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1994 Jeep Grand Cherokee Laredo 4.0L 4x4 - Starting issues

Jeep didn’t run to begin with when we got it (aka my project vehicle), but we were told that it was because the anti-theft system was engaged. Bought a new ignition w/ keys to disengage the system and that still didn’t work. Replaced sparks and coil packs, checked for spark (which there was) and still nothing. Replaced the computer and battery, nothing. Replaced the crankshaft position sensor and charged the battery, as well as tried to jump it…There was a point where it almost started, but didn’t. Left battery on charger for an hour, still nothing. Did compression test and all 6 cylinders measured around 149 psi. Fuel pump and filter are both brand new as they were replaced before the jeep originally broke down. The only thing we can think of at this point is the timing is off…Any suggestions?

Try spraying starting fluid into the intake and see if the engine runs momentarily on the starting fluid. If it does, it points to a problem with fuel system.

Maybe a problem with the fuel injection relay?

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Tester

I agree with @Tester, use a small amount of starter fluid on the air filter to see if that helps get the engine running. Since the compression numbers were reasonable it seems the valve timing is okay but the ignition timing may be off a little bit. By marking the position of the disty you could try moving it slightly while cranking the engine, to see if that helps get the engine going in case the starter fluid doesn’t help.

I ran into simalar problem recently. I had cranking, fuel pressure at fuel rail, and spark. Used some ether and it fired a little. Was beginning to think injectors. But I emptied the gas tank, put good fuel in and it fired right up and now runs great. You say you just got the vehicle not running, so it might have set for awhile. Could be worth a try.

HOLY PART REPLACEMENTS BATMAN… Thats a lot of items. I would go back to step one and be certain the vehicles anti theft system is actually disengaging. There is also the lovely scenario of when people put aftermarket alarm systems on top of the factory system…usually incorrectly. I would have to repair these regularly as I was doing that sorta thing Professionally when your Jeep was new.

When you turn the key…do you get any security lights? Plenty o people have had to solve this issue…so there’s a lot of info on how to solve and troubleshoot it online.

These are the things I would be looking into forthwith and way before turning any wrenches or changing parts. Methinks your parts are being told not to work, on purpose, by the system.

Look up how to deal with the factory system…I believe you used to use the ignition key in the drivers door and unlock the door then turn key clockwise then counterclockwise or something like that… again the details are online. At this point I think I have forgotten more than I currently know so…that data has been moved elsewhere on me at the moment.

There are TONS of things to read about it as it was a very common no start issue… Methinks your problem lies here somewhere…and also maybe within all the part swapping you just did to add more suspects… lol sorry…I had to throw that in… Lets assume for now all parts are good and installed correctly… go down the road of the security system…

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Boyfriend says he checked the fuel lines, and relay while he was out there a week ago and all seemed fine.

We might do that before we mess with the timing.

The only reason the anti theft system was engaged is because the guy we got it from tried to hot wire it after he lost the original key for it trying to get to work. The only things he’s had done to it otherwise was the fuel pump and oil changes. It’s got tons of leaks so it tells me he didn’t do much preventative maintenance or anything else on it. The only security light we got when we first got it was the anti-theft light and it doesn’t come up anymore after we reset the system.

Go back through the Arm and disarm procedures…

Also… What exactly are the vehicles symptoms at this point? You turn key in ignition and engine engages starter…the engine turns over and wont start/run at all… Or does it seem as though its just about to begin to run/ sounds like its almost there?

Or does it run briefly and just die… Need those stats

It will try to turn over, but won’t. Kind of sounds like when you try to start a car with a basically bad battery. No grinding of any sorts. The battery did need to be charged/jumped, but that’s because it’s just been sitting. It’s brand new, bought it at the begin of December.

OK the battery integrity is rather important at this stage… very important actually. If the batt is dropping below a certain threshold…it will reset your security system again… So as you are trying to arm and disarm…the volts could be dropping too low…and then the procedure starts over again, without you knowing or realizing it. It would be maddening situation actually.

So…suss out that battery… and if you can get a known good one use that. Or a Quality jump pack either on your batt or by itself actually. You need proper voltage and amperes here…In a bad way.

Any troubleshooting is near impossible with a batt that may be out to lunch …especially the security system issue you are working on. You MUST have a good charged battery…with no doubts…

P.S. If memory serves me…when you have a known good batt AND a security system issue… The vehicle seems like its about to start and sometimes even runs for a few moments and shuts down… But you arent there yet… It sounds like its battery time, or use a known good one, However you slice it the battery must not be suspect in this situation.

So basically what you’re telling me is take the battery back and exchange for a new one and try that?

If you cannot be sure of its integrity by testing it with proper tools I suppose I am suggesting this. The battery must be in tip top form…so however you want to go about that… You are in a different boat than most of us here who own shop tools to figure this stuff out. Most auto parts stores will test it for you and inform you of its health. You simply cannot solve this issue if the battery is suspect voltage/amp wise… Trust me on this

A brand new battery, improperly charged or handled, or left to go to zero volts may indeed kill it, not just go dead…but i mean DIE permanently, sometimes they never come back from zero volt land despite being new. They wont take a charge at all…and basically turn into boat anchors. They can even show proper voltage but not enough capacity…some cells die while others are active…it gets silly how batts can fail, but it happens, believe you me. So in this instance do not rely on the age of this battery to believe it is in good form. It may be ok…but it may not be… that is what we need to rule out of the equation here.

There are very specific new battery handling procedures to ensure batt longevity…and letting it completely die is not in that list. So yes…take it somewhere to be tested/charged/load tested on a machine.

There is no way to “mess with the timing.” The distributor is fixed in place. It cannot be twisted to alter the timing.

Had a crank no start with my 1991 Jeep Cherokee. If battery voltage is 10.5 or lower they will not start. New battery solved the problem as the old one would only hold a maximum of 10.2 volts. OP also stated the battery was only charged for 1 hour.