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Hi all -
Great forum! The advice I found here helped me rule out eight possible causes of my Civic (1992 LX manual with 165,000 miles) no-start problem. Alas, it was the ECU.
But...no problem! I bought a 28-year-old civic ECU (the right one for my vehicle) for $200 on eBay, plugged it in and...problem solved!

For a week, anyway. After about six starts and about sixty miles of driving, I went out this morning and...same problem. No-start! Same clues too: with key in position II, CEL comes on but fuel pump does not prime. And CEL stays on.

So I worry there's a hidden short somewhere in my wiring that is...sending a surge of current to the ECU and ruining it?

I have no idea how to diagnose this or if it's even a possibility. Can anyone help me with this?
Many, many thanks! I don't want to throw away my car but...

 
Rep Power: 366

in the 7th gen, there is a famous issue with loose bolts on alternator causing grounding issues that kills ECU's.
check electrical grounding, voltage fluctuations
spikes in amperage causes frying

 
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Thanks - that's something to go on!
So if I find loose bolts on the alternator, I'm in with a chance.

But as for voltage fluctuations, I'm not sure what to do:
Where should I be reading the voltages?
What should the reading be?
What amount of fluctuation is bad?
And what position should the key be in? Position (II)? Or should I have someone cranking the starter (pos III)?
Or is this something that can only be diagnosed with the engine running, in which case...not possible for me.

Many thanks!

 
Rep Power: 366

go look for the ground cables

 
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The bolts on the alternator are tight. Very tight.

I have not tested whether the alternator is working properly (again, I don't know how to do this), but here's another question: assuming it is properly grounded, could a malfunctioning alternator fry the ECU?
(Also, why did Honda not include a voltage regulator or fuse to protect the doggone ECU from damage?!)

Thanks again!

 
Rep Power: 366

car parts stores can check the alternator.
Again, that is common on the 7th, not much on the 6th gen cars.
Different parts could be responsible. A damage wire insulation can cause a spike in amperage. You will need to pull it out to see if there are no issues of wiring shorts. Or loose connectors

 
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Have you checked to see if theres any hacked wires between the ECU and the 2 fuse panels?
Have you checked all of the grounds in the car and the engine bay to make sure none of them are corroded or loose?