Cliff's Quadrajet Parts and Rebuild Kits
Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: Daniel828 on October 14, 2018, 09:02:13 AM
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I have a 66 olds cutlass with a 455. Why does it run out of fuel, when running it hard , on the 2-3 shift?
I was told to add an electric fuel pump to help the mech pump. But why does it starve for fuel?
I replaced the 5/16 line with 3/8 line too
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What carburetor part number are you using on the big 455?
What have you done to it?.....Cliff
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Sorry. I forgot that info. It was in my first post but it wasnt posting incorrectly
The carb is a 7040240 with your rebuild kit 71 jets and DA secondary rods
The motor has forged pistons, 228 duration cam at 50. .500 lift, headers with exhaust crossovers blocked and 2.07 intake valves and 1.68 exhaust valves. Just had heads rebuilt this summer
I bought a Holley red pump to give me a little boost but I haven
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Haven’t installed pump yet. Upgraded fuel lines from 5/16 to 3/8 too
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It runs out of fuel because of insufficient fuel delivery. That carburetor number with a .135" N/S assembly should easily stay full on hard runs at your power level.
I'm not much of a fan of using an electric pump to feed a mechanical pump but I've seen some folks do it with decent success. That deal didn't work at all for my car way back when I was using a 455 only making 1hp/CID.
A lot depends on the pick-up location in the tank and if it gets uncovered or not on a hard run with traction.
The length, size, number of bends etc with the fuel line to the pump is also a player here. For sure it is easier to "push" fuel 14' or so than to pull it that far when you find good traction and the car is pulling really hard thru the lower gears.
You are also feeding 455cid, so fuel consumption is great at full power. In any and all cases the correct fix is to keep the carb full on hard runs. I'd start out with the Holley Red pump and see if things improve.
You can also try a larger fuel inlet seat, we have them clear up to .149" although I'd recommend no larger than .145" for that carburetor with the stock size float in it unless you have a regulator......Cliff
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I’ll give you a call cliff, and order the larger n/s. Also, I’m at a 1/4 tank of gas. So maybe the pick up is starving for fuel? An electric pump wouldn’t help there anyway, right?
The sending unit is located at the front bottom of the tank
Thanks cliff
Dan
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Fixed!!! I installed a Holley red pump and no more fuel starve problems
I usually don