Ok so I did the test... I have the money to work on this thing so I need the quickest reply as possible to know what to change.

I hooked up the pressure gauge and when the key got turned to the "on" position the pressure would jump to 40psi but only for about a second, maybe two and then go right back to 0. That's it.... I tried starting it once and it would go up to 40psi and stay there until you stopped turning the key. So I'm guessing fuel pump... anyone?! Would like to get this fixed TODAY.

 

Weak fuel pump

 

So replace fuel pump? Not a fpr or something else?

 

it most likely sounds like a weak pump if it was the fpr it would be 55 to 60 psi and you would have a leak in 10 mins

also when you change the pump you should change the fuel filter also

 

Update... I changed out the fuel filter today hoping this would cure the problem of weak pressure. I was praying that I just had a clogged filter and it was keeping the pump from being abld to deliver fuel. Well when I took off the old filter it had A LOT of rust inside of it, it freaked me out! Now I'm wondering if I just have a dirty/rusty tank and the fuel pump just can't pump properly due to the in tank screen/filter being clogged. Could it be that the pump itself is still good but something it obstructing it from doing its job in the tank?? I'm wondering if before purchasing a new $300+ fuel pump if I should try to clean out the inside of the tank and clean off the pump and screen? Then try it again and see if I get the correct psi in order to run the truck... let me know what y'all think. Thanks a lot.

*edit* oh and no the new fuel filter did not fix the pressure issue, still jumps to 45 real quick and then nothing and no start. Not even a hesitation!

 

I think you meant to say that you changed the fuel filter in the post above...

Have you done EVERY step detailed in the tech article? I ask because it would lead you to the cause of the problem instead of guessing... Don't jump to conclusions as gio has already done. It can be an expensive mistake for you.

A failed FPR can DEFINITELY cause the conditions you are experiencing although it is not as likely as a failed pump for the '96+ trucks. Thorough testing by eliminating the engine & return system from the fuel system (testing at the filter with the appropriate adapters detailed in the tech article ) will tell the tale without guessing.

If you are going to open up the tank, replace the pump. Even if the filter sock is clogged, the likelihood of pump damage is very high.

 

Another question... if the fuel pump is only pushin out 45 psi than wouldn't that be enough for it to ATLEAST putter a little or something? Or is that valve (where you check the pressure) before the FPR and the 40psi just isn't even enough to get past the diaphragm or something? I'm just so confused on how this works... and I'm sorry, I truly dont understand you sticky on the fuel system diagnostic. Can you please explain to me why the 40psi will not even remotely start the vehicle! It just doesn't make sense to me unless its just not enough pressure to get through the FPR. If thr FPR is before the valve u check the pressure than why couldn't it be that?

Anyone?

 

Please be patient! No one gets paid to sit here and wait for you to ask a question. A reasonable time frame to wait before bumping a post is 24 hours, regardless of your urgency as stated in the rules of the forum.

An no, it won't just putter along. Given the setup of the fuel system, if the pressure is too low, no fuel will get to the cylinders, not even a little. This is explained in detail in other posts... Without going into great detail because it's covered elsewhere, the poppet nozzles need ~52psi to even open and >55psi to spray properly. The FPR is after all of the injectors and is what maintains the fuel pressure to the injectors. But if the pump isn't providing the proper pressure to begin with, it's kinda hard to maintain it at a higher pressure. At this point, you haven't figured out whether it's an FPR issue or a pump issue.

I have given you the next step in the diagnosis already... Do the tests I have instructed you to do at the fuel filter and that will show you whether it is an FPR issue or a pump issue. Until then, I'm out. The details are in the fuel system diagnosis thread. Print it if you have to (including the tables showing the steps).

 

Swartlkk: seriously, you have NO IDEA how greatful I am for all of your help! And now even more so for the great diagnostic you wrote that I once called "jibberish" haha. Last night when I read it, it was just that! But now today, between speaking with you on here, getting hands on with the fuel system and much reading, I fully understand your diagram. (If you wrote the diagram yourself than kudos my friend, good stuff!) I apologize if I'm bugging you and I also apologize about bumping the post to early, don't want to ruin anyones experience on this forum (because its a GREAT one) and I again... TRULY appreciate your patience with me and ALL of your help. The final question I have is relitivly simple and I will be using you guide tomorrow, so it will run me right into what needs to be replaced. I just don't know what 2 of the definitions are for the names of the parts on your sticky. I don't know exactly what they're referring to...

First, what is the fuel pump flex pipe? Is this the hose that runs up and down inside of the tank, connected to the fuel pump?

Second... what is the shut off adaptor and fuel sender? Where are these located?

Thanks a lot! If u can just answer these last two things for me ill be able to follow your guide... later

 

ive been having same problem for a month-so i changed my fuel pump cause it was stalling on me and not starting back up-when gas in throttle body starts up then dies-after i changed the pump it ran for about 200 miles then started w the same problem-now it idles soo low it wants to die at lights-i think the injectors my be in need of professional cleaning,also the brale lights are wired through the fuel pump ive heard and can cause similar problems-hope u get back on the road and figure it out-but you might save a couple hundred buying a pump on amazon they are about 120!!