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post #1 of 8 (permalink) Old Jul 6th, 19, 5:43 PM Thread Starter
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Todd
 
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fuel pressure

Hey everyone, I installed a fuel pressure gauge on my dual feed line to check the pressure and it is 12 psi at idle, I thinks it's too high. Why is it at 12 psi, if too high how do I lower the pressure? This a 454 engine, mechanical fuel pump, brawler 750 carb.

Thanks
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post #2 of 8 (permalink) Old Jul 6th, 19, 6:01 PM
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Do you have a regulator inline with the pump and is it electric or manual
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post #3 of 8 (permalink) Old Jul 6th, 19, 6:05 PM
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Sorry didn't read it all the only way to lower the fuel pressure is to have a regulator. And 12 is way high. I run mine at around 6.5-7. It should have a return that goes back to the tank beings it is a mechanical fuel pump
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post #4 of 8 (permalink) Old Jul 6th, 19, 6:15 PM Thread Starter
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Todd
 
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Re: fuel pressure

that hose is capped off that goes back to tank, not even sure if that line back to the tank is still there, maybe I should get a fuel pump without return line.
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post #5 of 8 (permalink) Old Jul 6th, 19, 6:27 PM
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The return line needs to be in place if there is no regulator bc it sends what fuel is not being used back to the tank that's how it regulates it
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post #6 of 8 (permalink) Old Jul 6th, 19, 10:47 PM
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Gary
 
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Re: fuel pressure

factory fuel pump are self regulating via the diaphragm springs. they can go bad and cause pump pressure to increase. plugging the return line will up the pressure a bit but
not enough to cause flooding. ive seen plenty of factory pumps with the return blocked over the years. it just works the spring a little harder. performance pumps are set to a higher pressure and need a regulator
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post #7 of 8 (permalink) Old Jul 7th, 19, 7:25 AM Thread Starter
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Todd
 
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Re: fuel pressure

I think the diaphragm is bad causing excessive pressure. I am going to change fuel pump. I ordered a carter M4530 fuel pump. I hope this does it.

What will happen if I leave it with 12 psi? the 454 runs good, doe not seem to affect it, the only thing that I noticed that I was having trouble setting the floats, the brawler has sight glasses, I think the high pressure was causing that
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post #8 of 8 (permalink) Old Jul 7th, 19, 9:57 AM
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rick
 
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Re: fuel pressure

My 454 with a 3310 750 holley was running really rich, I put a gauge on and had 12+ so I bought IIRC AC Delco pump and it did the same so then I added a regulator before the pump and set it to 6-7 lbs. and it seems fine, I also had the carb rebuilt.


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