Under load my V8 engine does not rev freely above about 4,500 RPM. What can be the cause of this apparent fuel starvation?
Check for blocked fuel filter first. I experienced a problem with the fuel injection pump located inside the fuel tank. When cold the pump worked normally and engine easily ran to redline. When warm the fuel pump failed to deliver full pressure under heavy load and engine coughed and spluttered between 4,500 and 5,000 RMV, not reving any higher. When I removed the fuel pump and measured its resistance it was mostly 0.9 Ohm (specifications say 0.2 to 3 Ohms is normal) but when the pump was turned I found a spot where the resistance was 19 Ohm, clearly indicating a failure inside the pump. A replacement fuel pump restored full performance. BTW, normal fuel delivery pressure at idle is 196-236 kPa (2-2.4 kg/cm, 28-34 psi) and under load is 265-304 kPa (2.7-3.1 kg/cm, 38-44 psi).
