This week, I installed a fuel pressure gauge in the gas line near the carb. With an electric fuel pump, and a fuel pressure regulator, I wanted to more closely monitor the fuel delivery. With the key on, and the fuel pump pumping, I get a good reading of 3 lbs. When I start the engine, even at an idle, it drops to zero. Is this normal? I rebuilt the carb and it seems to have no issues. Seems to me, the float should close while idling, giving me a reading.
Doesn't sound right to me. Perhaps a photo of the set up so we can see the regulator, gauge tap and carb relationship.
This is common with glycerin fluid filled fuel gauges. The heat build up in the engine compartment causes the liquid to expand and the needle to drop to zero. I drained all the fluid out of the gauge and reinstalled it. The needle fluttered so much it would not give an accurate reading. Added a few drops of silicone brake fluid to the gauge and it then 'worked" better. You may have to play around with how much brake fluid to add. I bet DOT 3 or 4 brake fluid would also work. Give it a try. Here's some good reading. https://www.verociousmotorsports.com/Articles/VM-Articles-Fuel-Pressure-Gauges-Liquid-Filled-vs-Dry and https://www.google.com/search?q=flu...ome..69i57.10622j0j4&sourceid=chrome&ie=UTF-8
It has a new good quality electric fuel pump, a Mr. Gasket fuel pressure regulator (seems to work fine, doesn't leak, and the fuel pressure changes when I adjust it), runs great down the highway and at idle.
What kind of pump is it....is it a normal low pressure pump? if so, byp*** the regulator, see what happens. I have more experience with higher pressure pumps that require an external regulator, they don't behave like this.
Also, is it a high pressure or low pressure regulator? On the simple Holley in-line regulators there are different springs for different pressure ranges. If you're not using a Holley regulator, which Mr. Gasket regulator are you using? https://www.summitracing.com/parts/hly-12-807/overview/ IDEA: Switch the locations of your fuel pressure gauge and your "see through filter" and see if there is a difference.
I am using an "Autobest" F4027 low pressure electric fuel pump, and a "Mr. Gasket" 9710 fuel pressure regulator.
hmm, if it was me, I would adjust the regulator with it running and see what happens. or maybe try a different gauge?
It looks like that pump only puts out 4.5 PSI max and you have a regulator on it effectively killing your pressure. I don't know what carb you're running (looks like it could be a Holley), but even if it's an Edelbrock you shouldn't be using a regulator. Holleys like 6-7 PSI so that pump unregulated may not be enough.
What engine and carb are you running? Float doesn't necessarily close while idling. It just controls the amount of gas going into the fuel bowl. As fuel level in bowl drops so does the float allowing more gas in so as to maintain the required amount of gas in the fuel bowl the running engine requires. If your pump only puts out a max pressure of 4.5 psi, you don't need a regulator. If your pump was pumping large volumes of gas at a higher pressure your regulator might help reduce the flow so as not to overpower the float and needle valve.. Truth is, I have never heard anything good about the reliability of those "dial style" regulators It's just a diaphragm with an internal spring adjuster. Say "Goodbye" to that regulator. You may even find that without it your fuel presssure gauge will work. Here's some opinions on that regulator. https://www.jalopyjournal.com/forum/threads/do-the-dial-style-fuel-press-regulators-work.337452/ By the way, make sure your fuel pump is installed as close to the gas tank as possible and that there is a fuel filter between the tank and the pump.
Just read that thread. Regulator has to go! By the way, I am running a 2bbl Carter carb on stock 318 pulled from a '68 Barracuda. (I know, just like every sbc came from a Corvette!) It runs so good that I haven't had the heart to put a 4bbl on it yet. By the way, I replaced the Mr. Gasket fuel pump with Autobest unit based on reviews, before it failed. Thanks guys for all the replies.
I have the same problem regardless of the liquid filled fuel gauge I use. Both my fuel pressure gauges are quality (one is an Earl's). Those of you using Stromberg carbs know that Strombergs will not tolerate fuel pressure above about 3 pounds or the needle valve will come off its seat and the carb will flood. I use a low pressure Holly fuel regulator. Regardless of which pressure gauge I use, my fuel pressure is OK when I first start the engine, but after just a minute or so, the pressure starts to drop to almost 0, despite the fact the engine runs perfectly.
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