Topic: 4 banger transplant. Need some tech advice/info

[Backroads]

New to the forum, just got into a 90YJ and decided here would be a good place to NOT hear people tell me to just do a 4.0 or 350 swap 

As I said, its a 90 yj, 5 speed, 231. Got it from a friend who hyrdolocked it, then as most jeeps do...it threw a rod a month or so later and did this...



so the hunt was on for a swap. Another buddy of mine just happened to have a 93 YJ tub sitting in his yard, with a good 2.5 sitting in it. The past few weeks I've pulled the old 2.5, and cleaned everything up. Got the donor 2.5 ready to be lifted out as soon as I can get back to work on it.

So it brings up a couple issues, I'm hoping someone can help me with....but before I say that I want to state this project is #1 priority is to get it back on the road and reliable...asap. I'm not really interested in or have time right now to get into a drawn out build (or I probably would have gone 4.0 or 350...)

I was planning to reuse the original trans, clutch and flywheel on the new engine (I know for a fact everything is good, and was driving a month ago) Will the 93 bolt up to the 90 trans with no problem? No spline differences or anything?

If I was going to convert to FI, do I need to swap out the dash harness to work with the FI engine harness or will that plug into the firewall at the fuse panel without modification? (I have both dash harness' but the donor has some stuff cut off 

What other issues am I going to have to deal with?!

Thanks for any help!

[Jeffy]

If the donor is complete you might as well grab everything off it and convert it to MPFI.  You will want to swap all of the engine harness and probably the dash harness as well.  Some things are different.  electrical speedo, no clock, etc...  Grab his gauges as well.  Grab his gas tank and fuel pump, grab his emissions, etc...

You can use your transmission if you want to.  It will bolt right up.  Basically swap everything till it runs.

Otherwise swap your intake on the donor and keep it TBI.

[Backroads]

Thats my hangup. The donor is about 85% there. No gauges, interior etc. Old rotten fuel lines and everything in the rear.

But good to know about the trans, at least I know I can get the engine in place, then figure out what to do with my wiring and emissions stuff.

[Jeffy]

Thats my hangup. The donor is about 85% there. No gauges, interior etc. Old rotten fuel lines and everything in the rear.

But good to know about the trans, at least I know I can get the engine in place, then figure out what to do with my wiring and emissions stuff.

The fuel lines should be hardlines from the firewall to the back tire.  Then it goes into the fuel filter and then a rubber line.  From the firewall it should be hard plastic.

For the gauges you could probably reuse your harness.  You would want to check the pin-outs so the right gauges get the right signal.  The clock on the last gauge was replaced with a 4WD indicator in the first slot and all the other gauges moved down.  Your speedo is manual and the PCM will need to see the speedometer signal to run properly.  Swapping the sender for a electronic one is simple.  For the main dash gauges you could go aftermarket.

Also if the tank is there you could do a 20 gallon conversion if it's not a 20 gallon to begin with.  If you have a 15 gallon tank in yours it will look tiny in comparison.  If you have a 20 gallon tank or want to keep your existing tank, you could add an inline fuel pump and mount it on one of the crossmembers.  This will pull through your old pump.

Overall, I think parts should be easy to come by as they are old and people don't really want them.

[Backroads]

Thanks a lot for all your help! I got the other engine home last night, so now I get to finally start putting things back together. I was looking into new mounts, but I see they offer (quadratec anyways, its about 30 mins from my house) 2 different mount kits for a 2.5 YJ. 87-90, and 91-95.

Being that I'm putting a 93 engine into a 90, which kit do I use? and whats the difference. They look identical in the pictures...

[Jeffy]

It probably doesn't matter as long as the engine is in the same place.  If you can snap some pics of your mounts and we'll be able to compare them with the new ones.

[Torch_Ind]

did you do block damage?  I blew the block and took out the came and front cover at the same time when my blew!!

[Backroads]

I'll have to get pics of the mounts....but they are all literally destroyed..

but ya, many holes in the block! more pics of the blow up


didnt see this one til I took off the PS pump!


and the last one, and actually with a shot of the mount on the 90 2.5

[Backroads]

Gonna bring this one back, The swap is now complete and after working out last weeks bugs (http://4bangerjp.com/forums/index.php/topic,9114.0.html)

Ive found I had a leaky tank, which I suspected was the fuel pump gasket...which it was NOT. Its the older 14.5 gal steel tank.

Now when i got the engine (93 era FI) I got the tank and pump as well. Its the larger 20gal plastic tank. It looks like it should bolt up no problem, has similar outputs on the fuel pump. Just a slightly different vent setup.

My question is, can I use this tank and pump on my TBI engine? (i left it TBI when I did the swap) Or is the pump not right or any issues there?

Also, the wires on the pump in he 20gal tank are cut, can I just splice my old plug into them?

[chardrc]

take a look at these:

http://www.jeepforum.com/forum/f12/tbi-vs-mpi-fuel-pump-compability-1080029/
http://www.jeepforum.com/forum/f12/metal-plastic-fuel-tank-swap-1088945/

if i remember correctly the gist of it is that tbi will work with the mpfi tank and pump but you have to make sure your fpr is still providing the injector with the correct pressure (may need adjustment)... (read the threads i was looking at doing the same thing end of the summer when my metal tank sprang a leak but i patched it as i had to start concentrating on school)

[sharpxmen]

like chadrc said, the pump should work but you need to adjust the pressure (or at least verify it). The downside is that you will move way more fuel than you need and will heat up the fuel as well - since you will be running lot less pressure the flow will increase substantially, will bleed off the return though but will have the downside i mentioned. One thing you might run into is the lack of adjustment at idle due to increase flow which might result in lack of pressure at top power, what i mean by that is that when you need minimal flow you will adjust the regulator too low due to backpressure thru the return orifice of the pressure regulator and when running at top power to not have enough spring weight on the regulator to keep the pressure you need since the flow thru the return will be less - you'll have to try and see if that's the case or not

[Backroads]

Thanks for the comments guys....I understand what your both saying, gonna give the links a look at take it from there.

I'm assuming there is no TBI style pump that fits the newer style tanks?

I'm not so much worried about the size of the tank, I just happen to have 2 spare plastic tanks that are of the 20gal flavor  I'll report back with my findings..

[Jeffy]

I haven't looked at the pumps but you might see if you can swap the fuel pumps.  Not the fuel pump assemblies but the pumps.  Otherwise you could omit the pump all together and run an external pump.

[chardrc]

I haven't looked at the pumps but you might see if you can swap the fuel pumps.  Not the fuel pump assemblies but the pumps. 

that wont work. the tbi pump is too big to fit the mpfi sender.. its covered in one of those links.

[Backroads]

Well after doing some digging I think I might just get another tank thats correct for my wrangler. I'm not overly concerned about the volume of the tank, would be nice but not absolutely necessary, especially if I can fill it and not have it leak all over the place 

I just dont know if I trust the high pressure pump in there, I wheel some remote places and would HATE to have some kind of technical issue I couldnt solve and be stuck somewhere!

I can always carry a spare gerry can of gas though!


So on that note whats the best deal any of you know on a poly 15gal tank for TBI era Yj?s I'm seeing around 120 or so..