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Unread 11-12-2013, 02:55 PM   #1
aleh17
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Fuel pump question, middle of 2.5 to 4.0 swap

Hey guys! So I'm in the middle of a 2.5 to 4.0 swap, I got the 4.0 out of a rolled Cherokee 98 and I have a fuel pump question.

Problem is my YJ is a 1990, so I guess I have the small fuel tank right? but the fuel pumps I find for it are for the 4.2 or 2.5 for my tank size. So in order to run the 4.0 and get the correct pump will I have to swap the fuel tank?

Thanks in advance!

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Unread 11-12-2013, 02:59 PM   #2
SeanB95YJ
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I believe so.... unless you can rig a newer (4.0) pump to your current sending unit

on the plus side - you'll soon have a 20 gal tank
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[FONT="Comic Sans MS"][COLOR="Blue"]Sean B. - Schenectady, NY - 95 YJ, 350/700r4/NP241, JB Shorty SYE, 8.8 rear, 2" BDS, 1" homebrew shackles, Daystar 1" BL, TJ flares, 35x12.50 General Grabber AT2 on 15x10 Bart D-Truckers, Polyshield polycarbonate windshield, HD over/under crossover steering
[/COLOR] [COLOR="Red"]swap/build thread: [url]http://www.jeepforum.com/forum/f22/after-almost-4-years-finally-my-own-build-swap-thread-1542284/[/url][/COLOR][/FONT]
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Unread 11-12-2013, 04:05 PM   #3
Randonexplosion
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Is your tank metal or poly? I think that is the deciding factor.
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Unread 11-12-2013, 07:48 PM   #4
owenb95
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You could always put in a rail pump and regulator. That's what I had to do with my 4.2 to 4.0 swap. I have been using a high flow inline racing pump and a regulator from Summit racing, been working great since I installed it.
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Unread 11-13-2013, 07:07 AM   #5
aleh17
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Thanks for the replies, my tank is metal one.

Quote:
Originally Posted by owenb95 View Post
You could always put in a rail pump and regulator. That's what I had to do with my 4.2 to 4.0 swap. I have been using a high flow inline racing pump and a regulator from Summit racing, been working great since I installed it.
thats a very interesting option, would you mind to elaborate? Do you use something like this? http://www.summitracing.com/parts/sum-g3136-2/overview/
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Unread 11-13-2013, 07:16 AM   #6
owenb95
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Yes you would use something like that. You would need a regulator that goes up to 60 psi because the 4.0 runs at 49psi. You would need a gauge like this,
http://www.summitracing.com/parts/sum-800160/overview/
To dial in the regulator to the right pressure.
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Unread 11-13-2013, 07:25 AM   #7
owenb95
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I used this regulator exactly,

http://www.summitracing.com/parts/pfs-10686/overview/

The only cons about it are the size of the threads are huge. After months of dealing with leaks because of all the reducer couplings i needed to step down to my hardened line i decided to just use barbed fittings on the regulator and pump and just run rubber fuel injection hose. It was simpler, cheaper, and no leaks!
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Unread 11-13-2013, 07:57 AM   #8
Que89YJ
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The 2.5L tbi fuel pump should put out more than enough pressure to supply the OBD2 cherokee 4.0. So you dont need to buy a new pump just the regulator. If you happen to find a poly tank from a 91-95 YJ I would use it. The extra 5 gallons is nice!
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Unread 11-13-2013, 08:09 AM   #9
SeanB95YJ
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Hey Que... I thought the TBI systems run PSI somewhere in the teens to low 20s, where the MPFI (4.0) is more in the 30s-low 40s range?

or is the 2.5 TBI pump just regulated way down to accommodate the TBI requirements?
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[FONT="Comic Sans MS"][COLOR="Blue"]Sean B. - Schenectady, NY - 95 YJ, 350/700r4/NP241, JB Shorty SYE, 8.8 rear, 2" BDS, 1" homebrew shackles, Daystar 1" BL, TJ flares, 35x12.50 General Grabber AT2 on 15x10 Bart D-Truckers, Polyshield polycarbonate windshield, HD over/under crossover steering
[/COLOR] [COLOR="Red"]swap/build thread: [url]http://www.jeepforum.com/forum/f22/after-almost-4-years-finally-my-own-build-swap-thread-1542284/[/url][/COLOR][/FONT]
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Unread 11-13-2013, 08:15 AM   #10
Que89YJ
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It does but it is regulated down at the rail. The pump still cranks out at least 50 psi on both so no problem using the pump from a TBI setup. You just have to deal with the pressure like Owen said because the OBD2 has the regulator in the tank.
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Unread 11-14-2013, 02:02 PM   #11
aleh17
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Good stuff guys, thanks a lot for the info, I just ordered exactly what owenb95 told, I will be re-using my fuel pump since you guys are saying it works, but just for future reference, if I want to replace the pump can I used the ones made for the 20 gallon thanks or is it different?
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Unread 11-14-2013, 02:23 PM   #12
Que89YJ
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Its different. i would still keep my eyes open for a poly tank.
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