Update: 1991 Accord - No Start - No Spark

I posted a question regarding no-spark on a '91 Accord last week.
Problem solved: It was the coil. That is so strange considering the
car ran when parked. I figured a bad coil would cause a breakdown, not
a no-start.

Diagnosis went like this (steps 1-5 done before the last post):

1. Key on causes fuel pump to cycle. Thus, ECM probably okay.

2. Checked spark at a cylinder - nothing.

3. Verified cam was turning through oil filler cap: Cam turns, timing
belt must be okay.

4. Removed cap, checked spark from coil high tension post: Nothing.

5. Checked coil resistance - .7 ohms low side, 12k ohms high side
(disregard last post on this - I measured the high side incorrectly).
Note: These readings are in-spec!

6. Removed ignitor from distributor and performed bench test procedure
from tegger.com - Passed!

7. Bench tested the coil: No spark from high side to ground - BUT,
just enough to cause a mild shock from high side to _positive_ terminal
of low side. Looks like a bad coil.

8. Connected small light bulb in place of the coil and cranked the
engine: Light flashes.

Number 8 was what finally convinced me to replace the coil. Installed
a new one and the engine fired right up. I went ahead and replaced the
cap, rotor, plugs, and wires because their condition undoubtedly caused
the problem to begin with.

Thanks Elle, Jim Yanik, Thom, motsco, and Tegger!


-rev

 

If the internal coil insulation breaks down at HV,you could get a good
resistance reading at the low volts any meter uses for measuring
ohms,(IIRC,~2volts)but when the coil pulses,the HV breaks down the
insulation and effectively shorts itself out,thus not enough voltage to
make a spark.


Good to hear your problem is solved!