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Fuel pump issues?

1K views 5 replies 3 participants last post by  brian42 
#1 ·
I have a 2001 f-250 7.3 with 193,000 miles. when I turn the key to the run position, the fuel pump will run for about 20 seconds before it shuts off. if I wait for the glow plugs to cycle and then try to start the truck it will crank for 10 or more seconds before it starts and when it starts, it will lope really bad a couple times and then idle normal. if I start the truck without letting the fuel pump run it will fire right up and idle normal. I have also disconnected the fuel pump and let the glow plugs cycle and it starts right up then too, its only if you let the fuel pump run. It does this whether the engine is cold or hot. The truck is all stock. It did have an auxiliary fuel tank and the previous owner was running WVO. But I took the tank out and put the original set screws for the fuel rail back in the heads. I’ve cleaned the ebp tube and sensor, and replaced the CPS. I tried it with the ICP disconnected and it still does it. what could be causing this?
 
#2 ·
It's possible the regulator is bleeding down too quickly. I personally believe every 7.3 owner should be running a fuel pressure gauge. If you had one, you'd be able to see exactly what is going on as you try to start the truck. Low fuel pressure can cause injector damage, so I'd really suggest you test it.
 
#4 ·
That's great, but what is it doing when you first turn on the key? By the time the wait to start goes off? That was your original concern and what you needed to test.
 
#5 ·
When I turn the key on, the fuel pressure jumps to 65 psi and stays there until the fuel pump shuts off. When the fuel pump shuts off, the pressure slowly bleeds back down to about 5 psi.

I did notice that when it starts hard, it doesn’t fire until the oil pressure gauge on the IC starts to read pressure. And it lopes until the pressure gauge gets to about where it normally sits and then the idle smoothed out.
 
#6 ·
You should not bleed fuel pressure that fast. The pump runs eary to prime the fuel system to adequate pressure and should maintain it there. I'm not too hip to all the pieces parts in the fuel system but something is not holding pressure like it should.

Oil pressure needs to get to 500 psi before the truck will fire an injector.
 
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