1990 Lexus LS400 won't start. No check engine light.

If it is cranking, have you determined if you have fuel pressure and spark ?

I assume the pump was replaced because it was getting power but no fuel pressure ?
Are you still not getting fuel pressure ?
Spark to the plugs ?
Normal compression when cranking the engine ?
Security light not staying on ?

Hi there:
You will have to pinpoint what the engine is missing...
- Spark
- Fuel
- Compression

All three of these are tested when the engine is being cranked over. There are two way of checking for fuel. Fuel pressure and fuel trigger. Both are very important and must be present for the engine to start. Fuel pressure is self explanatory. You just hook up the gage and see what the reading is. Fuel trigger is check with a noid light. The injector gets unplugged and the noid light gets plugged in to the injector clip. With the engine cranking over, this light must blink. This is the signal to the injectors from the computer. You can have all the fuel pressure in the world, but it wont matter if the injector is not pulsing gas into the cylinder like it should.

Compression tester, spark tester, fuel pressure gage and noid light are all accessible at your local auto store. All three tests play a very important part in diagnosing a no start condition. Be extremely careful when doing these tests.

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You will have to pinpoint what the engine is missing...
- Spark
- Fuel
- Compression

All three of these are tested when the engine is being cranked over. There are two way of checking for fuel. Fuel pressure and fuel trigger. Both are very important and must be present for the engine to start. Fuel pressure is self explanatory. You just hook up the gage and see what the reading is. Fuel trigger is check with a noid light. The injector gets unplugged and the noid light gets plugged in to the injector clip. With the engine cranking over, this light must blink. This is the signal to the injectors from the computer. You can have all the fuel pressure in the world, but it wont matter if the injector is not pulsing gas into the cylinder like it should.

Compression tester, spark tester, fuel pressure gage and noid light are all accessible at your local auto store. All three tests play a very important part in diagnosing a no start condition. Be extremely careful when doing these tests.

using a probe you should be able to hear the injector working, use a noid light to check signal at the injector, and replace the spark plug just for fun

The minimum compression required is 95 psi, below this there is no good combustion, incusive the spark plug gets wet in gasoline
If this condition exists, you should check the piston rings and cylinder surface

It sounds like your battery is dead. Try recharging your battery:)

you need a new alternator

HAVE YOU CLEANED YOUR SPARK PLUGS?? a bad wire can do this too. try changing the wire

Hi again,

Any developments with your Lexus?