90 Honda Accord

I've been having a problem with my 1990 Honda Accord.

When I started having the problem, the car would run for a couple of minutes,
then it would just shut off. Shortly after, it wouldn't start at all. So, I
replaced the main relay, and it still wouldn't start (I'd hear only 1 click).
There's no power to the fuel pump, and I also lost the ignition spark. I
checked the continuity of the wires in the relay. When I measured it with a
digital meter, the wires showed continuity. However, when I tested it with a
light probe, the bulb didn't light up (which leads me to believe there's no
continuity). I switched the ECU, and that didn't help either. The ECU
powered up when I checked it.

If anyone can point me in the right direction from here, I'd appreciate it.

Thanks

 

did you replace it with a new one or a used one?

 

The relay was brand new. The ECU was used but in working condition.

 

Ignition switch?

 

The ignition switch is working fine.

 

It sounds like you lost power to the ECU. There are multiple
location where power enters the ECU. No power, no spark, no fuel.
Does the check engine light comes on then goes off and able to
retrieve codes? Secondly, got signal from the crank sensor?

 

When I turn on the ignition, the check engine lights stays on the whole time.
How can I find out whether the ECU powers up?

Thanks for your help.

 

If your Check Engine light comes on, your ECU *IS* "powered up".

Honda ECUs are reliable like the sun. Don't change it.

Check for error codes stored by the ECU:
Pull carpet back from passenger footwell.
See the red LED?
Turn ignition to ON, but not to START.
If LED flashes, codes are stored.
Count flashes. There may be both long and short. Sequence will be separated
by long pause. Multiple codes may be stored, so watch carefully.

Long blink=10
Short blink=1
Sequence long-short-short-short-short=code 14.

Your symptoms sound like a bad ignition switch or igniter. does your tach
act oddly?

 

I checked the error codes stored by the ECU, and I found code 14, which is
the Idle Air Control valve. The code was there before the car stopped
working, though. I replaced the ignitor and the ignition coil, neither of
which helped. I checked the ignition switch by turning it on, and the engine
light, the battery light and the oil light came on. I still only get 1 click
on the main relay.

If I ground wire 8 on the main relay, the fuel pump starts working. I still
don't have a spark, though.

I'd appreciate it if you had any other ideas. Thanks!

 

<snip>


That doesn't mean the ignition switch is OK.

It's still the main suspect.

 

I think I see your problem. If you turn on the ignition, you hear one
click, the check engine lights stays on the whole time, no code
16 and when you supply ground to terminal 8 the fuel pump
runs then it sounds like you have no power to the ECU.

Honda ECU's use multiple power inputs for a reason. To warn us.

The main power to the ECU originates before the main fuse, near
the battery. Check for corrosions or wiggle any wires to make the
check engine light go out while the ignition is switched ON. Once
the light goes out, it should start.