1990 F150 4.9L 6cyl
Thanks for all replies in advance. My son has an F150 4.9l straight 6 that we cannot figure out what is wrong. It does not have any power and you cannot get past 40 out on the road. Compression is 150 on all cylinders. Replaced the ignition control module, idle control, TPS, wires, plugs, cap & rotor, fuel pumps, fuel filter. I'm not sure what else to check. We did check fire to the fuel injectors. Can you tell if an injector is working properly by unplugging it and see how the engine runs? We really need help on this.