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93 2.5 XJ won't start


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Got a 93 XJ, 2.5, Ax-5, 4wd. It won't start. When we picked it up the guy said it needed a fuel pump. Put a fuel pump in it, I've got 35 psi at the rail. Pulled a plug out and grounded it, it's getting spark. Starter turns it over. New cap and rotor, new plugs. Pulled the CPS, it looks good, no cracks or anything, and I'm waiting for my MJ to cool down to I can throw it on there and see what it does. Anything else I should be looking at?

 

I did do a compression test, got 50 in 1, 130 in 2 and 3, 120 in 4. I know that's not the best but I figure it should still fire up. I threw the battery in it from my MJ so I know that's not it.

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Try swapping out the 2 relays on the passenger side fenderwell. These are for the Latch key system. Basically, it turns on the fuel pump, turns off the ignition and cranks the starter over, then once fuel has been put to the rail it turns the ignition back on to start it and kicks out the starter. If no change swap out the ECU. What is the color of the spark? Orange indicates a bad coil when battery condition is known. The spark should have a bluish white coloration and snap when it jumps.

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You have 35psi at the fuel rail, but are the injectors working? Either the fuel is not making it into the cylinders, or the timing is off. Timing is not adjustable, but the plug wires could be hooked up to the wrong plugs...

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Last time it ran, it was sitting at a stoplight, and suddenly died. Guy we got it from said he hooked a scanner up to it, and it told him the fuel pump was dead.

 

Swapped the coil into my MJ and it fired right up, so the coil is good. I'll try swapping out those relays. Right now I'm throwing a good TB on it to check the TPS and IAC.

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What do the plugs look like when you pull them out? Wet with fuel or dry?

Does it try to fire at all, or just spin fast and dead? How long did it sit? Could the fuel just have gone bad? I am also not sure what scanner would tell of a faulty fuel pump. There is no electronic feedback system that the scanner can read concerning the fuel pump. Trying the other TB might not be a bad idea. A bad IAC could give you a no start condition and it is a easy swap to try.

 

Even when you get it running that 50 psi cylinder is going to be an issue.

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Is it TBI? If so, shining a timing light at the throttle body may show the fuel spray to tell if the injector is good (does it have 1 or 2? I don't know much about the 2.5). I know that trick works on my Suburban.

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Have you pulled a spark plug after cranking it, to see if it looks wet or if you can smell gas? Just because the fuel pump is generating pressure doesn't prove the fuel is getting from the rail into the cylinders.

 

When in doubt, try old fashioned stuff. Like -- dump some raw gas down the throttle body and try to start it. It should fire. It won't run for more than a couple of seconds, of course, but it will let you know if it's at least capable of firing the fuel.

 

How many miles are on it? There's another thread running about a 2.5L and a timing chain. Don't forget, the 2.5L uses a timing chain tensioner. If that gets worn out, it can jump timing. That can get very difficult ti diagnose.

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What do the plugs look like when you pull them out? Wet with fuel or dry?

 

Dry for the first many, many times we tried, but the last time I pulled the #1 plug, it was wet.

 

Does it try to fire at all, or just spin fast and dead?

 

It sputters, got it to "run" for about a second before it died, then couldn't get it going again, but that was with the pedal to the floor.

 

How long did it sit?

 

From what I'm told it sat over the winter.

 

Could the fuel just have gone bad?

 

There was no fuel in it when I got it, I replaced the pump and put fresh fuel in it.

 

I am also not sure what scanner would tell of a faulty fuel pump. There is no electronic feedback system that the scanner can read concerning the fuel pump.

 

Me either, I was curious about that myself. The guy I got it from definitly didn't know anything about these, or cars in general. He mentioned how I could get a lot of money for the Torque converter if I had to junk it.:nuts:

-1. Not really.

-2. It's a 5 speed. No TC.

Trying the other TB might not be a bad idea. A bad IAC could give you a no start condition and it is a easy swap to try.

 

Did swap the TB, but what I did(I did this with the coil and MAP sensor too), I took the parts off the cherokee and threw them on my MJ, and the MJ ran with them.

 

Here's what we've tried.

New plugs, cap, rotor, wires.

Tested MAP, TPS, IAC, coil. All worked fine on my truck.

Put a known good fuel pump in, did a fuel pressure test, and I'm getting 34 PSI when you try to start it. Dumping fuel into the TB before we changed the pump never got it to start either.

 

It had been suggested to me to pour a small amount of oil in the one cylinder to see if that would get it to seal enough to fire and run for a few seconds. That did not work either.

 

I would have put my CPS on, but apparently between 91 and 93 they went from the circular 3 pin connector to a oval shaped one. I know that's a very common problem, but I did not have the ability to test it.

 

It is not a clogged Cat, since there is no Cat on the truck.

 

Even when you get it running that 50 psi cylinder is going to be an issue.

 

I'm aware, right now I'd be happy if it idled like crap. The way it's looking though, that #1 cylinder is why it's not running.

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Me either, I was curious about that myself. The guy I got it from definitly didn't know anything about these, or cars in general. He mentioned how I could get a lot of money for the Torque converter if I had to junk it.:nuts:

-1. Not really.

-2. It's a 5 speed. No TC.

 

Torque converters aren't worth a lot of money anyway. catalytic converters on the other hand are. He was probably mixing up the two.

It is not a clogged Cat, since there is no Cat on the truck.

 

So much for that.

 

 

Anyway, if you can't even get it to run pouring fuel down the throttle body, I highly suspect timing issues. May be time to tear into it to check the chain. Or at least see if the distributor is pointing in the right direction with the #1 piston at TDC.

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Still can't get it to go. At 4 deg before TDC on the balancer, the rotor is pointing straight at #1 on the dist. From what I understand that's dead on. Put a good CPS in, that didn't do it. Replaced the relay on the pass firewall between the battery and coolant tank.

 

Is it TBI? If so, shining a timing light at the throttle body may show the fuel spray to tell if the injector is good (does it have 1 or 2? I don't know much about the 2.5). I know that trick works on my Suburban.

 

No, it's MPFI. They went to MPFI in 91.

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Well, I guess that leaves the injectors. Easiest way to diagnose would be a scope, but they are not cheap and hard to find nowadays, but I'm guessing the computer is not letting the injectors open for some reason.

 

The cause could be a sensor failure.

 

But again, I'm generalizing as I'm relatively new to Jeeps and know nothing of the 2.5.

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How many miles are on it? There's another thread running about a 2.5L and a timing chain. Don't forget, the 2.5L uses a timing chain tensioner. If that gets worn out, it can jump timing. That can get very difficult ti diagnose.

 

174k. Pulling the balancer and timing cover tomorrow to check on that.

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Well, I guess that leaves the injectors. Easiest way to diagnose would be a scope, but they are not cheap and hard to find nowadays, but I'm guessing the computer is not letting the injectors open for some reason.

 

The cause could be a sensor failure.

 

But again, I'm generalizing as I'm relatively new to Jeeps and know nothing of the 2.5.

Auto Zone used to sell noid lights. One of them (a GM, IIRC) fits the early Jeep injectors, so it should fit the HO as well.

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