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PDBoulder

Relay Failure

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Hi,

I have a new to me 2003 Lemans that just last week experienced a relay failure. Heading home after work, it was about 98 degF traveling about 80mph and the bike started cutting out, bucking pretty bad. I managed to make it home, about another ten miles. I had just purchased a tank of gas and suspected that I kicked up something in the bottom of the tank that was causing the intermittent cutout. Pulled the pump and filter, replacing the filter. Nope, that wasn’t it. The bike would still cut out. By pure luck I noticed that relays #4 and #5 were very hot. The prior bike owner provided me with several new Omron G8HE-1A7T-R1-DC12 relays. Sure as shit, replacing relay #4 and contact grease solved the problem. The problem is that today on my way home from work in 85 degree weather the new relay failed. At lunch I had put 70 miles on the bike in and around boulder canyon. Bike ran flawlessly. Air temp was about 80deg. I tested the old relay and it tests fine 83Ohm coil, and 0.1 Ohm contact resistance? So, what is the root cause of the relay failure? Is it the female spade connector losing its spring when hot? Oxidation on the blade? The old relay even when the bike had cooled down still failed in slot #4. Any insight would be greatly appreciated.

Paul

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not sure what 4 does, but 5 runs the fuel pump. did you replace all relays? if not, do that first. smarter people will chime in with help. welcome Paul

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Clean those connections (mounting block) with something like CRC Electronics Cleaner, and treat with "something like" Caig DeOxit®. (There is nothing like it.)

Pull the relays straight out. Don't wind them around or you'll be repairing the tiny, flimsy connectors in the bases.

Most importantly, install the GH8E in all positions, but especially #5.

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Which relay is now getting hot? 4-5 or both again? If it’s 5, maybe the pump is burning out?

both prior suggestions are the key. Cleaning up the contacts and making sure they are tight eliminates those variables.

being a music lover and stereophile, caig products are excellent. I have a bunch of it at home and use it on my equipment. 

I bought a little tube of it and brought it with me when I picked up my new to me Scura. Cleaned and replaced the relays and fuses before I ever started it under my stewardship.

I would check the ground/power to the pump. That’s my gut feeling. Loose connections, bad/pinched wiring etc will cause heat.

 

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Thank you all for your recommendations. When I replaced the two relays, I used CRC Electronics Cleaner on the socket and terminals as well as smeared dielectric grease on the terminals.

Mikko, It appeared to me that both #4 and #5 were getting hot. It seemed that by process of elimination, relay #4 was the culprit. I will look for the pump ground to eliminate that possibility as well.

MartyNZ, that link is what I needed. I'm thinking the female spade connectors must have relaxed and need to be tightened up.

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smeared dielectric grease on the terminals.

Not good. Relay manufacturers will tell you to keep that stuff away from their relays. There is some chemistry involved, but I would never use dielectric grease on any bike that has relays, except for the spark plug boots. Period. Apparently, it can even cause gas that travels in the wiring harness and get to the relays.

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Yup...you may have inadvertently created a situation you didn’t realise by trying to do what you thought was a good idea. No worries! Governments been doing the same for thousands of years 😄

try a bottle of this here magic elixir:

CAIG LABORATORIES D100L-25C Contact Cleaner

you’ll be glad you did!

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hmmm, wait, I see the relays the PO provided are "1A7T" . . . not 1C7T?

These four blade relays?

If so, do not use in Position #1 (Start)/ at the front of the stack. This requires a five blade relay.

 

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Also, PDBoulder, look at this temperature data. Others also listed some temperature data to see on that thread. Expect the last relay (#5) to run hotter as it is the coils, injectors, and fuel pump.

 

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Hi docc, Mikko

I have both relays 1A7T and 1C7T.  It's possible that the heat generated by#5 affected #4.

I ordered the DeoxIT. Should have it in a day or two.

I hope to be able to work on it this weekend.

 

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Yes, #5 affects #4.

The advantage to using "Form C" is they can be switched around into any position. Only Position #1 (Start) requires Form C/ 5-pin.

You're on the right track, buddy!

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On the advice of the Good Docc! Prescribed 5 relays and didn’t need to call in the morning :)

697qSfY.jpg

 

 

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