91 S10 Blazer 4.3,,cranks but not starting.

dmizin · 10-02-2009, 09:40 AM

I have a 91 S10 Blazer 4.3 4X4 2 door. I drove to work and parked, 10 hr later going home would not start. Fuel pump is working, put gas in the intake still not starting, injector not working, no spark, the computer has no codes in it, new coil, ignition mod is good, no crank sensor on front of motor, does have one next to the distributor with three wires on it and one behind it on the block with one wire on it.

Thanks
Dave

**octaneman** · 10-05-2009, 06:52 AM

Hi Dave

Apologies for not getting to you sooner.

When there is no fuel/spark going to the engine it is an indication that it is either the ECM or the ignition module. A few tests have to be done in order to rule out the ECM, fuses to the ECM have to be tested, and all ground connections have to be checked and tightened to ensure good surface contact. Voltage readings also have to be taken from the module to the computer. A node light has to be inserted into the injector plug to see if there is pulse width coming from the ECM. Check the distributor rotor while cranking the engine and see if it spins.

dmizin · 10-23-2009, 09:41 PM

Thanks for the help. i check everything and tryed a new ecm and still no change.

Just don't know what could happen in the 10 hours it was sitting when i was at work.

**octaneman** · 10-23-2009, 09:58 PM

Have you checked for power going to the ignition coil including the magnetic pickup with the key on by using a test light ? Is the cap and rotor on the distributor in good condition? Does the rotor spin while cranking the engine ?

If the distributor has a magnetic pick up there is a simple test you can do. Open the the distributor cap and remove the rotor. Then disconnect the plug connector on the far side of the module, there should 2 pins. Put a spark tester on the coil . Place your finger on both pins of the module and with your other hand the positive side of the battery. With the key on, tap the battery positive post and see the spark tester for reaction. If it sparks the pick up coil is bad, if not its the module.

Note : If you can't reach the battery post connect a wire to it and hold the exposed end. Wet your fingers a bit, in this way your body is being a conductor and taking the place of the pickup coil. PLEASE DO NOT CRANK THE ENGINE WHEN DOING THIS.

Please post back your findings.

10-02-2009, 09:40 AM	#1 (permalink)
dmizin Registered User Join Date: Oct 2009 Location: Dayton, Ohio Posts: 2 OS: xp sp2	91 S10 Blazer 4.3,,cranks but not starting. I have a 91 S10 Blazer 4.3 4X4 2 door. I drove to work and parked, 10 hr later going home would not start. Fuel pump is working, put gas in the intake still not starting, injector not working, no spark, the computer has no codes in it, new coil, ignition mod is good, no crank sensor on front of motor, does have one next to the distributor with three wires on it and one behind it on the block with one wire on it. Thanks Dave

10-05-2009, 06:52 AM	#2 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 541 OS: WINXP	Re: 91 S10 Blazer 4.3,,cranks but not starting. Hi Dave Apologies for not getting to you sooner. When there is no fuel/spark going to the engine it is an indication that it is either the ECM or the ignition module. A few tests have to be done in order to rule out the ECM, fuses to the ECM have to be tested, and all ground connections have to be checked and tightened to ensure good surface contact. Voltage readings also have to be taken from the module to the computer. A node light has to be inserted into the injector plug to see if there is pulse width coming from the ECM. Check the distributor rotor while cranking the engine and see if it spins.

10-23-2009, 09:41 PM	#3 (permalink)
dmizin Registered User Join Date: Oct 2009 Location: Dayton, Ohio Posts: 2 OS: xp sp2	Re: 91 S10 Blazer 4.3,,cranks but not starting. Thanks for the help. i check everything and tryed a new ecm and still no change. Just don't know what could happen in the 10 hours it was sitting when i was at work.

10-23-2009, 09:58 PM	#4 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 541 OS: WINXP	Re: 91 S10 Blazer 4.3,,cranks but not starting. Have you checked for power going to the ignition coil including the magnetic pickup with the key on by using a test light ? Is the cap and rotor on the distributor in good condition? Does the rotor spin while cranking the engine ? If the distributor has a magnetic pick up there is a simple test you can do. Open the the distributor cap and remove the rotor. Then disconnect the plug connector on the far side of the module, there should 2 pins. Put a spark tester on the coil . Place your finger on both pins of the module and with your other hand the positive side of the battery. With the key on, tap the battery positive post and see the spark tester for reaction. If it sparks the pick up coil is bad, if not its the module. Note : If you can't reach the battery post connect a wire to it and hold the exposed end. Wet your fingers a bit, in this way your body is being a conductor and taking the place of the pickup coil. PLEASE DO NOT CRANK THE ENGINE WHEN DOING THIS. Please post back your findings. Last edited by octaneman; 10-23-2009 at 10:23 PM.