1996 Lexus LS 400 does not start

Tiny
BIGGMIKE
  • MEMBER
  • 1996 LEXUS LS 400
  • 170,000 MILES
I put the fuel pump in and the fuel pump relay and when I turn the ignition the pump does not go on can you tell me what else can I do. I don't want to keep putting money into it and the problem is not getting fix thank you for your time please help.
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Tuesday, October 29th, 2013 AT 8:49 AM

3 Replies

Tiny
WRENCHTECH
  • EXPERT
It's not supposed to stay on. It comes on for 2 seconds when the key is first turned on and then resumes when it senses cranking. Test for power arriving at the pump during the first 2 seconds.
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Tuesday, October 29th, 2013 AT 9:14 AM
Tiny
BIGGMIKE
  • MEMBER
Now the pump come on and it still won't start don't know what else it can be help please.
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Tuesday, October 29th, 2013 AT 10:21 AM
Tiny
WRENCHTECH
  • EXPERT
You need to start from scratch.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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Tuesday, October 29th, 2013 AT 11:33 AM

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