firing problem

[rbk587]

my 87 k-5 has never put me down until now.bout two weeks ago she got to where she wouldnt crank without starting fluid but once running was fine.next she would run then quit when i turned or slowed,i got her back to my work and didnt touch for three days then went out cranked and ran fine so i drove it home yesterday and ran like a top,cranked this morning fine and then just died on me.i tried to refire and the battery was down so i charged it up tried to crank no luck.i pulled spark plug and im getting no fire so my question is whats my best approach without jus throwing money at it?thanks if you have any suggestions

 

[doonjumper]

First check fuses. Continue to follow spark back to distributor. The need for Starting fluid would indicate fuel issue, while no spark would require electrical. The two issues may not have to do with each other.

 

[doonjumper]

i pulled spark plug and im getting no fire

Do you mean you pulled spark plug boot and are not getting fire? OR you actually pulled spark plug out of block, re-atached the boot and are getting no spark that way? Both methods need ground. Did you ground the spark plug/plug boot to the block while starting? Spark plug/boot needs to be grounded.

 

[black dawg]

This is TBI correct?? Check to see if you have injector pulse. These symptoms are pretty common to a bad pickup coil. Even with no fuel or fire, the ether speeds the motor up enough that the pickup coil starts working.

 

[rbk587]

This is TBI correct?? Check to see if you have injector pulse. These symptoms are pretty common to a bad pickup coil. Even with no fuel or fire, the ether speeds the motor up enough that the pickup coil starts working.

ok how do i check for injector pulse

 

[rbk587]

This is TBI correct?? Check to see if you have injector pulse. These symptoms are pretty common to a bad pickup coil. Even with no fuel or fire, the ether speeds the motor up enough that the pickup coil starts working.

tbi is correct and my first thought was pickup coil but wasnt sure it had one.....just replaced rotor,cap and ignition coil

 

[gray dog]

tbi is correct and my first thought was pickup coil but wasnt sure it had one.....just replaced rotor,cap and ignition coil

x2 on the pickup coil

 

[dyeager535]

ok how do i check for injector pulse

Depending on what you've got lying around, a test light works best/easiest.

You can make one out of a dash light bulb, bend the legs out, attach a wire to each leg, wrap with tape to prevent a short, disconnect connector from one injector, one wire to each terminal on the connector, and have someone turn the engine over. If the light blinks you have injector pulse.

If you have an analog voltmeter you can use the same test procedures, just looking for the rapid voltage swing.

Pretty sure you can actually use a digital meter for this test as well, because you aren't looking for the actual voltage numbers, just that the voltage is switching.

The injector circuit operation is simple. Always 12V to one wire of the injector connector with the key in run/start. When the ECM "sees" the engine rotating (via a signal from the ignition module) it starts pulsing the injectors. It pulses the injectors by GROUNDING the injector circuit rapidly.

 

[ccarley]

The pickup coil can be checked with an ohm reading, however I forget what you are looking for off the top of my head. A buddy of mine determined my pickup coil was bad once by watching a timing light; it stopped flashing before the engine died.

The pickup coil is cheap, and well easy to replace if you have the dizzy wrench & a punch to get the pin out of the gear. I recently replaced both my module in the dizzy & the pickup coil, and have been running well since.

Good luck!

 

[dyeager535]

Second post http://forums.carcraft.com/70/661769/general-car-craft-discussion/gm-hei-ignition-module-testing/