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Could very well be your fuel pump is on it's way out.

Any other symptoms

Does it smoke all when it begins to die.
Will it start up right away.
 

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I agree! test your fuel pressure. and check your air filter and fuel filter while your at it.
 

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Discussion Starter · #4 ·
fuel trouble with 6.9 IDI

I have changed the fuel filter. It will start 99.9% of the time with no trouble. The trouble starts when you're going down the road at higher RPMs, 60, 65 MPH then it starts jerking, cutting in and out like its starving for fuel. I put power directly to the fuel shut off, to eliminate a wiring issue. I'm wondering if it's sucking air, possibly injector O-rings? When you say fuel pump may be headed out, are you talking lift pump or injector pump? thanks for any input.
 

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I have changed the fuel filter. It will start 99.9% of the time with no trouble. The trouble starts when you're going down the road at higher RPMs, 60, 65 MPH then it starts jerking, cutting in and out like its starving for fuel. I put power directly to the fuel shut off, to eliminate a wiring issue. I'm wondering if it's sucking air, possibly injector O-rings? When you say fuel pump may be headed out, are you talking lift pump or injector pump? thanks for any input.
To eliminate both fuel pumps and move on to injectors, you have to test for pressure. Test after the lift pump and then after the injector pump. If those appear fine then you will need to flow test your injectors.
If there are issues with the either pumps The gauges will tell you. Something to think about if you get full pressure on start up and then it drops when your at wide open throttle you may have a blockage coming from the tank. It's really hard to say, till you start testing the fuel system.
 
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