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99 fuel rail to 89 fuel setup

Weasel

Weasel

NAXJA Forum User
NAXJA Member
Location
Billings MT/Rapid City SD
I'm in the process of swapping a 99 4.0 into my 89 XJ. I have it in and most of the wiring done but am running into a issue with the fuel rail. The intake I have is not the newest curved rail design but the one before it.

The 89 had the fuel regulator on the front of the rail and a return on the rear. Well the rail I have only has the fuel in on the front with no return line.

So how do I convert this over? The fuel rail from my 89 won't fit the intake. Can I just run an aftermarket fuel regulator and cap the return line?
 
You'll need to modify the Renix rail to fit, or see if a 91-95 rail will fit on the newer intake. I've heard some year rails will interchange, and I know that the 91-95 rail works with the Renix fuel pump and that the Renix injectors fit in it. The fuel lines are in different places, but that can be fixed by using some extra rubber fuel line. I completely did away with the quick release connectors when I hooked up the lines. I have a 93 rail, intake, and complete engine working fine on Renix, with the Renix injectors and fuel pump.
 
hmm...

I thought there were three different styles on intakes; Renix, HO, and 99+? The intake i have is the HO style and the fuel rail came with it. Does the regulator from a 91-95 have the return line to the tank? If so it's seems I would just need one of those or a regulator with a return line and run the lines.
 
91-95 rail has a return line, it's just in a different place so you need to change the lines a little bit.
 
Just wondering ..do the injectors line up and the bolts don't or are the injectors stagered wrong ? Beacouse I was able to fit my 89 fule rail on the newer curved manifold but the bolt didn't line up ,so I made tabs so that I could bolt it down . Good luck either way.
 
The 91-95's have the return but the lines won't work. The "newer" fuel rail has the return at the front of they rail (closest to radiator). The Renix fuel rail has it in the rear of the fuel rail (closest to firewall) I just swapped in a stroker with the newer fuel rail and had to extend the return line with a piece of SS brake line and some fuel injection hose. I flared the ends of the pieces of brake line for the splices but I don't think you would have too. Also your TPS is different on the Renix motor and won't bolt up the newer Throttle bodys. There are fixes to that, which you may have found already, but one option is Hesco has an adaptor to make it work. They are proud of their stuff but it's saved me wiring so it was worth the 130 bucks.


Parakeet
 
91-96 have the correct rail for you, as others have stated. Only difference is that both the return and send lines are right next to each other on the front. As said you can modify your original to fit though.

Lucky you have a 4.0, try finding thsi stuff for the 2.5!

good luck!
 
ok here is a pic...

driverside.jpg


You can see the inlet or whatever it is right above the power steering cap. As far as I can tell there are no others inlets/outlets. The ports line up with the injectors and bolts down fine.

The old rail doesn't line up with the bolts and the old intake has flat spots for the rail while the new intake has them slanted.

As for the TPS I got one from a 98-97 and it seems like it bolts up ok.

Painless harness is what I'm using so minimal factory wiring.
 
Mr_Random said:
91-96 have the correct rail for you, as others have stated. Only difference is that both the return and send lines are right next to each other on the front. As said you can modify your original to fit though.

Lucky you have a 4.0, try finding thsi stuff for the 2.5!

good luck!
Click to expand...

cool, good to know. Looks like I have the wrong rail still. Thanks.
 
You are good if you are going the painless route.

I think the cut off was 96 that they eliminated the return line. Some 96's will have the return line and some wont from my experience. I bought what was told to be a 94 for the top end but after checking some casting numbers on the head I found out it was a 96-98 motor but still had the return line on the fuel rail.

I would hit up the JY to see if you can find a fuel rail with the returns and extend your lines. But I have to wonder about capping the return line off at the pump and running it that way. I'm sure somebody will chime in to say yes or no on that. The 96+ fuel rail as I understand it will bolt up either HO or 99+ intake
 
There is a local guy that has XJ stuff, so I will hit him up and see if he has the other style rail.

Painless kit rocks, I have 90% of it installed already.

When the switched to the no return line, they also moved the regulator down by the fuel pump from what I've found.

I could get a regulator from Jegs but that's another 130-200 buck i don't have to spend.
 
I have an 03 grand cherokee in my 88 renix xj-very simple
1-see if you can get the fuel line/hose up to the 99 rail from a junk yard
2-take the original supply line up to the metal line and couple it to that
line with a 3/8 compresion fitting-nay sayers---"it does not leak!"
3-get a fuel filter for an 03 grand cherokee 4.0-the filter assembly has
the regulator built into it-you will have to adapt the lines from 3/8
to 5/16 you can use brass fittings with fuel injection hose and clamps
4-one line goes to the rail and the other 2 go to the tank-return and
supply
thats it- it is simple and the benefit is cool fuel to the tank and cool fuel up to the engine-the whole idea behind the returnless design is no heated fuel back to the tank to reduce fuel tank pressure - and as a bonus it helps with engine power-cool fuel into the injector-every LITTLE bit helps the 4.0
If you need pictures i will try to post some to see what i am talking about
hope this helped you
 
saweet! that will work as well, wondered if something like this was possible.

I will check out the fuel filter. I think I can figure out the hoses.
 
what the hell are you talking about? the return line IS the reason the fuel returns to the tank warm...............fuel constantly flowing from the fuel in the tank is cool-go ahead spill some fuel on your hand in 90 * temps and tell me it's warm:gee:
Well anyways not to sound so sarcastic but it seems like your saying you need warm fuel????
and why did most car makers go returnless???????????
think about that for a minute................
 
winterbeater said:
Not having the return line to keep the fuel in the rail cool can lead to the heat soak issues. Hard hot restart, etc.
Click to expand...

Weasel said:
Newer ones run a higher pressure so should not be an issue.
Click to expand...

What's that got to do with the price of tea in China? Running at a higher pressure with injectors designed for it won't make it any easier to start when it's heat soaked than one that's running a lower pressure.
 
Weasel said:
saw your radiator system is pressurized, same reason vapor lock doesn't normally happen with FI and does with carbed systems.
Click to expand...

You saw who's radiator system is pressurized, mine? You don't know WTF your talking about. Just because mine is an 88 doesn't mean that I haven't changed it to the newer style. Stop making assumptions and coming to false conclusions. And that's not the reason that vapor lock does not occur on FI like it does on carb models, it has to do with the location of the pump being lower and at the starting point instead of at a point higher than the fuel source like a carb model. I know thats an over simplification but you get the idea. Stop talking out of your rear end and only speak when you know WTF your talking about.
 
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