Fuel pressure starting problem
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Fuel pressure starting problem
I have a 92 F-250 351w, dual tanks. The motor has been rebuilt and runs very well once I get it running.
My problem is the cold start. After 6 or 8 attempts the motor will turn over and after 15 seconds or so of sputtering all is well. I have checked the fuel pressure at the rail and seem to have found the problem, but the cause is elluding me.
Engine off pressure is only 10 to 12 psi (fuel pump grounded, constant on) and it will not build up any more but does not leak off for at least 15 mins. Once the engine is running, I have 45 psi and when the engine is warm the pressure stays an even 42 psi. (It does not leak off here after shutdown either). Restarting within 1/2 hour is fine.
The filter is new, but I have removed and checked it anyway, no clogs or flow problems. I am running on the rear tank only, since the front tank seems to have a dead pump. (0 psi, and when running switching the tanks will kill the engine)
Any ideas where my problem is?
Thanks in advance for your help.
My problem is the cold start. After 6 or 8 attempts the motor will turn over and after 15 seconds or so of sputtering all is well. I have checked the fuel pressure at the rail and seem to have found the problem, but the cause is elluding me.
Engine off pressure is only 10 to 12 psi (fuel pump grounded, constant on) and it will not build up any more but does not leak off for at least 15 mins. Once the engine is running, I have 45 psi and when the engine is warm the pressure stays an even 42 psi. (It does not leak off here after shutdown either). Restarting within 1/2 hour is fine.
The filter is new, but I have removed and checked it anyway, no clogs or flow problems. I am running on the rear tank only, since the front tank seems to have a dead pump. (0 psi, and when running switching the tanks will kill the engine)
Any ideas where my problem is?
Thanks in advance for your help.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
Sounds like low voltage or bad ground.
If it holds fuel pressure after you remove the ground or shut off the engine than the check valves and the shuttle valves in the fuel delivery module are OK.
Try replacing the fuel pump relay and check the voltage at the fuel pump plug.
Also check the fuel pump ground on the radiator support.
LxMan1 did you find out why my posts are being delayed?
If it holds fuel pressure after you remove the ground or shut off the engine than the check valves and the shuttle valves in the fuel delivery module are OK.
Try replacing the fuel pump relay and check the voltage at the fuel pump plug.
Also check the fuel pump ground on the radiator support.
LxMan1 did you find out why my posts are being delayed?
