Been working on my 93 F250 7.5 L 460 EFI for a couple weeks. Started off with a sort of stumble/hesitation when giving it gas. Changed the front tank fuel pump with witted I think it was, AutoZone. New fram filter. New EGR and sensor. New TPS. Code reader only seems to tell me what I've messed with. New fuel pressure regulator. Also I don't seem to have any fuel pressure. Even checked the pressure at the new filter and the needle barely moved. I can hear both pumps running though. I did just move from WA to AZ so I kinda wonder if the huge difference in heat is causing something. Starts best when cold. Hopeless when its warmed up even a little. Idle goes from 1k to nearly dieing and back up a few times before it just dies. I have spark. My exhaust system has some bad leaks and may be leaking from exhaust manifold too. Everything I can think of points back to the fuel pumps which seem to be working. Any help would be greatly appriciated.

 

My experience says fuel pumps. I have never had good luck on these computer vehicles with FI using anything but OEM Pumps & Pressure regulators. My 90 Honda Civic pump went out & the shop put in an Airtex & it lasted only a few months. Dephi built OEM pumps for several manufactures. I have never had an issue with them. They built OEM pumps for not only GM but Honda & Toyota I'm told.
Can you check your fuel pressure at the filter inlet? If so what is your pressure. Do you have dual fuel tanks? Could you have a blockage in your switch over valve? That is why I say go back to the filter inlet.
Craig

 

I. I checked the pressure at the fuel filter an barely moved the needle. It does have dual tanks and both tanks run the same. The fuel selector valve does not exist on these trucks. They did away with that a few year prior to mine. It's actually a part inside the pump that switches when you select the tank you want to run off of. I did hear that Bosch is the only after market fuel pump that will push fuel at ford specs. Hate to drop a tank again when the pumps sound strong. I was wondering if the return line being capped off could cause problems. Ford's fix for a recall awhile back.

 

Not having return lines can burn up your pumps. Without them you over pressure your system. All FI systems use a continuous calculation of gas, with one exception that I know of & that system is on the Dodge V-10s I believe both the Vioer & I know the trucks because I own a 99 Dodge 2500 4x4 V-10. Why are the return lines plugged?
By the way WELCOME & come visit us on the Arizona Chapter board.
Craig

 

Not 100 percent sure its the return line that's plugged off. It is a fuel line tho. Ford had a recall on these because the return line went into 1 tank only causing over filling when the other tank was used. From what I can tell their fix was to plug it off.

 

Just a thought....... Vapor lock?