2000 TJ 4.0L fuel injectors

Matt, my guess is that your problem isn't from leaky injectors at all,
I'd bet big $$$ that it's a leaky anti-drainback valve which is located
on the fuel pump/regulator assembly. When it leaks, it allows the fuel
to drain down out of the injectors and fuel rail into the fuel tank,
causing longer starts while the fuel makes its way back up to the fuel
injectors. This of course also bleeds the pressure off down to zero.
From your symptoms, I'd give a 99.9999999% chance of this. This is
fairly common and I've yet to hear/read of any other reason for your
symptoms. While there have been rumors you can buy just the
anti-drainback valve, others say you have to buy the entire fuel pump
and fuel regulator assembly.

Matt Osborn wrote:
> I have 110,000 miles on my TJ and am losing what I assume to be fuel
> rail pressure when parked for a few hours. Before starting the
> engine, I leave the ignition in the on position for a few seconds
> before cranking the starter. The engine always starts promptly when I
> do this.
>
> Before running up the maintenance bills, cleaning the injectors,
> replacing o-rings, etc., I thought it might be better to simply
> replace the injectors.
>
> I guess what I'm asking is if fuel injectors 'wear out'. That is, how
> long will a set of injectors last?
>
>
> -- msosborn at msosborn dot com

--
Jerry Bransford
PP-ASEL N6TAY
See the Geezer Jeep at
http://members.cox.net/jerrypb/

Jerry, that's the first time anyone has mentioned that valve being a
seperate unit but it rings a bell. I've replaced several pumps in
different vehicles over the past few years (comes with kids doing
their own repairs - "Hey, Dad...") and it got me to thinking. Best I
can recall, every single one I replaced had that valve in the piece of
hose between the pump and the mount! I just looked and I have 3-4 of
them in a junk box - some even have the flow direction indicated.
Looks like a 50 cent part - wonder who sells them? It's just a ball
with a spring to seat it until pump pressure pushes it open. I
haven't had the opportunity (yet) to look at the newer pumps with the
integral regualtor so that may require a whole pump assy but dollars
to donuts you are onto something for the older ones with the external
regualtors.

With my luck all my pump problems so far have been total, undeniable
pump failures but this is a good thing to keep in mind.

On Fri, 2 Dec 2005 17:08:55 UTC Jerry Bransford >
wrote:

> Matt, my guess is that your problem isn't from leaky injectors at all,
> I'd bet big $$$ that it's a leaky anti-drainback valve which is located
> on the fuel pump/regulator assembly. When it leaks, it allows the fuel
> to drain down out of the injectors and fuel rail into the fuel tank,
> causing longer starts while the fuel makes its way back up to the fuel
> injectors. This of course also bleeds the pressure off down to zero.
> From your symptoms, I'd give a 99.9999999% chance of this. This is
> fairly common and I've yet to hear/read of any other reason for your
> symptoms. While there have been rumors you can buy just the
> anti-drainback valve, others say you have to buy the entire fuel pump
> and fuel regulator assembly.
>
> Matt Osborn wrote:
> > I have 110,000 miles on my TJ and am losing what I assume to be fuel
> > rail pressure when parked for a few hours. Before starting the
> > engine, I leave the ignition in the on position for a few seconds
> > before cranking the starter. The engine always starts promptly when I
> > do this.
> >
> > Before running up the maintenance bills, cleaning the injectors,
> > replacing o-rings, etc., I thought it might be better to simply
> > replace the injectors.
> >
> > I guess what I'm asking is if fuel injectors 'wear out'. That is, how
> > long will a set of injectors last?
> >
> >
> > -- msosborn at msosborn dot com
>


--
Will Honea

Will Honea did pass the time by typing:
> Jerry, that's the first time anyone has mentioned that valve being a
> seperate unit but it rings a bell. I've replaced several pumps in
> different vehicles over the past few years (comes with kids doing
> their own repairs - "Hey, Dad...") and it got me to thinking. Best I
> can recall, every single one I replaced had that valve in the piece of
> hose between the pump and the mount! I just looked and I have 3-4 of
> them in a junk box - some even have the flow direction indicated.
> Looks like a 50 cent part - wonder who sells them? It's just a ball
> with a spring to seat it until pump pressure pushes it open. I
> haven't had the opportunity (yet) to look at the newer pumps with the
> integral regualtor so that may require a whole pump assy but dollars
> to donuts you are onto something for the older ones with the external
> regualtors.

You can put an external check valve in the line between the fuel pump
and filter. It's loads cheaper than a new pump.

I'd check race and marine stores, but NAPA should have them.

--
DougW

You of course can always add an anti-drainback valve anywhere in the
feed line, which would be as good of a fix as replacing the OE
anti-drainback valve would be. As said already, I'd bet big $$$ your
problem is nothing more than a leaky antidrainback valve.

Jerry

Will Honea wrote:
> Jerry, that's the first time anyone has mentioned that valve being a
> seperate unit but it rings a bell. I've replaced several pumps in
> different vehicles over the past few years (comes with kids doing
> their own repairs - "Hey, Dad...") and it got me to thinking. Best I
> can recall, every single one I replaced had that valve in the piece of
> hose between the pump and the mount! I just looked and I have 3-4 of
> them in a junk box - some even have the flow direction indicated.
> Looks like a 50 cent part - wonder who sells them? It's just a ball
> with a spring to seat it until pump pressure pushes it open. I
> haven't had the opportunity (yet) to look at the newer pumps with the
> integral regualtor so that may require a whole pump assy but dollars
> to donuts you are onto something for the older ones with the external
> regualtors.
>
> With my luck all my pump problems so far have been total, undeniable
> pump failures but this is a good thing to keep in mind.
>
> On Fri, 2 Dec 2005 17:08:55 UTC Jerry Bransford >
> wrote:
>
>
>>Matt, my guess is that your problem isn't from leaky injectors at all,
>>I'd bet big $$$ that it's a leaky anti-drainback valve which is located
>>on the fuel pump/regulator assembly. When it leaks, it allows the fuel
>>to drain down out of the injectors and fuel rail into the fuel tank,
>>causing longer starts while the fuel makes its way back up to the fuel
>>injectors. This of course also bleeds the pressure off down to zero.
>> From your symptoms, I'd give a 99.9999999% chance of this. This is
>>fairly common and I've yet to hear/read of any other reason for your
>>symptoms. While there have been rumors you can buy just the
>>anti-drainback valve, others say you have to buy the entire fuel pump
>>and fuel regulator assembly.
>>
>>Matt Osborn wrote:
>>
>>>I have 110,000 miles on my TJ and am losing what I assume to be fuel
>>>rail pressure when parked for a few hours. Before starting the
>>>engine, I leave the ignition in the on position for a few seconds
>>>before cranking the starter. The engine always starts promptly when I
>>>do this.
>>>
>>>Before running up the maintenance bills, cleaning the injectors,
>>>replacing o-rings, etc., I thought it might be better to simply
>>>replace the injectors.
>>>
>>>I guess what I'm asking is if fuel injectors 'wear out'. That is, how
>>>long will a set of injectors last?
>>>
>>>
>>>-- msosborn at msosborn dot com
>>
>
>

--
Jerry Bransford
PP-ASEL N6TAY
See the Geezer Jeep at
http://members.cox.net/jerrypb/