Wondering if someone could please give me a clue. Have a 89 F-150 I-6 with dual tanks with no start/ hard to start fuel problem. Started having problems day after towing wifes car home with a couple hard jolts from her foot heavy on the brake( dont know if this is related). Problem is when key is turned , low pressure pump in whatever tank selected stays on. Engine hard to start, and if started, needs gas pedal to keep running, CEL on, dark/ smokey exhaust. Switching tanks back and forth for a while, sometimes the CEL will go off, runs on its own, no smoke( maybe idle little rougher than normal) Have changed high pressure in-frame pump, pressure regulator, fuel relay, filter. Have checked fuel pressure on rail 50 psi no start, 45 psi running. What tells low pressure pumps to cut off? Seems it will start only when low pressure pump cuts off normally(about 1 in 10 start tries) Please give me your thoughts. Thanks all!!!

 

The pumps cut out when the press. builds up to useable press.
It sounds like one of your injectors is stuck open bleeding of the press. and the flooded cyl. is causing your rough idle and smoke.

You might be able to smell some gas in your oil. try turning your key on for a few sec. then pull your plugs and see if a cyl. is wet.

 

Well first I would pull the codes and see why the CEL light is coming on... second what does your pressure do when you rev the engine? I take it its EFI, is it EEC-IV and do you know where your connector is? my 86 acted similar and it turned out to be the coolant temperature sensor, it was reading -40 and dumping all that extra fuel... but anyway the first place to start is why that light came on.

 

mikemike98, Don't think its injector related because fuel pressure will hold in fuel rail. about 50 psi(turning key on, then off) pressure doesnt bleed off. I may be wrong, but will hold that thought. mdstud,thanks for the reply! The truck is EFI, EEC-IV. The fuel pressure will creep up afew psi while giving it the gas. What connector are you talking about? I,ve tried to read the codes but had a hard time with this but will try to read them again. Where is that sensor you had trouble with? Could my EEC-IV be going bad? thanks guys.

 

I have a 1988 F-250 with 460 V-8, EFI. The worst problem I ever had with this truck was an intermittent stall, no re-start situation. Often times it would not restart for 12 hours at a time. Took it to the dealer a couple of times - no codes. They kept it for several days, the shop foreman drove it back and forth to work, but it never did it for him. The shop foreman was pretty sure that the fuel injectors were flooding when this problem occurred, but did not know why. I was told to hold the gas pedal to the floor and try to start it if it stalled and would not restart. That did work to get it restarted and it would usually run fine for a while. Finally, one day I started going through every connection and every vacuum hose I could find. Sure enough, both hoses on the cruise control system had holes in them where they curved or touched anything. I had the dealer replace those hoses and that fixed the problem. By the way, they were careful to use only the exact same original equipment spec hoses.