I'm working on figuring out my fuel delivery issues on my 85 GT 5 speed. I might have a defective fuel pump I'm struggling with, but I need some pointers to determine if I'm on the right track. Last time I went to the track, I was running out of fuel at the top of 3rd gear and into 4th. Since then, I have changed both fuel bowls to the center hung 4150 style to make sure I have plenty of capacity. It still starves for fuel up top, even in 2nd gear now. Come back home, pop the hood, and my fuel filter housing barely had any fuel in it.
So, I tested the fuel flow with the supply hose off of the filter and had it spraying into a gas can so I could see what the flow was like. Running the engine at idle, I get good, strong sprays of fuel. However, when I increase the engine speed to, say, 2500 rpm or higher, the fuel stream gets noticeably weaker and appears to lose volume big time.
Is this normal or am I seeing signs of a weak fuel pump? The stock fuel pump should be plenty of fuel delivery at 30 gph. Stock, this engine only needs maybe 18 gph if my calculations are correct. This pump is a stock replacement Carter that I bought from NAPA 5 years ago. The car does sit a lot though.
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