Random Start

[Musada]

90 LS400

A few weeks ago when i was leaving from work. My car wouldn't start. It would keep turning but no start. Finally after about 20 mins it decided to start. A couple days ago, the same thing happened, only it wouldnt start. Let it sit for a few hours and still nothing. Finally paid for a tow and had it hauled to a shop only for the shop to tell me the car started and theres not much they can do since it started fine. So i wasted money for a tow on that. This morning it happened again. It would just turn and no start. But finally cranked about 5 mins later. Anyone have any ideas on what it could be. Check engine light isn't on. btw

[fsuguy]

You probably should begin eliminating things one at a time - first check to see if your coils are good; there is testing process that requires you to check the resistances between primary and secondary windings. Once you eliminate the coils as a potential source of the problem, move onto the fuel, etc., etc. By the way, you would get more helpful responses if you provided some more background information like whether you had any work done on it, whether it has been sitting idle for a while, whether you just got it, or other problems leading up to this issue, for anyone choosing to try and provide some guidance.

[Musada]

Sorry...Well so far Over the last year I've replaced

-Crankshaft Sensor + bad wiring

-Timing belt, Water pump, Thermostat

-Fuel Pump, Fuel filter

-Starter, Alternator, Battery

-Both Catalytic converters

- Ignition coil closer to the driver side

Check Engine light is not on. My car is now overheating as well. Temperature gauge stays in the middle while driving, but while stopped, begins to rise very high. I don't think the electric fans are coming on..Thinking it may be the radiator fan relay. What do you all think?

[1990LS400]

The weather has to be quite hot before the electric radiator fans turn on - at least it did on the 90 LS I had for 13+ years. I would be suspicious of the thermostat or even of an inadequately refilled cooling system. If you would provide your location in your profile, we would know what type of weather you are driving in.

[landar]

As I understand, the electric fans are primarily for use when the AC unit is running. You have a main, mechanically running clutch fan that should pull lots of air thru your radiator when stopped. Check that fan for proper operation.

Concerning the no start situation, I would be ready to check the spark when it won't start. Take off all the plastic stuff around the coils so that you can easily get to the main high tension wires to check for spark. One thing that many early LS owners seem to overlook is the distributor caps and rotors. Those rotors do not last forever and need to be periodically replaced as a wear item. May not be your issue but keep it in mind.

If you have spark, then you may want to check the fuel delivery next. I would spritz a little starter fluid into the throttle body or intake snout the next time it fails to start. If you get even the slightest hint of the engine trying to run, then you should go down the fuel path. I know you recently replaced the fuel pump and filter but you can get bad parts particularly if they are cheap knockoffs as are so prevalent from the local parts houses.

Finally, with a 90 LS, you could be battling the leaky capacitor syndrome. The caps in the ECU will begin to leak and then the computer no longer acts reliably. Again, it may not be the issue but be aware. Also, the trunk wiring in a 1990 can also cause strange electrical issues.

Be methodical in your search and you will soon get to the root cause.