insulator. The Wizzard
I really have no idea. I should've just skipped putting the gauge on since he said it was set by the sounds of it.
I used high performance thread sealer wire brushed the old off as much as I could & only ran it around maybe two threads in the middle of the threaded area, not near the edge, wiped off excess. I don't use tape on my fuel fittings. My temp gauge seemed to be reading ok.
From the picture that adjuster screw looks like it is backed fully out, since you are troubleshooting run it in a few turns and see what happens. We shouldn't be able to see that many threads, if it was set at 2#'s that'd put the screw about halfway in.
I hate to go against the advice of Squirrel, but a pressure regulator set with the flow of one pump will have to be readjusted when used with a different pump, unless both pump's output's match, which is unlikely. If you're really unsure about messing with the adjustment from your tuner, you could always just keep track of where the adjustment is now, and how far you turn it in, and you could always turn it back and set it to the same point if you see no increase on your gauge. I would just turn it in a bit and watch for a response on the gauge. If it doesn't respond, than the gauge probably is at fault, and you can back the setting back to where you started; and then get a new gauge and start over. The setting for fuel pressure is to ensure you have sufficient flow to meet the needs of the engine under heavy load & high rpm's, while not be so excessive as to unseat the float valve and flood the carb with excess fuel. If the pressure is too high fuel will weep from the throttle shafts and create a mess on the manifold. You'll see it and you'll know it's too high. If it's too low the car will surge at speed and under load. This isn't some kind of black magic that has to be perfect, the pressure just needs to be between those extremes.
That depends on the flow from the pump. As the flow from the pump varies the adjustment on the regulator will have to change too.
This is all good info to think about. I’ll start adjusting the screw this weekend & go from there. Thanks again for the replies. Sent from my iPhone using The H.A.M.B. mobile app
The flow from the fuel pump will change depending on how much load is on the engine. At idle, only a very small amount of flow is present, at high rpm and high load a lot of fuel will be used. The function of the fuel pressure regulator is to maintain the same pressure throughout this varying flow. As Jim has mentioned, you need to use a gauge with a very low pressure reading. Gauges are not reliable in the first few percent of their sweep.
It appears that your guage is quite a bit below (~2') the level of the carb inlets. If its close to 2', the actual pressure at the carb level is going be .75~1 psi lower by virtue of the head loss. You can either move the guage up to the level of the carb inlet or compensate your adjustment for the head difference. Making the situation even worse is you are trying to only achieve 1-2 psi at the guage. In the end, all the matters is what the needle/seat see
Good point from yellow dog. It's difficult accurately measuring these low pressures. You can calibrate your pressure gauge with water and a length of clear tubing by suspending the tubing vertically with the gauge at the bottom. Since one atmosphere of air pressure is 14.7 lbs per square inch, or 32 feet head of water, it follows that one psi will be equivalent to about 2.18 feet of water. So by simple math, we know that the water column at 4.36 feet will be two psi on the gauge, 8.72 will be four psi etc. You can mark the hose at these lengths and fill with water to the marks, and calibrate your gauge with a pretty high level of accuracy, since it is easy to measure length precisely. This is why low pressure gas is measured in inches of water column. Jeez, as I reread that it seems really complex. Oh well, if it's helpful great, if not, ignore it.
This was a timely post, I just installed the same regulator a few nights ago. Mine also runs better with the lower pressure but my 15 psi gauge is reading zero as well. The reg is set at 2.8 psi from the manufacturer I will probably experiment with a little lower pressure for my 97's. You can see the zero pressure reading at idle I fault the gauge accuracy at low pressure. Most of these gauges I think are all from the same company in China and they are made with different logos. I ordered a 10 psi gauge with no fluid inside to calibrate my regulator but like Jim said above, I probably will not run it past shake down as it looks like ass.
I think the gauge by Dickster is the only low-pressure one available that isn't absolutely ugly. I've been thinking about getting a couple. They are really reasonably priced.
I have the same issues with a 15 lb Russell gauge and the same regulator. I set mine to read 3psi when it is cold and ignore the 0 reading when it warms up. D
I picked up a very nice old 10 psi US made gauge on ebay, but it is very difficult to find these gauges because of the way the search function works. You will get about 99% useless results. I think the 10psi, 1/8NPT inlet is the most useful gauge for this application. The lower gauge range means that the 2-3 psi range is more accurate. A lot of the vacuum gauges will also have this scale, as they were often also used to test fuel pump output pressure.
Some of those little liquid filled gauges have a pressure relief valve that you can open to equalize the pressure when they get hot.
Old thread, but I can help with the topic. The Holley regulator uses a diaphragm and a check ball balanced against an adjustable spring. Problem is that under very low flow conditions, like at idle, the check ball spends much of its time on the seat stopping the flow, with an occasional small bounce that lets some fuel through. When the ball is on the seat, the pressure gauge is reading the float bowl pressure, which is nearly zero anytime the float needle is open. When driving, the fuel flow increases to where the check ball is off the seat and the gauge reads the expected system pressure.
I had the same trouble, I don't know if the gauge was bad or not, I tossed it and replaced it with a low pressure one, never any problem after.
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