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95 Blazer/ Dies, wont start, starts, dies.
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bbks
New User
Feb 7, 2006, 3:54 PM
Post #1 of 2
(3075 views)
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95 Blazer/ Dies, wont start, starts, dies.
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Here's one. 95 Chevy S10 Blazer, 4.3L "W". Drives fine and starts fine anywhere between
15 mins to half a day and then suddenly dies. Cranks over but wont start. Tow it home and
it starts. Next morning, wont start. Later in the day, starts. Replaced ignition control module
and coil. Wont start. Fuel pressure to the rail in spec with 64psi. Spark at plugs checks fine.
Sprayed carb cleaner into intake while cranking and began to sputter. Sounds to me like an
electrically related fuel problem. Tried starting it for a week while checking for a loose connection...
nothing. Yesterday and today, starts fine. Has anybody had a similar experience? Also, just for
clarification, my understanding is that the fuel sending unit on this model is responsible for delivering
fuel to the rail and the PCM/ECM supplies the signal to injector unit. I'm guessing either the
PCM, the injector unit, or crankshaft position sensor. Anybodys help or wisdom would be greatly
appreciated before I continue to throw parts at it. Thanks
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DanD
Veteran
/ Moderator
Feb 8, 2006, 1:32 PM
Post #2 of 2
(3068 views)
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Re: 95 Blazer/ Dies, wont start, starts, dies.
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Are there any stored codes? Not that one will give us the answer but maybe an avenue to start looking.
You may need to have a scan tool connected to this truck the next time it’s not starting that to see if there’s an RPM signal being received, injector pulse commanded, TPS voltage, Map or Mass air flow signals and and and the list goes on.
It could be something as simple (this is only one example) as an intermittent short to power on the TPS signal return line. If the PCM sees anything around or above 4 volts on signal return during cranking it will go into what is called clear flood mode and shut down injector pulse. The PCM doesn’t know any better because the sensor is still within it perimeters; all the PCM thinks is you’ve got your foot to the floor trying to unflood the engine and the PCM won’t set a code.
There are other ways of testing but a scanner is the easiest way that’s if the person using it can interpret scan data properly; scanners are more then just code readers.
Once you’ve narrowed it down to what circuit then you can break out the multi meter and lab scope and start doing pin and scope checks on that circuit.
Like you said you don’t want to throw anymore parts at the truck; so it may be time to take it in and have it diagnosed.
Dan.
Canadian "EH"
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