tlrxj11

I have a 93 I just swapped my 4.0 motor for another motor out of a 94 wrangler. I got the motor from a guy that said it ran well in the wrangler before he pulled it and sold it to me. I got it in and everything is hooked up, I started it and it ran but sounds like it's either missing or the timing is off. I decided to drive it around the block and it was doing alright then killed over right before my driveway, then wouldn't hardly start without a shot of ether to get her going. Has anyone had this problem before and could help? If the motor ran good in the wrangler and the timing was good then why won't it now? Any help appreciated!

Battle

It could be a lot of things. A vacuum leak, fuel issue, the ECU is learning the new engine, bad spark, etc. I doubt it would be timing as these rarely get out of time besides top-end i.e. distributor/cap/rotor.

Also I hate to say it, but unless you saw it run great before your own eyes, it's just his word that says it was running great.

Do you have a Check Engine Light?

Ant.

If it started up with a shot of either,

I am wondering if you are haveing a fuel issue.. Have you checked fuel pressure at the rail? I would start there..

I have a 99 cherokee Sport 4.0/4x4, I need 49PSI at the rail to start my engine, I am not sure if it is the same in your jeep...

Ant...

tlrxj11

Check engine light is on, never been on before even with many issues with my old motor. I got it from an auto salvage place and they gave me a two year guarantee so I don't see why they would sell me it if it didn't run good. I'm just stumped unless I did something wrong when installing it

tlrxj11

I used the original intake manifold and injectors and fuel rail and whatnot of the wrangler motor, not off my Cherokees motor, idk if that makes a difference. Is a wranglers psi different than a Cherokees? Same motor and intake, I would think so, I'm no expert

Ant.

There is a number of things that it can be,
Do you have a good spark? If you have good spark I would think fuel is the problem..

Also if it ran with a shot of either that is pointing towards fuel issue as well..

Check fuel pressure,

If you do not have a gauge you can get one at local parts store fairly cheap and is a great tool to have.. If you don't want to buy one you can rent one at auto zone, Just pay for it then return it..


Ant...

Ant.

I am not sure if the Fuel PSI is the same for your motor verse my moto.. Wait for someone to chime in and see waht they have to say...

Ant...

Bustedback

Did you replace the plugs, cap, rotor, wires, fuel filter, water pump, thermostat, and cooling system hoses, or just slap in the engine as is?

RTorrez1

Personally I would start by pulling any code.
BTW, Your 93 should have 39psi +or- 5psai at the fuel rail.

tlrxj11

Here's what I did, pulled my motor, stripped it down kept everything but the block and head, swapped that and 600 for a 94 wrangler motor with everything still attached but the tranny, I left the distributer and plugs in as well as the Tstat and housing, left the intake manifold and what's attached to that, xjs exhaust manifold, wires, alternator, water pump new upper rad hose, all mounts and pulleys from xj. I never pulled the plugs, maybe ones muffed up idk, I could check it later tonight

DFlintstone

You are still at the lower pressure, till 95, 31 with the vacuum line on the fpr, 39 with it off. In cruiser's tips, right on top in the link in my signature, I think #5 is the sensor ground test. Greyhounds matter allot. I'd check them. Two other, I think you have a ceramic fuel pump ballast resistor there on the inner fender near the air box. You can check it's connections, or just bypass it for trouble shooting. (or forever!) Last, the MAP tube often gets broken....and/or disrespected! > There is a brittle little tube. It comes out of a rubber plug, low on the engine side of the throttle body. It runs back to the firewall, then up to your MAP sensor sort of high up there near center on the firewall. CRUCIAL!! The MAP will tell the ECU to dump fuel with less/no vacuum. Any crack or blockage and it will be pig-rich. (black smoke, fouled black plugs). You can pull the line off the MAP and feel for vacuum with your finger. If it runs!

tlrxj11

That sounds about right, I actually used my xjs fpr which was brand new so that shouldn't be a problem right? And that map hose was actually disconnected at first then I found it and reconnected it and it helped it run smoother, still rough though. Is that resistor a little rectangle tan thing with two connectors coming off that I never knew the propose for?

DFlintstone

Orange wires? Yes. It get's system power to the front and shoots out a few less out it's rear straight to the fuel pump. It's only there because buyers of the 87 complained of the pump being too loud. (Co/Cruiesr). It can be bypassed permanently. I gotta think there is a little less wear on the pump with it in though. It's connections can, and do get funky.

DFlintstone

I'd guess if the FPR is still on the rail, it's the earlier pressure. I'd check those grounds. The breaded off the back of the head, and the gang down there by the dipstick mount. Again, see Cruiser's tips!

DFlintstone

Agreeing with RT, leave the battery disconnected a good while, or over night, then check the codes after the light comes back. The "key Trick" might even work on yours, no harm in giving it a shot!

OBD1 Models: 1991-1995
1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost. Code 55 indicates end of fault code display.