Fuel pressure adjustment question

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fishy68

fishy68

Tyr Fryr's Inc.
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Ok I'm about ready to fire up the Cuda and I got the Holley blue pump all wired up and plumbed to the carb and have a pressure gauge and regulator inline. Back when I bought this system I talked to Holley's tech line and they told me to set the regulator at 5 to 5-1/2 lbs for the 750 carb I'm running. (I thought this sounded a little low but who am I to question them, they built it.) Anyway I put power to the fuel pump and no matter how much I backed the regulator off I can't get the pressure below 9 lbs. I'm sure I'm turning it the right way (I'm backing it out) because if I go the other direction (screw it in) it goes higher. Now I'm doing this with the engine shut off. Does the engine need to be running to set the pressure or did I get a bad regulator?
 
sounds like a bad regulator to me. If the carb is getting gas which would mean its not from air trapped in the line that's all it could be. I have the same stuff and I have mine adjusted to 6.75 psi engine off ( and on). Could it possibly be the gauge? I had a bad autometer fuel gauge that I had to replace, too.

don
 
I thought it should read the same regardless if the engine if running or not but this is the first time I've done this so I thought I'd ask here just in case I was wrong. The carb is getting fuel. I'm leaning more to the defective regulator too. I wish I had another gauge to try because it is real easy to change but I don't have one. I have another regulator to try but where I have it located it isn't real easy to change but I guess I'm gonna have to try it and see what happens. I'd rather do that than have it force the carb seats open and flood my new engine and wash down the rings.

Thanks for your input Don
 
If the pressure guage returns to 0 psi when everything is shutdown and depressured then the guage is probably fine and your problem is most likely the regulator.
 
demon seed said:
If the pressure guage returns to 0 psi when everything is shutdown and depressured then the guage is probably fine and your problem is most likely the regulator.
Click to expand...

Yeah it go back to zero. Another reason I think the gauge is reading right and the problem is the regulator is the fuel pump is rated at 14 lbs. wide open and when I crank the fuel pressure reg. all the way up it goes to 14 lbs. I'm going to a metal meet and when I get back this afternoon I'm going to swap out the regulator.

Thanks guys.
 
I have an aeromotive regulator\pump and mine goes back to zero when the car is shut off. I also noticed it has some idiling issues, like its running out of fuel. I have it set for 7psi for my 750 DBL pumperand I havve been messin with it all day and just getting more frustrated

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The only pressure that matters is the running pressure and under WOT.Holleys need to keep at least6-7 lbs on them to fill the bowls at idle.Now you do not mention if by setting it at 8-9lbs if the carb is flooding its self? Is the fuel pump unloading the seat?,and dumping gas into the motor? Where is the guage mounted in the system,on the regulator or at the carb? What size line are you running?Mrmopartech
 
Mrmopartech said:
The only pressure that matters is the running pressure and under WOT.Holleys need to keep at least6-7 lbs on them to fill the bowls at idle.Now you do not mention if by setting it at 8-9lbs if the carb is flooding its self? Is the fuel pump unloading the seat?,and dumping gas into the motor? Where is the guage mounted in the system,on the regulator or at the carb? What size line are you running?Mrmopartech
Click to expand...

It don't seem to be flooding or overloading the seat. I was just concerned since this is a new subject to me and I didn't want to wash down the rings in my new engine. The gauge is mounted in the fuel line near the carb. The fuel line size is 3/8 all the way from the tank to the carb including the tank pickup. I didn't have a chance to change the reg. yesterday afterall. Will get it tomorrow.

I still think there is a problem because I just noticed when I energize it with it backed off all the way sometimes it goes to 9 lbs. and sometimes it goes to 11-12 lbs. Something just don't seem right about that so since I have an extra I'm gonna try it.
 
Well guys I swapped out the regulator and it works fine now. Aparently the 1st new one was bad. Thanks for all the replies.

72Dustyer mine drops back to zero when I shut it off too. My buddies Chevy pickup also goes back to zero when he shuts it off so that must be normal. I think it must be bleeding back through the pump. I can tell you why your carb isn't idling right. Your car is on it's side!! Just joking!!
 
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