Weird starting problem

[KMc]

2000 Jeep Grand Cherokee 4.0L L6

First time you turn the key to start it, it never starts no matter how long you crank it or give it throttle or whatever. But, let off the key even for a second and try again and it will fire right up without a moment's hesitation.

It does this 100% of the time now.

Thoughts?

 

[chucky2]

My Ranger started doing this (but otherwise running fine and getting normal mpg) and it turned out to be the fuel pump.

Chuck

 

[MiataNC]

Probably a fuel pump/pressure problem as already mentioned.

Some amount of pressure is supposed to be maintained when the car is shut off. A bad regulator or pump will allow the system to bleed down while sitting.

Pumps are not active during cranking on many vehicles

If pressure bleeds out after the vehicle sits for a while, you will have to cycle a couple of times to get enough pressure to start.

 

[KMc]

Hmmm, that does makes some sense. I'm also wondering if it might be the fuel filter, or maybe some combination of the filter and the pump. This is a pretty high mileage vehicle and I don't know its service history, so I'll likely try the filter first (easier, cheaper) and see what happens.

 

[steppinthrax]

Do one test the next time you start it up leave the key in the on position for a couple of seconds and it should prime the pump or at least let the pump run longer to establish pressure. Then start it....

 

[Demon-Xanth]

Fuel pump or leak.

It'll pump for three seconds without the engine running. If it doesn't develop the pressure needed for the injectors they won't squirt. A second chance gives it more of a chance to develop the pressure.

 

[bruceb]

It sounds to me like the fuel pressure regulator
is bad. It is located on the end of fuel rail where
the injectors are mounted. That regulator has a
rubber diapraham insiide connected to a vacuum
source. That rubber piece goes bad from time to time.

 

[KMc]

Originally posted by: steppinthrax
Do one test the next time you start it up leave the key in the on position for a couple of seconds and it should prime the pump or at least let the pump run longer to establish pressure. Then start it....

Ok, this worked. So it looks like I have a leak back or pressure bleed situation. Guess I will check the regulator and bleed valve and if those aren't it, I guess it's new fuel pump time.