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no spark

vettester vettester
New User | Posts: 7 | Joined: 04/11
Posted: 02/20/13
12:04 PM

I have a 1989 c4, I made a mistake of leaving the diagnsostic jumper jumped and then i started the engine and then it quit,and now it turns over but wont start? please help.?thanks!  

waynep71222 waynep71222
User | Posts: 181 | Joined: 04/12
Posted: 02/20/13
06:05 PM

jumping the A and B on the diagnostic port WILL NOT EFFECT the engines ability to start or run.. you have a different problem..


a few things for a no start test...

is the security light flashing???  while attempting to start the engine.. if so.. pull the key out and wait just over 4 minutes for the time out to expire and try again..  VATS system..

when you turn the key to the RUN position from the OFF.. do you hear the fuel pump run???  perhaps some help.. the fuel pump should turn on for only 2 or 3 seconds when you first turn the key on but before you crank the engine.. this builds up pressure in the fuel rail for easier starting..   the fuel pump should also come on while cranking...

so.. does the fuel pump run as described above??

next...   got spark???  i usually revert to a timing light with some strong rubber bands holding the trigger on or some tape... i position the clamp on any wire thats available.. then  i aim the timing light at the windshield so i can see the flashing light if the ignition is firing properly...


other forum members have had issues with the ignition switch on top of the steering column under the dash.. when it fails it acts weird.. it will crank and fire up but as you release the key it will die..  .............

post what you have.. i will be around...  

waynep71222 waynep71222
User | Posts: 181 | Joined: 04/12
Posted: 02/21/13
07:55 AM

wait.. a second.. you started this... no spark..


got a test light????

probe the red wire into the BAT terminal on the side of the HEI...

you should have power there when the key is on...  and while cranking....

yes or no...

since you have not responded so far.. i am taking that either you have found the issue.. or are busy off at work..

i will be around if you have more issues..  

Bobs427 Bobs427
New User | Posts: 8 | Joined: 02/13
Posted: 02/21/13
03:37 PM

One other thing you can try. Go to the TACH lead at the HEI. Using your test light, have someone crank the engine. If the test light "DOES NOT PULSE" replace the ignition module.

Bob Aka-pepsi1  

vettester vettester
New User | Posts: 7 | Joined: 04/11
Posted: 03/30/13
01:00 PM


waynep712222 waynep712222
User | Posts: 129 | Joined: 03/13
Posted: 03/30/13
07:44 PM

vettester posted.


DISTRIBUTER..  the Whole thing.. ??

IGNITION,  which part. the Ignition Switch??

FUEL PUMP,  in the tank.. with a new strainer i hope.. this does not effect the spark..

INJECTORS.  ????  wait.. does it run on carb spray??


lets start again....

do you have power at the RED wire to the HEI BAT TERMINAL??



see the red wire...  thats the one i want you to probe with a test light..  with the probe shoved into the cap with the coil cover removed... slowly operate the key from the OFF position to the RUN position and the light should come on.. then up thru the cranking position.. the light should still stay on...  when you release the key.. to the RUN position the light should stay on.. when you turn the key to the off position.. it should go off..

there should NOT be ANY.. flickering of the light from the moment you turn the key to the ON position thru the cranking and back to the RUN position..   if you have no light.. then we have to check the ignition switch and the power wires to and from it..

this is the HEI cap to module harness.. did it come with the new/reman distributer.. its a U518 at az stores. i have found these with wires broken down near the strain relief..  it prevents power from reaching the module.. or from the module from being able to control the ignition coil.. the black wire  ground the black wire coming from the coil.. and is part of the SPARK return path..


this is the HEI ground strap.. goes under the coil in the cap HEI caps..

HEI Largecapgroundstrap

did you replace the IGNITION COIL also.???

this is the VATS system ignition lock cylinder


when you insert the ignition key.. and turn it to the RUN position.. does the Security light go out??? it should.. if the security light flashes.. you could have a bad vats system.. it usually does not cut the ignition power but it does cut the signal to the fuel injectors preventing the engine from running..

this is the L98 HEI distributer that uses electronic spark timing. there is a missing harness from the far end of the module.. that connects to the ECM...

lastly.. does the distributer rotor turn when you crank the engine??? yes.. you have to have the cap off to see this.. and i know what a PAIN this is..

one more thing... there is a second electrical connector coming out the side of the distributer.. it connects to the EFI harness.. UNPLUG it..  use a timing light over a spark plug wire...  crank the engine.. there will be NO fuel injector pulse.. but the HEI should create spark...

lastly.. did you change the ROTOR.... i have found many burned thru.. and allowing the high voltage to go right to ground..

do pick up the private message.. so we can talk about this..  

waynep712222 waynep712222
User | Posts: 129 | Joined: 03/13
Posted: 03/30/13
08:08 PM


when you JUMP the A and B on the data connector...

DOES the check engine light flash CODE 12... without the engine running???? key on.. a and b jumped..

if it does NOT flash a code 12.. the computer is NOT active..  there is a multi page diagnostic chart with the OBVIOUS title.. Won't flash code 12...  

waynep712222 waynep712222
User | Posts: 129 | Joined: 03/13
Posted: 03/30/13
08:26 PM

can you find this terminal block over on the drivers side of the firewall.. directly behind the battery tray... as you can see the battery hold down bolt right next to it..

87 C4 Powerdistributionterminalblock

you will want to probe each of the individual wires.. the second segments.. as the soft insulation sections are fusible links.. and protect the cars wiring harness from burning up if there is a short...

there should be power on each one of these wires from this terminal block. when you probe them...

since you will probably have the battery out while wire brushing the various terminals while you have them removed from the stud.. find this ground circled in green...

its got a ground wire on it.. and can cause you issues if its dirty like this one is..

87 C4 Underbatterygroundconnection

these are from an 87.. your probably has similar as 87 to 89 models were very close..  

waynep712222 waynep712222
User | Posts: 129 | Joined: 03/13
Posted: 03/31/13
05:00 PM

i have a stupid.. idea...

do you feel like pulling the HEI back out completely...

got a some kind of metal surface... cookie baking tray.. almost flat air cleaner cover???

with the HEI out... rig up a wire to go from the BAT terminal on the cap..   so you can clip it to a positive battery post..

take a pair of jumper cables..     one red and one black.. hook both to the NEGATIVE battery post...

hook one of the other ends to the metal plate... hook the other to the distributer housing..

now.. turn the distributer upside down... the cap is installed..   place the top of the cap on the metal plate so the terminals are evenly spaced  away from the plate...

now you can hook up the wire from the HEI bat terminal to the positive battery..   now.. spin the gear.. sparks should jump from the cap terminals to the metal plate.. this proves the HEI is functioning in a normal matter..

if you always position the cap terminals evenly from the plate.. it will NOT shock you..    be sure to DISCONNECT the cable to the POSITIVE first...

i am waiting for a friend to come by with his professional camera and cam corder to get some really great images of this procedure...