Hello, love the site. I have a 2000 F150 with a 4.6 and am having an issue where fuel does not develop any pressure. So far I have replaced the filter, pump, and pressure regulator. When I turn the key on the pump runs, I have even wired the pump straight to the battery and run it, but no pressure accumulates other than a little gurgle from the schrader valve. When I unhooked the return line and put the line in a bottle, gas just flows right through. So my question is how is it supposed to build pressure? And am I forgetting something? Thanks

 

Well, today I found some more things out.
Using the key on engine off test on the scanner, I was able to confirm that the pump makes pressure at the rail, by letting the schrader valve spray all over me. IMMEDIATELY after pumping it has little to no pressure. So I checked the oil and yes, it is full of gas.
So now I am going to look at the injectors, yet another thing I have never done before. Has anyone had any experience with this, and am I looking in the right place?

 

The more i watch other people's threads get bumped, but not mine, makes me think I am in the wrong place for my question.

 

Folks may not understand exactly what you're asking. From what I read and maybe understand.....(1) you have fuel in your oil pan and (2) you think the injectors are the problem?

 

yes i do, or did.
Today i took out thhe fuel rail and zip tied the injectors down to it, cycled the key a few times and had none of them leaked during my redneckish leak down test. So while they were all like this, out of the cylinders, I tried the schrader valve, and boom, fuel pressure. Now i am confused again.

I now have fuel pressure, for now. I replace the injectors, the rail, and all of the hoses i had to take apart to do this. (Btw, camera phones are helpful).

I now change the oil, and filter(oh my).

I cycle the key a couple times to build pressure again, START it, it starts for about 1 second. Dies. Try to repeat the process, and once again it wont build pressure.

Now i know it will build pressure, with the pump and regulator, for some reason its letting go when i try to start it.

Thanks, im sorry for being so difficult to diagnose, but its my first ford and any idea is better than none.

 

I guess I posed too difficult a question. Thanks anyways, figured I would go here and make an account first,, because this site is helpful.

 

If I was to guess I might say the fuel pump is going bad.
here's a link to a thread with similar issues

https://www.f150online.com/forums/19...arts-dies.html

Maybe this will help you

 

Exactly! Fuel is supposed to flow back through the return line. That's how the system regulates (ie LIMITS) the pressure at the injectors. Either you don't understand how the system is supposed to operate or you're not explaining your concerns adequately. The first thing that you need to do is to get a mechanical pressure gauge connected at the injector rail. Then you can see if your f pressure is too high or too low and if the electronics are reporting the pressure correctly. If you haven't done that then you're wasting your time chasing problems that may not even exist.

One other thing, fuel is supposed to flow back to the tank via the return line pretty much at ALL times, not only to control the pressure but also to keep the fuel cool at the injectors and to help cool the injectors themselves. Besides engine heat, they also generate a lot of heat themselfes when they are rapidly pulsed open and closed.

 

OK I think I understand your problem now. Let me see if this is right; your engine HAS fuel pressure at first and does start but then loses fuel pressure and dies. Correct? If so then I think I can explain what's going on. I'm not positive if Ford does this or not but MOST most F.I. systems supply fuel pressure when you first turn the ignition the ignition but only for a very FEW seconds after the engine starts. It then checks certain conditions such as oil pressure and if it doesn't like what it sees then it shuts off the fuel pump and the engine. It sound like this is what is happening. Put an electrical meter of the power input of the fuel pump and find out. If you lose electric power after the engine starts then that's the problem. You (or someone) is going to have to look at a service manual and find out what your model looks for before it allows the fuel pump to continue running after start up.

WHY did you change your oil and filter????? I think that's one of the things to is misleading everyone here.

 

^^^

 

Thanks for the replies. Yes it did build pressure until I tried to start it, now its back to not holding pressure ever. It will not hold pressure at all. When doing a key on engine off test and running the pump, i can push the schrader valve and it sprays a ton. If I do the same test, and push the valve after the pump is done running, there is little to no pressure.
So after eliminating so many things, it seems at least one injector is grounding out and staying open. Unfortunately I dont know where to begin to look.

 

I feel like you are over thinking your problem and chasing your tail. If an injector was as you say " staying open" that cylinder would fill with fuel and your engine would hydro lock (the piston would stop moving and stuff would break) on the compression stroke.

By your own posts you haven't had it scanned for codes or borrowed a fuel pressure tester to get an exact reading on fuel pressure. Both of these are obtainable from your local parts store.
If there is a code it will likely lead you to the source of your problem. JohnHL can tell you, his truck threw a code and he found a relay was bad. Also a pressure gauge can tell you if your even getting the correct amount of pressure at key on.

Just my two cents

 

thanks, and yes you may be right about the injector, although what else would cause my oil to smell like gas?
I do have a scanner, at first it threw the theft system code, so I erased it and it didnt come back. All theft lights are working normal.
I also dont see the point of buying a pressure tester if there is no pressure to test yet. Obviously will when it starts holding pressure.
I just tested the power going to the injectors, which were all good and the same. Tested the ground side with a test light going from battery positive, and no lights on any of them so they arent grounding open. Im in the process of getting a noid light next.
I really hope it is something easy I may have overlooked, cuz this is killin me.

 

So I got the noid light and they are pulsing fine, the weird thing is that when cranking it over with all injectirs unplugged, it tries to start more than with them plugged in. So now I am really confused.

 

Are you sure you don't have a PATS issue? Is the theft light on or flashing during cranking?