Dog Noise Mastiff EFI.

Cruz Dog

Active Member
So i finally lined the tank replaced the fuel pump and fuel screen, got it all ready and i go out to start it and its still making that buzzing sound coming from the relay the relay is good. was told it's prob the EHC.
 

stlmikie

I wish I had more money.
I may be way off but I don't think your ehc has anything to do with the edit. Two separate systems? Like I said I could be way off. Is the bike running? Outside of the "buzz" what else is going on?
 

ksmike

Active Member
Have you bypassed the relay to see if the fuel pumps runs? Have you checked the coil voltage on the relay? Does the fuel pump run for a second when the run button is pushed? Just looking for trouble shooting info.

Here is a website that explains how simple relays operate.

http://www.bcae1.com/relays.htm:D
 

Cruz Dog

Active Member
No i havent done any of the above ill check out that website you just sent so i can get a better understanding.
 

Jwooky

Well-Known Member
Relay is buzzing because not enough voltage. If you check on the signal side (smaller gage wires) you will find less than 12v.

The EFI supplies ground to the relay. If you ground you will close the relay. Sorry to say you may have a bad EFI module.
 

Cruz Dog

Active Member
no havent replaced it. I inerchanged the one for the horn and fuel pump both work on the horn. could it work on the horn and not the pump?
 

ksmike

Active Member
You could check the voltages on the relay, with a digital voltmeter. If you are not familiar with checking voltages, best not try that or bypassing the relay. It would be easy to short things out and make matters worse. Looking at the wiring diagram, it seems that the relay control voltage comes from the EHC and goes through the EFI module, so could be either one....maybe. Have you tried removing the fuel pump relay to see if the "buzzing" stops? Could also be a bad ground on the EFI module....??
 

Cruz Dog

Active Member
Thanks for the help. I did remove the relay and the buzzing stops. Where is the EFI ground wire located so i can check it.
 

ksmike

Active Member
I believe most of the ground wires are to the frame in the battery area. Take the battery out, for safety's sake and look at the wires in this area. Unbolt any ground wires you find and make sure it has a good crimp connection on the wire, look for dirty, or loose wires, look for rust under the bolted connection to the frame. Be careful working with the battery in its tight confinements. It has the ability to discharge 100's of amps should it get shorted to anything. Take the negative cable off of the battery first and isolate it, then you can safely work on the positive terminal.
 

ksmike

Active Member
Also, If you could take the side covers off of your bike around the battery area, and take a couple of good pictures and post them, I would know more about what direction to point you in. A top picture of the battery area, and a picture of the relays would be good.
 

Jwooky

Well-Known Member
VFI/EFI ground is the small black wire on the relay. You can ground it and see the noise will stop. The only way I know to verify for sure the module is good is to send it to S&S.

I can just tell you from experience that this is most likely the cause.
 
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