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90 XJ Turns slowly but wont start.

danny Benavidez

NAXJA Forum User
Location
Texas
Dad just got a 90 XJ. Wont start. Tries to crank up but turns very slowly almost like it is not getting enough get up and go from the starter. Also i think there may be gas in the oil. Is that possible?
 
Dad just got a 90 XJ. Wont start. Tries to crank up but turns very slowly almost like it is not getting enough get up and go from the starter. Also i think there may be gas in the oil. Is that possible?


Gas in the oil is a sign of a leaky injector, or could be from just trying to start it. I would drain the oil and refill and change the filter. The slow crank time will cause the no start issue. The engine needs to reach 300 rpm during cranking to generate a crank signal.
 
87-90 Renix Jeeps need to "spin-up" to 300 RPM before a strong enough signal will be generated from the crank sensor that the ECU will fire the beast.

you need a good battery, good cables, and a good starter. Start with the battery (get it--"start" with the battery).

To much cranking and no start will flood the engine. As said, change the oil.

Remember that when you get the battery/cable/starter issue resolved you will probably have to hold the accelerator pedal fully to the floor, then crank the engine while holding the accelerator down to put the ECU into "clear flood" mode.
 
Flooded engine = fouled spark plugs. Pull at least one and see if it is wet. If it is, pull them all and dry them out. Spray start on the plugs works good.

Like Joe said, maybe you can clear them with the pedal down method.
 
i also say its the battery. may test fine while not under load but wont have enough juice to crank the motor over fast enough.
 
Okay. check battery it is okay. also the vehicle was sitting for approx 6 years. I am having him replace the oil, spark plugs, cables and distributor cap and will check.
 
Only SIX years?

I would pull the plugs, put a little MMO in each cylinder, leave the plugs out and wait a couple days, then with the plugs out crank the engine over a few times. Then put the plugs back in and see how she cranks.
 
I'm with Joe on this. Put some Marvel down it let it soak in a while, and crank it sparingly without plugs. I think I might do the first couple of revolutions by hand. If there's gas in there as well as having sat for six years that poor thing must be dragging, and you don't want to score and gall the cylinders. If it does start, you'll get a cloud of smoke, but that will clear when and if things normalize.
 
Dad just got a 90 XJ. Wont start. Tries to crank up but turns very slowly almost like it is not getting enough get up and go from the starter. Also i think there may be gas in the oil. Is that possible?

Try tapping on the starter solenoid, mine was doing similar things and this simple problem fixed it. Give it a few whacks on the end with a small blunt object. :explosion

If that does fix it, the starter is on its last leg, could last many more months, never know, have it tested.

Also try cleaning the connections to the starter, and grounds to engine, the combination of those few things made it start better then in recent years.
 
Try tapping on the starter solenoid, mine was doing similar things and this simple problem fixed it. Give it a few whacks on the end with a small blunt object. :explosion

If that does fix it, the starter is on its last leg, could last many more months, never know, have it tested.

Also try cleaning the connections to the starter, and grounds to engine, the combination of those few things made it start better then in recent years.

Those were my first thoughts - until I saw that "sat for six years" bit.

Concur - MMO down the plug holes, let sit a bit, and then test crank. If you can't get Mavel Mystery Oil locally, mix auto trans fluid 3:1 with acetone and use about a tablespoonful of that down each hole.

If it cranks over better (charge the battery, pull the starter and have it tested while you're about it. Charge the battery with as low a charge rate as possible - under 5A is good, 1A is best;) then change the oil, put the plugs back in, and see if it kicks over.

If it doesn't, you've eliminated at least one problem. Once the starter and battery are "known good" and the engine cranks over quickly, look at your CKP (CranKshaft Positon sensor) next. It's a common cause of "crank, no start" issues on XJs in general.

Another good thing to check is the silly little ground strap from the cylinder head to the firewall - probably just replace it outright, since it's twenty years old. Better to use actual wire - use 10AWG as a minimum size, with a 1/2" ring on the engine end and a 3/8" ring on the firewall end.

Alternatively, just run the other end of the chassis ground (that's what it is - the primary chassis ground. A/K/A "The RENIX Killer") to a screw that's easier to reach - one of the fuel rail mounting screws will work neatly. You can then use a 3/8" ring instead.

That ground strap is the primary ground channel for the chassis. All of the sensors ground to the engine block, the ECU (Electronic Control Unit) grounds to the chassis. If that strap is failing or contaminated, it will raise all sorts of Hell with your sensor signals - and cause crank, no start issues of all varieties! This can be tended to while you're soaking the rings in MMO or ATF/acetone and charging the battery.
 
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