Why would a 1999 Chevy Tahoe 5.8 suddenly crank but not start only one hour after starting and running absolutely fine?

Answer 1

First, check to verify that it IS the fuel. Try a little starting fluid in the air intake to see if it will start briefly while an assistant tries to start the engine. Only use a couple seconds of starting fluid and see what it does.

If it DOES start briefly, it could be the pump, a relay, a connector or even "something else". After you've isolated the problem to the fuel delivery system, check the wiring to verify that you are getting power to the fuel pump when the key is turned on. Recognize that most injected systems only turn on the fuel pump for a couple seconds if the engine doesn't start, so you'll have to connect a meter and watch it closley when the key is turned on.

After that, let's see what happens.

Had same problem on 01 Tahoe. Finally after worrying with lots of "tune up" things, fuel filter, etc, happened upon a mechanic that said,"Sounds like the fuel pressure regulator has a ruptured diaphragm." Went to dealer and got one, put it in (simple fix on driver's side of engine. It has a small plastic vacuum hose going to it and is held on by a spring clamp) and haven't had another problem. Be sure to remove the small o-ring in the hole. If it stays there you won't be able to put the new regulator in. Best to take out the o-ring, put it on the new regulator and then put it back in the hole.

If the diaphragm is rupture it lets raw fuel continue to go into the intake manifold and basically "floods" the engine. That's why it starts good cold or after it sits a couple of hours, but if it sits 15 minutes it is hard to start.