Fuel rail question

I need to replace my fuel rail on my 01 because the cups where the injectors go are corroded and tear the injector o rings up causing them to leak. I've got a spare rail off a 99 motor but my 01 has this damper thing on the rail (upper rail in the photo) that isn't there on the older one. What does this do? Do I need it and will my jeep explode in a fiery death if I put this other one on it? Thanks.

Nobody?

I noticed the 99 im working on has that too. Is that a regulator or something?

I have no idea what that thing is either lol.

Odd. My 01 has it but the 99 motor doesn't.

Id say use it and see what happens.

IF you dont have o ring leaks you should be ok? If its needed it might just run like crap.

Runs good. Better than before maybe.

It'll work just fine. It is a damper. When the fuel pump first applies pressure to the fuel rail, it has a tendency for the fuel rail to make a pop or a bang or some odd noise. The damper helps eliminate the noise.

There was a variety of types used, some large, some small. Some were even chrome plated.

I wonder if that caused by the higher pressure fuel systems in later years.

it started showing up on 4.0 rails somewhere in the early 00's, i think. i've seen a couple develop leaks there at the damper diaphragm. you'll never notice any difference without it. and it's one less thing to go wrong on a trip.

Ecomike said:

I wonder if that caused by the higher pressure fuel systems in later years.

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Correct

Hellbent said:

it started showing up on 4.0 rails somewhere in the early 00's, i think. i've seen a couple develop leaks there at the damper diaphragm. you'll never notice any difference without it. and it's one less thing to go wrong on a trip.

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ZJs started in '99 and some '99 late model year XJs had them.

rstarch345 said:

ZJs started in '99 and some '99 late model year XJs had them.

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If they started in '99 on the grand Cherokees it would be WJs not ZJs

My 99.5 (April '99) has a damper. I got a 2000 rail off ebay and cleaned it up and am using it on my '99. The 99 damper I had is different from the 00, 99 looks like the upper one in the photo.

From what I've read, the damper works constantly to dampen out the pulses from the injectors opening and closing.

The damper is there to control pressure surges because it is a non return system. Has nothing to do with sound.

Talyn, how come the 98's dont have the dampers? They are returnless as well.

I know you are right about this but I am curious as why they added it on later model years.

stockli said:

Talyn, how come the 98's dont have the dampers? They are returnless as well.

I know you are right about this but I am curious as why they added it on later model years.

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They usually learn from mistakes in prior years, so 98 may be the year they had problems, but the fix was not standard until 99?

96 and 97 were also no return, no damper years. I can only guess that it's either a NVH or emissions related change. My donor intake came from a late 99, which had the newer manifold and injectors, along with the damper on the rail. Same fuel pump, same lines, same motor, (same head?)... if nothing else changed, why was a change needed?

In '99 they also went to different injectors. Perhaps that has some bearing.

Perhaps there is some weird circumstance that caused an issue with fuel control.

Talyn said:

In '99 they also went to different injectors. Perhaps that has some bearing.

Perhaps there is some weird circumstance that caused an issue with fuel control.

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The injectors on both of these engines are identical but one had the damper and one didn't.

According to the 97-99, 2000, and 2001 parts catalogs:

Part number 4854102 fuel rail was introduced in 1999 but was changed to part number 5014496AA for 00 and 01.

The 99 rail had the replaceable damper, part number 4591520AA, and the 00 and 01 had a small non-replaceable damper. I got the 99 damper part number directly off the damper (on my bench). The damper part numbers do not show up in the parts catalog.

Rail 4854102 only lasted one model year (99). I think the replaceable damper proved to be a flame thrower so they got rid of it in favor of the non-replaceable damper...who knows, it may have been just cheaper to produce the rail with the non-replaceable damper.

Part number 4854181 injectors were introduced in model year 1999, and carried over to later years. This part number was also used in many Chrysler vehicles. I don't think rail/damper design was based on injector function, in that the rail/damper design changed while the injectors remained the same from 99 through 01.

Edit: Forgot to mention that the 97/98 rails, part number 53030699, were used with injector part number 53030778. The lack of a damper on these rails may have to do with the type of injector used. I would suggest the use of a 00/01 rail, part number 5014496AA, with part number 4854181 (or their equivalent upgrades) injectors.