Car problems

Tiny
EDHTHREE
  • MEMBER
  • 1991 ISUZU TROOPER
  • 6 CYL
  • 4WD
  • MANUAL
  • 80,000 MILES
1991 isuzu trooper, 2.8 v6. Starts and runs good until you shut it off after it warms up, then it will not start back up, just cranks until it sits for several hours, then it starts up and runs fine until you shut it off.
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Thursday, July 14th, 2011 AT 10:29 PM

4 Replies

Tiny
WRENCHTECH
  • EXPERT
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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Thursday, July 14th, 2011 AT 10:31 PM
Tiny
RASMATAZ
  • MEMBER
http://www.2carpros.com/articles/car-cranks-but-wont-start

Next time it refuses to start don't wait for it to make up its mind-do below immediately to determine if its fuel or spark problem

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 3/16 away from ground-have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, Do you hear the fuel pump come On when you turn key on? If not check fuel pump fuse and fuel pump relay if okay-check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs,coil's resistances,cap and rotor,distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it and keep testing
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Thursday, July 14th, 2011 AT 10:31 PM
Tiny
EDHTHREE
  • MEMBER
Why would it run for hours on end as long as you dont shut it off, then not start up if you shut it off? If it had a part filing wouldn't it fail if the car was running too?
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Thursday, July 14th, 2011 AT 10:39 PM
Tiny
WRENCHTECH
  • EXPERT
Because something electronic is likely getting "heat sinked"
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Thursday, July 14th, 2011 AT 10:57 PM

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