EFI fuel pressure problem

[Russ67Scode]

So I put a few miles on the new BP engine without the turbo’s and after running for a while the fuel pressure drops the pump makes more noise  I have a  eliminator fuel pump with a return system AN-10 supply and AN-8 return , also the controller is set for fast speed at 3000 rpm  I got home with the pump making 1-10 lbs ! The tank temp at the bottom was 76 deg some of the fuel lines was 100 deg
Is it vapor locking ?

[jayb]

Where is the pump mounted?   If it is at the tank, below the bottom of the tank, it should be fine.  The Aeromotive pumps are pushers, not pullers, so a gravity feed to the pump really helps. 

Also, is your tank baffled, and if so is there a big enough flow of fuel into the sump?  Sounds like you are running out of gas...

[Katz427]

I would agree with Jay, if the pump gets noisy" er" I would agree,  fuel supply. I have an SDS computer running my EFI. One of the things I found was the tank likes a good sized vent when you really start pulling gas thru the system with a large capacity pump.

[Russ67Scode]

Pump is mounted tight at the tank the tank was full above the level of the pump. New stock tank with McRobb pickup
Funny thing I will try  was I hammered it and the fuel pressure went up to about 25 lbs from 10 just the opposite of what I thought would happen I will run the car with the fuel cap open and see if venting is my problem ;-)

[Russ67Scode]

Fuel pump pic

[mbrunson427]

Where is the pump mounted?   If it is at the tank, below the bottom of the tank, it should be fine.  The Aeromotive pumps are pushers, not pullers, so a gravity feed to the pump really helps. 

If I'm looking at your picture correctly, looks like the pump is mounted above the tank. Needs to be below the level of the sending unit.

[Russ67Scode]

Picture is deceiving the pump sits at about 1/2 on the tank and these problems happen even at a full tank    also I have ran this almost empty and haven't had the first problem     going to drive it a while with a few spirited hit and then open the cap and see if its in a vacuum

[mbrunson427]

But the fuel still has to go upward out of the sending unit to get to the pump. You don't want to go upward with the line until after the pump. I can see it cavitating in that section. The pump may be pulling fuel faster than the head pressure in the tank can fill the void.

Look at bullet point #3.
https://www.aeromotiveinc.com/wp-content/uploads/2016/10/111-0122-0revK.pdf

Hope this helps, I think it should.

[Russ67Scode]

I believe I have solved the problem. Got to looking at parts I have bought and the blue filter is the 100 micron filter and the black is a 10 micron.  Well the black filter is on the suction side of the pump !!
Now I wish I had put a ball valve on the outlet if the tank !

[My427stang]

Of course if the pump is making noise, and you found a filter/feed problem, need to fix that. 

However, many liquid filled gauges lose the ability to proper show pressure with heat.  It surprises me that your car would even run with that low of fuel pressure, so if the gauge is liquid filled and it's getting warm, you may have more pressure than you think.  Might want to put another gauge on it and see if you have really have a pressure problem or only a noisy pump/crappy supply problem

Also, if you are running a vacuum reference to the regulator, which you will need for boost later, make sure the regulator is adjusted properly for idle.  Vacuum will reduce pressure just like boost will tell the regulator to add more

Likely preaching to the choir here, but be careful if you have low fuel pressure and running it hard, EFI can go lean, injectors can't flow without pressure and especially when you start pushing air into that engine, requiring the regulator to tighten up a little, it can hurt things quickly.