I would imagine that the fuel pump power is on the same circuit as the headlight is, and that's what the problem is. The headlight doesn't work at times, especially when the bike is running. I checked the voltage to the fuel pump, and I get about .05 volts with the key in the ON position and the bike not running. So, yeah, I must have a short somewhere.

Does anyone know what kind of voltage amount I should expect at the fuel pump? I hooked up the fuel pump to the battery and it works, I can definitely hear it, and it pumps gas out, but that's with 12 volts coming at it.

Headlight doesn't come on, and I think fuel pump is barely putting out because of the circuit that it's on. Something wrong with that particular circuit. I believe. So, does anyone know off hand, what kind of voltage I should expect at the fuel pump, with the key in the ON position but the bike not running? Anyone have a link to the wiring diagram?


1987 or 88, CBR 600

 

You should have about 12V or whatever your battery voltage is available at the fuel pump. On the interweb I typed in ‘manual cbr600 1987’ and there was a link (chrome, google, 3rd entry, first page) to a free .pdf manual which shows the wiring diagram.

http://www.home-business-host.com/im...1987-1996).pdf

The diagram in the manual shows a circuit (fuse) ‘ignition, starter and fuel pump’. There is a different fuse for 'Lighting Circuit'.
A bad earth. Or something is intermittently shorting (directly back to the battery) and so dropping the voltage available to the fuel pump, headlight etc.

Usually such problems are due to bad connections and usually I remove fairings, tank, whatever in order to have a good look at loom and connections.

 

thanks,
Yeah a lot of corrosion on this one. It's been left outside for a while. I'll try to get the guy to put it in the garage, or at least cover it when I'm done.

 

So this is interesting, the fuel pump is allowed to work by way of a fuel cut relay (switch). It's hooked up to one of the coils and a 10 amp fuse. I checked the ground at the fuel pump and get 0 ohms resistance, so it's clearly grounded well. But, only .30 volts when the key is on. Is there a test for the fuel cut relay? It may be correct to have only .30 volts when the bike is not running.

87 CBR 600