Hi guys , I have a 1996 f150 2wd 4.9l , it starts good and idles fine but sometimes when it's running at 60 - 70 mph it will drop out like it lost fuel pressure , when I step down on the gas peddle it just spits and sputters like it's not getting any gas. When I pull over it will idle just fine but as soon as I step on the gas it sputters. Any ideas what it might be? I put new fuel pumps in about a year ago and I've checked the fuel pressure regulator and I don't detect any gas , it should be ok. Someone suggested it might be the idle air control valve but it idles and starts fine. Any help would be great! Thanks

 

You need to put a gauge on the fuel rail, the 4.9 runs a petty high pressure because of the relatively small(14lb) injectors, you should see upwards of 55-60psi with vacuum removed from the regulator(engine running) and at least 45psi with vacuum attached. Pressure should always increase towards the max when the throttle is opened quickly or if the engine is under load at speed(never drop), and the system should hold pressure after the motor is shut off, pressure slowing bleeding off overnight is OK.