fuel pump issues.

Hello, have you tried turning off the inertia switch for the fuel pump circuit and see if that shuts the pump off? That would help to rule out if the pump is getting power from another circuit it might be shorted to. The inertia switch on these is down on the passenger side kick panel. Its pretty easy to find, its just a 2 wire switch, looks like a button with two wires plug into the bottom, a Pink/Black wire and a DarkGreen/Yellow wire, they are 14 or 12 gauge, pretty heavy wire. But you can just unplug the switch and it should stop power from going to the pump. And if the pump continues to run, then you know its getting power from another source. The wiring harnesses in these trucks is pretty basic, we have an 01 as well for a spare vehicle, they are pretty reliable.
So pulling the relay didnt stop the pump from running? Is that what you mean by it was Ok?

someone had said to swap a known good relay to it which i did, is there another way to check a relay? i don’t have much mechanical knowledge

so if i disconnect the inertia switch and it cuts it off, that switch is bad?

No power runs through the switch to the pump, the inertia switch is a safety component. If you are in an accident and hit hard enough, the switch will open and stop the fuel pump from running. Disconnecting the switch will help to determine if the power is coming from the relay staying on, or if power is coming from a short to power somewhere else on the circuit. Ill post a wiring diagram of it for you. But even pulling the relay out, if the pumps stops, then you know either the relay is staying latched (On) or something is keeping the relay on, as providing a ground for it to stay active.

okay, so if i either disconnect that switch or pull the relay and it shuts the pump off then i might have a short or a bad ground?

Nope, lets start with the relay, if you pull the relay and the pump shuts off, then either the relay is staying latched when it is deactivated, (this happens when there is some carbon build up on the relay contacts internally), Or the relay control wire (which is a ground the PCM controls, Ill post wiring diagrams of that as well) is staying grounded by the PCM or that wire itself is shorted to ground somewhere. This is pretty easy to check with the relay out, you'll just need to check the control pin where the relay sits for continuity to ground with a multimeter.

okay, does the truck need to be running when i pull the relay? sorry for asking so many questions im just not really mechanically inclined

no worries, ask as many questions as you need to, thats why we're here. The truck doesnt need to be running, if you hear the fuel pump staying on after the key is turned off, just start with pulling the relay, and we'll go from there.
We can even start to track down where the power is coming from by checking for voltage at certain locations.
This first diagram is battery power coming from the fuse through the relay and out to the pump.
The 2nd diagram is still that same DarkGreen/Yellow wire from the relay, you can see it runs to a Splice (S111) where power goes two ways, to the inertia switch and then the pump, and also power goes to the PCM where it monitors whether the relay is actually suppling power to that wire. You can see at the inertia switch the wires change colors, DarkGreen/Yellow going in and Pink/Black coming out.
The 3rd diagram shows that PCM monitoring wire.

Im assuming the fuel pump is staying on all the time?

no the fuel pump isn’t staying on when the keys not on, it’s only when the keys in the on position. sorry i should’ve specified that in the description

Well technically the fuel pump should only come on for about 2 seconds when the key is first turned on, this is to prime the pump and get the fuel pressure up to spec. The PCM will then wait until it sees an RPM signal to turn the fuel pump relay back on again and allow the engine to start.
Are you having an issue with starting at some points?

it stays on even after 2 seconds it doesn’t ever cut off. sometimes i can go out there and it’ll start but if i cut it off it won’t start back until after a little bit but sometimes it won’t start for a few hours even days

This can be a bad relay, even if it looks ok or the fuel pump has a bad spot on the armature.
Have you tried a different relay yet? On these trucks there are a few relays that are the same in the engine compartment fuse box. I am pretty sure the AC Clutch relay or Trailer Tow Relay is the same as the fuel pump relay, so you can swap that and see if the issue continues, if not then replace the relay, if it continues to be an issue with starting, then we will need to diagnose the fuel pump and its wiring.
Do you have a multimeter and test light to do some testing with?

i have put a different relay, it did the same thing. i’m not sure if i have a multimeter but i think i have a test light

You can check for power right at the inertia switch when the truck wont start.
So you are not hearing the fuel pump when the starting fault is happening? It is very common on this trucks, you have pretty high mileage at this point.

i can hear the fuel pump staying on, i even put a brand new one and could still hear it constantly. i even swapped the old fuel pump back in and it starts more frequently but still won’t start right after being started

Go and find the inertia switch first so you know where its located. That way when the fault occurs you can be ready and go right to the switch to check for power.

Did you replace the fuel filter as well?

yes sir i did replace it as well

Ok thats good. Has the check engine light been on at all lately? The pump staying running and the starting issue sounds more like a wiring issue, since we're kind dealing with two potential faults here. It would be good to check fuel pressure when this is happening, but this will get into more technical type testing if youre comfortable with that. You will need to pick up a fuel pressure gauge, harbor freight has a cheap kit you can get and Ford has a very easy port on the fuel rail where you can screw on the adapter. If you look around the fuel rail where the injectors are, you will notice a small cap screwed onto a threaded port. Its difficult to miss. Ford makes this testing pretty easy compared to other makes.

i’m not sure if the cel even works or not, half of my dash doesn’t really work like the speedo and blinkers but when i first got the truck it wasn’t having any issues starting. i do want to note it did get bumped into with a front end loader i can add a picture i dont know if that has anything to do with the inertia switch

i’m not sure if you can really tell in the picture or not

Is that when the trouble started? Because that is what the inertia switch is for, a bump to the truck can definitely cause the switch to trip, maybe it only partially tripped, it kind of like a circuit breaker, if it gets tripped you just push the button on top and reset it.

Looks like a north carolina vehicle.

no sir this issue started about 2 months ago. i’ve had the truck over a year and a half now and it was running really good until it started doing all of this

This is inertia switch and reset button, give it try,

i tried to push it and it didn’t do anything, this is what it looks like

sorry the picture didn’t add

Yup, thats the switch, if you pull the carpet away a bit you will see the connector and 2 wires on the bottom of it, with these if I need to check the switch for whatever reason, Ill just keep it simple, I will check the voltage level on the Dark Green wire first, then check for the same voltage level coming out on the Orange wire. Most of time you can do this without even having to unbolt the switch, although that will make it easier, but I would grab a cheap multimeter somewhere, (walmart, autozone etc). You just need to read DC voltage and resistance in some cases (Ohms). So you can get a cheap meter probably for $20 or so, and this is Harbor Freight's cheapest fuel pressure gauge that does come with the Ford adapter, its the most common adapter out there.

In this case, since we really dont know if that inertia switch is ok or not, you can do a couple things here, you can unplug the switch and jump the two wires together, just make sure youre using the same or higher gauge because the fuel pump pulls some amperage.

You can also do a voltage drop test across the two wires while its plugged in and the pump is running, you should read close to 0volts, meaning there is no voltage loss on the switch itself. This is very basic testing, so dont let the terminology get to ya.

I would do the testing first before jumping the switch out, unless youre comfortable doing that, it would eliminate the switch altogether for now. But seeing what the fuel pressure is doing is important, this might be something completely different than we think, so its very important we test so we dont change parts that dont need to be changed. That gets expensive.
HF has a meter for $5, cant beat that,

So the truck wont start even when you hear the pump still running? I just want to make sure we're on the same page here.

Read through this guide to get an idea on fuel pressure testing. You basically just thread on the pressure gauge and key On first, make sure it gets up to 40-60psi. Put a shop rag around the fitting when threading it onto the fuel rail, some gas will come out, so we want to make sure theres a rag there to soak that up. Make sure its threaded on straight and down all the way.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

it starts, if i drive it or letting it run it won’t start right up it takes 15 minutes for it to start back up

That happens even with the new pump in?

I guess what I was really asking, is do you hear the fuel pump running when the engine wont start?

yes sir, well actually it took longer to start after driving when i had the new one in so we put the old one back in

and yes i can hear the fuel pump running

Ok, thanks. So it is possible we have more going on here than just fuel pressure. But it should still be checked and monitored while testing. These trucks only have a couple control modules in them, they are not super complicated.
It sounds like its heat related then, which could be any number of things, but we'll start with getting a pressure gauge on the rail so you know what the pressure is reading and can watch for any changes.
you have one of these 12v test lights also? I would pick one of these up as well if you go there. Just because I know the current flow for these test lights. I have a bunch of different test lights that all pull different amounts of current for whatever I happen to be working on. Some circuits can only take so much, especially when it comes to what the PCM can control,

okay it might be a day or so before i can get a fuel pressure gauge because i currently don’t have a job but what should it read on the fuel pressure?

The spec is 35-60psi, but I like to see them at least above 45psi, but since you do have a test light, you can still see if theres power at the inertia switch if you can get the truck to fault pretty easy. I think youre going to find there is power. If that pump is running,
Did you have to drop the gas tank to do the pump? I just take the bed right off the truck, its only 6 bolts and the whole thing picks right off the back, you'll need help but its much easier to do testing and/or swap a pump out, no need to drain the tank and drop it at all. I had to do a pump in mine not too long ago, and it was really fast that way. The 6 bolts are large Torx bolts, you can see them right in the bed.

okay so check the inertia switch with a test light to make sure it’s getting power after the truck doesn’t start and while the fuel pumps running? and yes sir i already have the bed off its currently off as we speak lol

Yeah, you wont be able to see what the exact voltage reading is, but make sure the test light is bright on both wires at the inertia switch. You can do the same for the connector at the fuel pump, put the test light in place the of the pump, that will help verify it has good power and good ground. The test light doesnt pull much for current at all, but its something you can check in the meantime.

You did get this guide to checking the fuel pressure too when you can?

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator