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Discussion Starter #1
Did a head gasket on my H23A, after I put everything back together the main relay failed. I can short the harness to make the fuel pump kick on. Main relay was hot and making a humming noise. What would cause it to fail? Am I missing something obvious?
 

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It's a common Honda issue. Especially in warmer weather, so common that I carry a spare just incase.
 

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Discussion Starter #4
It's a common Honda issue. Especially in warmer weather, so common that I carry a spare just incase.
I know it’s somewhat common, but i find it suspicious that it failed randomly after engine work. Any thing I might’ve missed in the engine that would’ve killed it? Like a short or a missing ground?
 

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It's always possible a ground is making a bad connection within the bay. There should be one from the transmission to battery to radiator support and another from the power steering bracket to valve cover to drivers shock tower.
 

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Discussion Starter #7
Nothing that you could do in the engine bay should cause the relay to fail.
That’s what I determined. I replaced the relay and the fuel pump still ain’t kicking. Thinking my ecu may’ve died. I’ve check the wiring in the circuits they seem fine. Fml
 

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Danny D's second in Command
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My Prelude has been sitting for the past 7 years, and a few years ago I started trying to use it again and it had symptoms of a bad relay. It could be that it sat in the heat for too long and weaken the soldering. I have no idea, but I recall changing it and it still had the same issue. Eventually it went away on it's own, I really think that moisture had built up from it sitting around too long. I recently started driving the car again and I haven't had any issues.

It's a bit of a one-off event, but I just wanted to share that in the event that your car has been sitting around outside for a while.
 

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Discussion Starter #9
My Prelude has been sitting for the past 7 years, and a few years ago I started trying to use it again and it had symptoms of a bad relay. It could be that it sat in the heat for too long and weaken the soldering. I have no idea, but I recall changing it and it still had the same issue. Eventually it went away on it's own, I really think that moisture had built up from it sitting around too long. I recently started driving the car again and I haven't had any issues.

It's a bit of a one-off event, but I just wanted to share that in the event that your car has been sitting around outside for a while.
It’s sat in the summer sun for about 8-9 weeks now. Maybe longer. What’d you do to solve that?
 

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Danny D's second in Command
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I topped off my fuel, because I thought my fuel pump was going bad. I also checked all of the relays, and changed my fuel pump fuse even though it seemed fine. I also checked for any other bad fuses because most cars tend to have fuses that are used for multiple purposes even though it isn't clearly stated on the diagram.

Lastly, I changed my spark plugs, wires and distributor cap.But that was because it was long overdue for it anyway, and I was going on the one-off chance that perhaps there may have been a lot moisture built inside from it sitting outside too long.

You can also google , "prelude main relay soldering". You're going to find a lot of articles and videos of people testing and fixing their main relays. I would start off with the basics though, check for bad fuses, swap around some relays that may be linked to it.

Typically people that experience main relay issues, tend to run into issues in hot weather and the car works fine once the temperature gets colder/ early morning or later in the evenings.
 

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Discussion Starter #11
I topped off my fuel, because I thought my fuel pump was going bad. I also checked all of the relays, and changed my fuel pump fuse even though it seemed fine. I also checked for any other bad fuses because most cars tend to have fuses that are used for multiple purposes even though it isn't clearly stated on the diagram.

Lastly, I changed my spark plugs, wires and distributor cap.But that was because it was long overdue for it anyway, and I was going on the one-off chance that perhaps there may have been a lot moisture built inside from it sitting outside too long.

You can also google , "prelude main relay soldering". You're going to find a lot of articles and videos of people testing and fixing their main relays. I would start off with the basics though, check for bad fuses, swap around some relays that may be linked to it.

Typically people that experience main relay issues, tend to run into issues in hot weather and the car works fine once the temperature gets colder/ early morning or later in the evenings.
I’ve tried replacing the relay with a new one already. Hoping that trying it in the cool air will do it. Also starting to think my ECU may have died, it wasn’t in the best condition anyway. Don’t know how to test that though
 
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