View Full Version : Do I need a new fuel pump if I'm switching to fuel injection?
01-07-2005, 04:24 AM
I'm swapping my original '87 2.5L (TBI)motor out of my Wrangler and replacing it with a '95 2.5L (fuel inj.) Can I keep my original fuel pump? Will it put out enough pressure for the new engine?
Thanks in advance.
01-07-2005, 04:50 AM
??? What's TBI, what's fuel injection?
Truthfully - the fuel pump in your 87 is over 15 years old if it is original. Replace it.
You may get more info on a "little Jeep" website.
[ January 07, 2005, 11:51 AM: Message edited by: brad_fsj10 ]
01-07-2005, 05:23 AM
You need to check the flow requirements of the EFI system your putting on. Most mechanical fuel pumps designed for a carbe'd application dont have enough pressure output to handle EFI. I think stock PSI is 3-5psi and If I remember right lots of EFI systems run at least 20psi.
01-07-2005, 07:00 AM
Most likely your TBI had an electic fuel pump that kept a constant 15psi. Your newer fuel injection may require a higher constant pressure even as high as 30psi if it's multi-port. Check out the specs, but you may need to upgrade.
01-07-2005, 07:15 AM
Yeah, and MFI also uses special fuel line designed for over 25psi. Yes, you will definitely need a new fuel pump, along with a new computer and wiring harness from the newer motor. Are you sure the '87 motor isn't MFI? I thought all the 2.5L motors in the wranglers had MFI like the 4.0L six. In that case, the '95 would be very similar.
If you're going to all this trouble, why not swap in the six???
Oh, and for reference, TBI means throttle body fuel injection. They would both be fuel injected motors, just of a different type. TBI is a low pressure system.
[ January 07, 2005, 02:16 PM: Message edited by: The Anti-Chrysler ]
01-07-2005, 07:47 AM
I have TBI in my Blazer and when I changed out the (fuel)filter I had just run it so the fuel pissed out from the fuel pump side until the presure dropped, so I'm guessing that you're stock fuel pump wouldn't work with the 3-5PSI.
The stock pumps are easy to replace though.
01-07-2005, 10:55 AM
Originally posted by The Anti-Chrysler:
Are you sure the '87 motor isn't MFI? I thought all the 2.5L motors in the wranglers had MFI like the 4.0L six.Nope, wranglers from 87-90 had throttle body injected 2.5's. Then in 91 when they started putting in 4.0's they switched the 2.5's to multi port that the 4.0's use.
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