rhyzin

iTrader: (1)

HOW TO: '96 Eclipse GSX Fuel Pump Swap


(GSX Pump on the right)

What you'll need:

phillips screwdriver
flathead screwdriver or a knife
8mm open end wrench
Your gas tank to about 1/4 full or less. Mine was empty

---Step 1 (Getting the rear seat off):



Near the middle of each outer seat, you can feel around for where the rear seats attach to the car. Near where they are connected, just yank them out. The seats are clipped in and seem to be sturdy enough to not need to be so gentle.

---Step 2 (Getting the tank cover off):



Use the phillips screwdriver to take out the 4 screws holding the black access panel to the fuel pump.

---Step 3 (Bleeding the system):



Remove the wiring harness to the fuel pump. There is a tab opposite to where the wires enter. Push it while pulling the harness out. With the wiring harness disconnected, start the car and let it die. I only did it once. Take off your gas cap.

---Step 4 (Disconnecting the lines):



The fuel line to the rail is the one with the black harness. The hose with the clamp is the return line. Place a rag under both lines. First take out the line with the black harness. When you move it to the side, you now have room to move the clamp off the return hose and room to tug at it a bit. When tugging at the return line, you can push into it a little before pulling it. This kind of breaks a seal from when it was being clamped. Be careful though because this is all still just plastic.

Step 5 (Taking out the pump):



Remove the outside nuts with the 8mm open end wrench. You kind of have to get at the inside nuts at an angle.
You have to be careful as you might strip the nuts getting at them at an angle. The nuts are actually not torqued down very hard at all.

*Take note as to how much they were torqued down.



You should now just unplug the gray wiring harness from the pump. Push down on the small square while pulling out with your fingernail. Well thats how i did it. Also remove the black wire that clips onto the side of the assembly.

Twist the pump out as you pull on it. It should come out with a few twists and tugs. The only thing on the pump output shaft is a plastic spacer. I didn't use it. A wiring harness should still be attached. Push down on the tab of the wiring harness and pull it out.


(pic taken from vfaq.com)

I'm not sure but i took this step because of the clearance problem of the tank. The fuel filter from the lancer pump should be taken off and put on the GSX pump. Use the flathead or a knife to take off the circle metal clamp thingy. Keep at least one of them intact so you can put it on the new pump.

So with the wiring harness and fuel filter from the lancer brought over to the GSX pump, connect it all into the fuel pump assembly. take the bottom rubber piece from the lancer assembly and use it instead of the thicker GSX piece. Drop the whole assembly back into the tank.

* The assembly is going to stick out a little as if it doesn't fit. Fuggedaboutit! When tightening the nuts back on, it will seal. Since there is no spacer on the outlet shaft of the fuel pump and the bottom rubber piece is in fact rubber, it all squishes down and fits.

Step 6 (Put it all back together):

Installation is the reverse of removal. Note that one of the bolts on the tank has a red mark, as well as the metal plate that holds the fuel pump assembly down. The plate and plastic fuel pump assembly only go in one way so line up the red marks. Make sure you don't torque down those nuts hard as you may strip the threads or the nuts themselves. Probably a weak 5-6 lb's of torque(I don't know exactly). Really weak, but enough for a good seal.

Before putting the black access panel back, take a ride around the block that maybe involves swishing the gas in the tank. When you get back, check for leaks. If no leaks, no worries. Enjoy.

Nero

iTrader: (3)

nice how to bro... this looks like a damn fine project to get started on... can u feel alot of hp increse?

rhyzin

iTrader: (1)

well not really. i actually feel a *tiny* bit of bogging down, but i also have an adjustable fuel pressure regulator as well as an apexi safc at my disposal. i definately feel that there is enough fuel throughout the rpm band as some people (as well as myself) have felt a little starvation at high rpm.

it may be a different story tomorrow as the ecu might get used to the fuel pressure increase as well the fact as i haven't driven the car by myself since the install. i drove people around afterwards because i knew i wouldn't drive so hard with people in the car and that i can give the ecu time to get used to the change. the a/f ratio is very rich right now. tomorrow the restrictor plate comes off and more *rough* tuning as well as a header install.

liquidlancer

iTrader: (15)

so wait you have nothing on the bottom of the fuel pump to hold it to the rest of the housing?

Mitsiman

Some information for everyone to know - Mitsubishi runs the same fuel pump in 90% of its injected cars now. which is very good news for 4cyl people.

The same fuel pump in your lancer is the same as in our 6cyl 3.5 V6 magna / diamenta. We know for a fact that the stock fuel pump is good for 210hp at the front wheels on our V6 vehicle so what I am saying is unless you aer producing over 200hp at the front wheels there is nothing to be gained by replacing your fuel pump with a larger unit.

David Thomas
www.rpw.com.au

eslai

Hmm. Odd hack. Did you guys really need the extra fuel pressure? Did you try hard-wiring your stock pump to the battery first to see if that fixed the problem?

I can't imagine that the car really has a problem with fuel when just using basic bolt-on upgrades.

You'll need an OBD-2 datalogger to figure out the S-AFC low-throttle settings. That'll keep your fuel trims in check.

And that spacer might have been there for a reason. Just want to make sure you've really thought this mod over. Playing with your fuel system is never something to be taken lightly.

Oh, by the way, this should really be called a "2G 4G63 Fuel Pump Swap." The GSX and GS-T use the same fuel pump.

bahamut

There are two reasons why few mirages have done this mod . . . don't know if it was the same reasoning for rhyzin (can't speak for him): 1) Future mods & 2) a cheap replacement in lieu of getting a FPR.

We know mitsu designed our cars (mirages) conservatively and does a decent job of fueling the car at low and mid level rpm. However, it suffers from the lack any serious grunt at WOT.

Stock wise, the LS will drop power immediately after 5.2K rpm due to fuel and air restriction.

W/ intake and header, I managed to pull power up to 6.2K rpm, but it started to lack grunt from the lack of fuel.

W/ the GSX FP, I immediately felt enough fuel at WOT, but now I had run into the opposite problem. The FP is trying to over suppy the injectors.

Later, I had bigger injectors, bigger MAF and AFC w/ everything tuned properly. I started out with 24 average MPG stock in the city, and it would drop to a paltry 18 or 20 MPG during berserk driving. In the end, I had an average of 28-32 whether conservative or berserk driving in the city.

Other info. At idle, it runs like a regular FP (won't run rich, unless hacking or putting a bigger MAF). AT WOT, it fuels the car so effortlessly. AFC is needed to control WOT fueling.



Ah, the power wire mod from VFAQ. Most people won't put the effort to do it like hooking a bigger stereo system. You lancer guys had it easy a bit . . . we had to drop the stupid tank to even reach the dang FP.

Also, it's just using the name GSX because more people recognize the tag name than GS-T. No offense.

rhyzin

iTrader: (1)

i kinda replaced it for both reasons. i got an fpr but it didn't do much to raise the lean/conservative stock settings. when i had no fuel mods, it would seem that stock settings would be .84-.86v @ WOT and 0-.68v @ cruising. from what i've read, the consensus seemed to be that it should be .92v @ WOT and a cruising peak @ .8X-.9Xv. with the GSX pump, i now have those "safe" settings. i tried using the fpr and SAFC together before the FP upgrade, but i still couldn't get richer readings from my o2 sensor.

so far, no problems with it. the lack of the spacer hasn't caused any problems what-so-ever. if you guys are waiting for something to break, no luck yet.

with the MAF hack, the LO settings didn't change much from the when i had the old pump. it reduced my settings by 3% across the board. but my HI settings changed dramatically. i now have -22% at 1k and +6% at 7k. i think it's because of the header but i'm rich(.96-.98v) until 3k and comes down to .92v from there on. the curve is steep until 4.5k and then plateaus. before with the old pump, the HI settings mimic the LO settings, only at maybe 10% less across the board. it's a bit of a difference.

it would be helpful if somebody would check their o2 readings on a stock system so i know if i'm retarded (stock o2 voltage is as i read them) or if my car is just not working right. all of this post is off the top of my head as i'm in PA on vacation without my car.

eslai

Well, remember this isn't a turbocharged car or even all that high-compression. You don't need to run it that rich. .86-.89 would be totally reasonable, I'd think. Not that a narrowband sensor really tells you what's going on. Anyone ever get a wideband on these cars? I haven't been following along, unfortunately.

HobieKopek

iTrader: (8)

There was a wideband on mine for a bit and I'm going to eventually get one when I have money again (turbo and other expenses have crippled fundage for right now), but I'm sure someone will beat me to it in the meantime.

EDIT: And I'm running a Walbro 2g GS-T (they made the distinction so I'm makin' it too) fuel pump for the record.