Fuel Pump Troubleshooting

Been having intermittent (starting only) problems for a while on 2002 4.7, 133K one owner mile truck. No codes ever and runs great when running. It will start eventually but don't like the sound of an engine half starting being starved of fuel. New fuel filter installed already. No damaged fuel lines or leaks anywhere, also zero external fuel smells. Truck runs great when started.

This is the setup I finally got around to for checking fuel pump.

I was able to buy the correct banjo bolt and adaptor to hook a pressure gauge up to the fuel rail where the fuel diffuser lives. When I apply 12 volts from positive battery terminal for the low and high speed terminals at fuel pump relay sockets, I get 38 & 42 psi fuel pressure when pump energized.

When I remove voltage and pump isn't running the pressure quickly drops back to ZERO. Fuel rail will not hold fuel pressure when pump not energized, so my only thought is it needs a new fuel pump because internal check valve has failed if they have one?

Don't think fuel pressure regulator plays any part in this scenario when truck engine isn't running since it's vacuum operated. But I'm not sure? Was going to slave one in but don't want to waste $$ on unnecessary parts.

From what I've read here and other sites is the fuel pump will only start with key in crank position. Anyone on here rewired to possibly energize fuel pump with key to on position? That's normal setup as far as I'm concerned.

Any input or thoughts would be appreciated. THANKS

 

If the return hose is in good condition, you can clamp it shut, right as you shut the truck off, to see if it's leaking past the fpr.

 

https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

Full service manual for your year truck is linked in here. May be other troubleshooting advice in that section of FSM.

 

You do yourself and others a disservice by starting new related threads on this subject.

initial thread…. https://www.tundras.com/threads/fuel-pump-troubleshooting.160420/

followup thread….https://www.tundras.com/threads/fuel-pump-check-valve.159209/

 

dude, did you READ the link you sent him? it tells him nothing. It another tread asking a question with no responses.

 

Yeah, that's what Bubba is getting at, ,maybe you missed what he's saying?

OP is posting multiple threads without giving anyone time to respond. Usually when people do that, they get really weird responses, duplicate info, and it creates general confusion because there's no linear path for people to follow when others are trying to help out.

We had to deal with that a LOT recently with one of our other members with a 2007 Sequoia. We kept throwing out suggestions, only to get, "Oh, that was in my other troubleshooting thread, but not the 2nd one, the 3rd one..." then anyone helping had to go back and find that thread.

@BubbaW is simply telling @cadillacjoe - "be patient" and "stop creating totally separate threads for the same general problem".

 

The problem is they are all the same OP as this thread.

 

Hell, one is even the same thread

 

Here's the missing one.

https://www.tundras.com/threads/intermittent-starting-issue.157986

 

Yup. Guess I interpreted that differently. My bad

 

Hell and it ain’t even Monday
We be slow pokes in 1st Gen and ain’t as swooft as the Turd Gen pukes, I mean pokes.

 

Sorry my bad. I was impatient waiting for a reply but feel certain it's a fuel issue and was trying to stay away from rabbit hole replies. I guess I'm used to my old Caddy never breaking down.

So to keep in good graces of the 1st gen gurus, should I delete this 2nd thread to avoid confusion?