Fuel Pump Pressure

[williebm3]

83 3/4 ton 4 X4 w/ 350 that was rebuilt by someone else. Problem is that I have too much fuel pressure about 9 -10 lbs. Put regulator on it down to 6 lbs. and it was still overriding the needle and seat and flooding the back bowls. Have backed the reg. almost all the way off and it is still doing it. Have put 2 different pumps on it and they all do the same thing. Wondering what could be causing this? Never had this happen before. Any help would be great.

[williebm3]

Forgot to mention Holley 80457 carb brand new out of the box.

[VileZambonie]

What are you running for a fuel pump?

[williebm3]

Stock fuel pump. Have checked the fuel pump rod and is fine.

[Captkaos]

Your stock pump is putting out 9-10lbs in front of the carb?

[williebm3]

Yes. Straight out of the pump it is putting out 9 - 10 lbs of pressure. I have changed pumps and it still is putting out that much pressure. Wondering what else it could be. I have put a regulator on it and it still will override the back needle and seat on the Holley. Confused to say the least???

[team39763]

Is it possible that the previous owner wired up an electric efi fuel pump in the tank that comes on with the key?

[VileZambonie]

What are you checking the fuel pressure with?

[williebm3]

Do not think there is an electic pump in tank. When I got the truck the bed was not bolted down and I had to get the gas gauge to work. Only had 2 wires going to it. One for sender and one for ground.
I am checking with a gauge and have put a different gauge that I got from a mechanic buddy of mine. They both read 9 - 10 lbs. Just wondering if the cam could have something wrong with it on that lobe.
Other than that I am at a lost.

[Stewart G Griffin]

The 83 service manual says 7.5 to 9lbs without "vapor return line."  i'm assuming that means return line?

With return line it's 5.5 to 7 lbs.

i think the holley doesn't like that much pressure?

[TexasRed]

Do you have a return line? If so, maybe you need a different pump with the bypass. If not, maybe you need to add one and add a bypass regulator it can return the fuel to the tank that the engine doesn't need.

[williebm3]

Had return line pump on it when found this problem. Return line was plugged, not anymore put new return line on it and new pump with return on it. Then put Holley pump that I had on that was on race car motor so know it was good. That pump was putting out 6-6.5 lbs on that motor and jumped to 9-10 lbs when on motor in truck.

[78silver]

If you had a regulator on and cranked down to 6 lbs, and still had flooding I'd suspect a carb problem.  Leaky floats and crud in the needles and seats can cause flooding.  Check pressure between carb and regulator to verify regulator is working. 

[williebm3]

I checked pressure after regulator, that is how I set it to 6 lbs. I have since turned it down to about 5lbs. Have not tore carb apart yet to check needle and seat. Was brand new when I put it on, so I would not think that there would be anything in it but you never know.
Can you get a spring loaded needle and seat for a side hung bowl?

[jaredts]

I would call Holley next.  Chances are you've got a piece of garbage in your seat somehow.  You didn't run it without a filter or use old line after your new filter did you?  It is possible that the float was improperly adjusted at the factory, but I kind of doubt it.  You need to exchange your carb. or take the top off and check for trash in the seat/bowl.