Fuel Cut-off relay issues - Honda Shadow Forums : Shadow Motorcycle Forum

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Old 12-13-2012, 01:44 PM   #1 (permalink)
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Default Fuel Cut-off relay issues

I think I've read all of the other posts regarding this topic, but still didn't find exactly the info I'm in need of...

My new (to me) 1996 Shadow ACE 1100 developed a little issue recently. After sitting for a few weeks, it started and ran for about a minute before it quit.

Checked spark - all OK. Checked fuel flow at the petcock - all okay.

Got on the computer and headed straight to this forum, and learned to check the fuel cut-off relay. I removed the relay and jumped the black/black-blue wires. It set the pump to clicking, and the bike started and ran just fine again. Hence I figured the issue was the relay.

Next step, a call to the local Honda dealership for a new relay - cost - SEVENTY SEVEN DOLLARS! Yikes! I bit the bullet and threw my money down.

Got home, installed the new relay aaaand....same problem. Went back to jumping the two wires, and it's back to running fine.

However, my OCD isn't happy about the fact that it now is bypassing the safety feature. I'm not sure how to test further. I downloaded a manual, but the info is vague.

After searching and reading further threads on this forum (what a wealth of information this site is! Love it!) I went back out to the garage to run one other test. I ran the positive tip from a volt meter to the blue/yellow wire, and other end to ground. It read just under 12 volts when the ignition was turned on. Now I'm not sure what this tells me. Should it have voltage? What do I do with the info I currently (no pun intended) have?

On a side note, I have different numbers on the backs of the old and new relays. They both say "CF318", but under that the original says "2.3" (and below that "081")and the replacement says "5.0 (and below that "011"). Are they interchangeable?

I think my next step is to check for continuity between the black/black-blue wires when the blue-yellow wire has voltage. Is this correct?

Any help or insight is most appreciated!
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Old 12-13-2012, 04:24 PM   #2 (permalink)
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The blue/yellow wire will have voltage as it is connected to the junction of the coil and the spark unit. The spark unit will be open and not pulsing to ground, and the high side of the coil is connected to the + side of the battery. The relay is looking for the ground pulses on the yellow/blue wire when the engine is running to switch power from the black wire to the blue/black. Your jumper wire takes the place of the relay bridging the black to blue/black wires to send power to the pump.

I would check the yellow/blue wire continuity to the spark unit. This will make sure that the ground pulses are making it to the relay.
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Old 12-13-2012, 07:53 PM   #3 (permalink)
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Thanks Dave.

I will test that, once I figure out where the spark unit lives. Also, if the spark unit was the cause, I also wouldn't be getting spark on one of the cylinders, correct? I'm hoping I can rule that out...
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Old 12-14-2012, 10:27 AM   #4 (permalink)
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If both cylinders are firing ok, then the spark unit is healthy. The pump may still be the culprit as they can fail intermittently.

I was too cheap to buy the stock relay and the safety factor is somewhat overrated. Bike engines can continue to run when laying down, and the fuel system will leak without the pump running. I did make one change for safety as my ignition switch is located down on the left side of the bike which makes stopping the fuel pump a challenge in about half of the lay-downs. My fuel pump is switched by a standard 12v relay that is triggered from the kill switch power.

Good luck!
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Old 12-14-2012, 10:48 AM   #5 (permalink)
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I'll take a long shot guess on this one......the carb pilot jet has crap in it.
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Old 12-14-2012, 11:26 AM   #6 (permalink)
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MinnesotaGreg, it is definitely running out of fuel, rather than the pilot jet (I've cleaned the carbs thoroiughly). Once it stalls, I bridge the wires and it fires right back up after the pump runs for a few seconds to reprime the carbs.

Verdeta,

I've opted to leave the relay out of the circuit. I tested the wires to the relay last night using the Haynes manual method. Checked for voltage to the black wire with ignition on - had about 11.5 volts. Checked continuity from the black/blue wire to ground - had about 2 ohms of resistance.

After this I also checked AC voltage at the blue/yellow wire with the engine running, and it read around 24-26 volts. I am guessing this is reading the pulses (alternating current?) with my mulitmeter. At the same time there was still fukk resiustance between the black/blue and the black wire.

Is it possible that the new relay I purchased is defective? Slim chance I know, but it wouldn't be the first time I got a new defective part...
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Old 12-14-2012, 01:49 PM   #7 (permalink)
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So I had an electrical engineer here at work test both the old and the new relay - both seem to be faulty. Is there anything that could cause the new relay to short out in some way? Or did I just get a bad relay?
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Old 12-14-2012, 02:51 PM   #8 (permalink)
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Good luck convincing the dealer it was a bad part. Most places have a "sales are final" policy on electrical parts.

Use caution when measuring the blue/yellow wire; when the coils fire there is a huge spike on this wire. I looked at the voltage on my scope and it was nearly 200 volts. I think this is why these relays are short lived.
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Old 12-14-2012, 02:56 PM   #9 (permalink)
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Jump battery power to the relay and see if it operates.
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Old 12-14-2012, 03:02 PM   #10 (permalink)
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My voltage read 24-26 volts at the yellow/blue wire when running. I can't imagin it cooked the relay.

I'm not sure jumping battery power will work, as it nneds a pulse current, not a direct current. Or am I wrong about this?

Would it be possible to cook the new relay if I had the battery on a charger when I plugged it in?

What WOULD possibly cook the relay, other than age?
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