ECU leaking orange goop

[Trot]

Howdy again all,

While I've got my 91 CB750 apart and repairing/replacing things, chasing electrical gremlins, etc. I found something.

A while back I noticed an orange sticky sap under the bike sometimes if it sat after a long ride. Didn't think much of it as the bike is old, things leak sometimes, etc.

While pulling my rear fender apart I found the source, it seems this gunk has been leaking out of my ECU, on to the plastic wheel guard in a puddle, then slowly dripping off when it's hot enough.

What is this stuff, and could my bike be having electrical issues from the lower half of the ECU and connector being packed with this gunk? ECU internals burning or cooking off? Thought it might be old dielectric grease but doesn't seem the right consistency, and there's a lot of it.

Thanks in advance!

 

[matthewc]

I literally have the same bike with the same issue you ever find out what it was ? It’s like tree sap under the ECU it dripped onto my rear brake drum

 

[Trot]

Yeah, it's this resin-like potting material coming from the ECU. From my research and observation that stuff can break down over time and/or if there is something electrical failing generating heat, start melting it after longer rides (what mine was doing).

I bought a new (used) ECU off Ebay, swapped it out and cleaned off all the goop. So far so good. I was also having an overvoltage problem (16.5-17V above 1000rpm), thinking it was a bad rectifier/regulator. Turns out it was something going bad with the ECU, sending a weak signal to the R/R, so it did it's job and pumped out more voltage. I have no doubt that and the resin melting were connected. Haven't been riding it much since but so far no repeat issues (either of them)

Also haven't been riding since November. Was on my 1500 Nomad and a truck pulled out and hit me. Broke my left femur and some internal spleen bleeding. Still healing from that wreck.

 

[Rampton]

Yeah, it's this resin-like potting material coming from the ECU. From my research and observation that stuff can break down over time and/or if there is something electrical failing generating heat, start melting it after longer rides (what mine was doing).

I bought a new (used) ECU off Ebay, swapped it out and cleaned off all the goop. So far so good. I was also having an overvoltage problem (16.5-17V above 1000rpm), thinking it was a bad rectifier/regulator. Turns out it was something going bad with the ECU, sending a weak signal to the R/R, so it did it's job and pumped out more voltage. I have no doubt that and the resin melting were connected. Haven't been riding it much since but so far no repeat issues (either of them)

Also haven't been riding since November. Was on my 1500 Nomad and a truck pulled out and hit me. Broke my left femur and some internal spleen bleeding. Still healing from that wreck.

Get well soon brother