Mechanics

CRANK POSITION SENSOR

1998 Pontiac Bonneville • 6 cylinder FWD Automatic • 135,000 miles

1998 bonneville. Crank and cam position sensor replacement?
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Lrankin64
July 25, 2011.




What is your specific question?

Wrenchtech
Jul 25, 2011.
My car turns over but doesn't crank up. Was told crank position sensor. Unknown how to replace.

Tiny
Lrankin64
Jul 25, 2011.
It's unknown if that is the problem also.
Here''s how to find the problem.

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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Wrenchtech
Jul 25, 2011.

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