So i have been trying to diagnose a sputtering/hesitation issue and have recently replaced the fuel filter, air idle control valve and the TPS. This weekend I was driving on the highway and she almost completely died. I was cruising at about 70 and suddenly i loss power but the car did not shut off. I dropped from 70 down to around 45 MPH and then she regained that power. This happened numerous times on the way home. At one point when i loss the power i would pump my accelerator to see if i could get gas in the line and after a few pumps it would catch and then backfire. Scared the **** out of the wife so i ended up pulling off the highway and took backroads on the way home. Even during that part i would loss power and then it would accelerate again. I just bought a new fuel pump today and I'll install that tomorrow but i just don't want to replace a part that isn't causing the issue. advice on were else I could look at?

 

Before replacing anything, you could rent a fuel pressure gauge and verify fuel pump is doing it's job.
Pressure should be 35-45 psi for V-8 engine.

Do you have anything heavy on the ign key that could be causing momentary loss of ignition?

 

So I have.the 5.8 v8. Where is my plug in location to check my fuel pressure?

 

Driver's side top of engine.There is what is called a schrader valve, looks like a tire valve, that the fuel gauge is screwed on to.
Pressure is checked at idle and approx 2000 RPM. Gauge is disconnected after engine is shut down System should hold pressure when shut down.

 

Is under the hood top of engine drivers side or do I access it through the inside?

 

You might have to remove the air cleaner assy (2 little screws up front and 2 hose clamps at throttle body) no big deal. But still easier than removing doghouse and everything on it. Engine can be run with air cleaner removed to do test.One of the easier things to do on the engine.lol
Just stay away from the fan blades, they have no conscience.

 

I was finally able to locate it. Had to remove the air cleaner to see it but did my test.

I don’t know if I did it correct or my connections werent tight enough but it did leak some fuel when I ran the test.

I did it first with just the key in the on position and it read 10pm I and then when I ran it with the car started it climbed to 20 but did leak some fuel. I know with it leaking some fuel that will sku the results but am in the right direction?

 

The pump must maintain a consistent pressure and if the leak is small that could be the same as engine running. There should be an "O" ring inside the fitting that screws on to the fuel rail. Either the "O" ring is missing or the nut was not turned down tight enough.

From what you tell us so far ,sounds like fuel pump may have a problem. Not a job for one to tackle with out the right tools and equip. Tank has to come down, if has a lot of fuel in it , can be pretty heavy. Should have replacement pump or entire module before starting job.

 

I am going to make sure its tight and re do the test.

So i know i have fuel pumps in the tanks as well as an external one that is above my fuel filter located along the drivers side frame under the drivers door. That is the pump i am looking to replace. I have a duel tank club wagon and i can be in tank 1 or tank 2 and the symptoms stay consistently bad. I am hoping this does the trick so that i don't have to drop the tanks.

 

Your suspicions sound good to me and I agree with your logic.. Just make sure to wear some eye and hand protection even if only changing the pump on the rail.
When all done , would like to know what the pressures are, thanks.