93 F150 Fuel Problems
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Freshman User
Joined: Apr 2005
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From: Madisonville, KY
93 F150 Fuel Problems
My problem stems from Changing a stock 4.9 out to a older non roller 302 HO.
Now that everything is finally bolted up and in place I can't seem to keep it running longer that 30 to 40 seconds. It seems to be starving for fuel . The stock fuel pump is running up to a pressure regulator set to 5.5lbs. Can here the pump prime the line when key is turned but I am unshure of how it is set up to run, does it run all the time or intermitant. Can I wire it to run all the time or do I need to replace the pump with an electric pump. Does anyone know of a website to get the wiring diagram for these trucks.
Thank you for your help.
Now that everything is finally bolted up and in place I can't seem to keep it running longer that 30 to 40 seconds. It seems to be starving for fuel . The stock fuel pump is running up to a pressure regulator set to 5.5lbs. Can here the pump prime the line when key is turned but I am unshure of how it is set up to run, does it run all the time or intermitant. Can I wire it to run all the time or do I need to replace the pump with an electric pump. Does anyone know of a website to get the wiring diagram for these trucks.
Thank you for your help.
Posting Guru
Joined: Jun 2004
Posts: 1,781
Likes: 1
From: Central NY
I'm assuming your still fuel injected here.
The 4.9 should have been running at 55psi, the 5.0 will use about 35psi so I think you can see why its starving for fuel at 5.5psi.
The computer will run the pump for 2 seconds when you turn the key to on and then turn the pump off. The pressure should hold within 5 psi for 30 seconds after shutoff. If it doesn't then you have a leak, possibly injectors.
If it detects the engine running after that it will turn the pumps back on and keep them on until you (or something) kill the engine.
Your local parts store should carry the Haynes or Chiltons manual for your beast whick also contains the wiring diagrams.
I hope this helps,
Popa Tim
The 4.9 should have been running at 55psi, the 5.0 will use about 35psi so I think you can see why its starving for fuel at 5.5psi.
The computer will run the pump for 2 seconds when you turn the key to on and then turn the pump off. The pressure should hold within 5 psi for 30 seconds after shutoff. If it doesn't then you have a leak, possibly injectors.
If it detects the engine running after that it will turn the pumps back on and keep them on until you (or something) kill the engine.
Your local parts store should carry the Haynes or Chiltons manual for your beast whick also contains the wiring diagrams.
I hope this helps,
Popa Tim
Last edited by Popa Tim; Apr 17, 2005 at 09:16 PM.
Posting Guru
Joined: Jun 2004
Posts: 1,781
Likes: 1
From: Central NY
Okay check the carb spec, the last time I used carbs, on my AMX, they were 8psi but I think 5.5 should be fine for a streetable setup. So that leave the fuel pump is not running with the engine. It sounds like you have the computer still wired up since the pump primes for the 2 seconds, you have your options open to you. Either wire the computer back in or wire in a fuel switch. The computer uses a signal from the distributor to determine if the engine is running btw. I beleive its called PIP.
Cheers,
Popa Tim
Cheers,
Popa Tim
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