AnotherBoss
NAXJA Forum User
- Location
- San Diego, CA
My 1990 XJ won't start, it has a spark, but it's not strong, the engine will turn but nothing else happens.
-
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1990 XJ Won't Start! :(
- Thread starter AnotherBoss
- Start date
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
Hi. So you and Mr. Clean are trying to get this running.
We've covered some things in that other thread, so be patient if we end up going over some of the same ground.
Cranks, won't start. You have spark but it seems weak.
Ok, lets start with the battery. Can you throw a charger on it? Starters are pretty dumb, they only want amps and they will crank your engine. The engine management system, on the other hand, is a little more sophisticated. It want's to have no less than 9.0 volts or it will start acting weird.
So, lets charge up the battery, then hook up a voltmeter to the battery terminals. You should show about 12.5 volts. Then crank the engine over while watching the voltmeter--how low do the volts drop while cranking?
Also, on the early XJs--yours is a Renix era 87-90 electronics--there is only a single ground for the unibody. It is a braided strap from the rear of the head, driver's side, to the firewall. You should renew this ground, preferably replacing the strap with a 4 or 2 ga cable. Make sure you take the metal contact surfaces down to bare metal, treat the metal with an anti-corrosion material, and make the connections very tight.
Other critical grounds are at the dipstick tube. These grounds are for the ICM--ignition control module (the coil is attached to it with clips), the ECU--engine control unit, and the o2 sensor, plus some other stuff. Again, clean down to bare metal, anti-corrosion material, and make sure they are tight.
Now, the coil is attached to the ICM with clips. Remove the coil and clean the clips and contact surfaces, then treat them with dielectric grease, and reassemble.
Do those things and report back your numbers and any results.
Also, lets keep everything going in this thread from now on. If we get too many threads going info gets lost, things have to be covered again, etc. Let Mr. Clean know we are concentrating our efforts here.
Good luck.
We've covered some things in that other thread, so be patient if we end up going over some of the same ground.
Cranks, won't start. You have spark but it seems weak.
Ok, lets start with the battery. Can you throw a charger on it? Starters are pretty dumb, they only want amps and they will crank your engine. The engine management system, on the other hand, is a little more sophisticated. It want's to have no less than 9.0 volts or it will start acting weird.
So, lets charge up the battery, then hook up a voltmeter to the battery terminals. You should show about 12.5 volts. Then crank the engine over while watching the voltmeter--how low do the volts drop while cranking?
Also, on the early XJs--yours is a Renix era 87-90 electronics--there is only a single ground for the unibody. It is a braided strap from the rear of the head, driver's side, to the firewall. You should renew this ground, preferably replacing the strap with a 4 or 2 ga cable. Make sure you take the metal contact surfaces down to bare metal, treat the metal with an anti-corrosion material, and make the connections very tight.
Other critical grounds are at the dipstick tube. These grounds are for the ICM--ignition control module (the coil is attached to it with clips), the ECU--engine control unit, and the o2 sensor, plus some other stuff. Again, clean down to bare metal, anti-corrosion material, and make sure they are tight.
Now, the coil is attached to the ICM with clips. Remove the coil and clean the clips and contact surfaces, then treat them with dielectric grease, and reassemble.
Do those things and report back your numbers and any results.
Also, lets keep everything going in this thread from now on. If we get too many threads going info gets lost, things have to be covered again, etc. Let Mr. Clean know we are concentrating our efforts here.
Good luck.
