Thinking about buying a no start $500 XJ

I found an XJ near me for $500. 89 4.0 AW4. It doesnt start, owner says it needs an ignition module and a new battery. Is the ICM expensive? A pain in the ass to replace? Owner says it tries to crank but does not start. Could this be the CPS also? Thanks everybody.

A faulty CPS is a common no start problem.

Yeah if no spark Try CPS first .

Good Luck
Nick

CPS TESTING PROCECURE for 1987 – 1990 4.0 L engines

Test # 1

Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the CPS and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 - 275 ohms. If the CPS is out of that range by much, replace it.


Test # 2

You'll need a helper for this one. Set the volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your helper cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. (That's between 1/2 and 1 volt AC.) If it's below .5vac, replace it.

Everyone likes to jump on the CPS but it could even be as simple as the fuel pump fuse, or a bad rotor or something.

n1ywb said:

Everyone likes to jump on the CPS but it could even be as simple as the fuel pump fuse, or a bad rotor or something.

Click to expand...

True, my bad CPS caused my engine to die after getting warm. But it would still start.

A no-start vehicle is a chance.You can end up with a quick and easy fix or a $500 item you end up trying to part out to get your money back.
At least the engine cranks. It does, yes?
If the rest of the XJ is in good shape and you have to put a rebuilt engine in it (worst case scenario) your still under the 2K$ mark. If the body and interior are in good shape.
I say this because a lot of people sell vehicles that "Just need ___ to get it running"
Got to be careful. People sometimes hide things like a bad cyl by stating it wort spark. Mabye, just mabye.....

A quick trip to the junkyard ought to yield a complete set of spare parts for the FI system. You can test most of the sensors with a multimeter. A compression gauge is about $20 and will tell you if there is anything horribly wrong with the engine, although it's not as accurate as a leakdown test.

You could also try to talk him down.

Does RENIX have an ignition module? The HO doesn't

what do you mean by "module"? Renix has an ignition coil with some electronics attached to it, I usually call that the ignition module.

Some distributors have an ignition control module (a small chip) inside the cap. They are common on cars from that era. The HO ignition does not have a separate control module though.

Quoting the OP: "owner says it needs an ignition module and a new battery. Is the ICM expensive?" when my question is does it even have one

Damn cliff hanger! Did you buy it? What was the solution to the no start? :gee:

This is the renix ignition module

The ignition coil gets bolted on top of it. It's got a transistor or a thyristor or some kind of electronic switch inside, all electronic ignition systems do. Some cars have them in different places, like inside the distributor. The HO has got to have it's electronic ignition bit somewhere. Couldn't tell you where though.