Electric fuel pump musings...


Information and questions on GL1200 Goldwings (1984-1987)
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tom84std
Posts: 493
Joined: Fri Jul 13, 2012 7:40 am
Location: Arlington, Texas
Motorcycle: '84 STD 1200
2002 VTX1800
2007 Shadow 750
69 BSA Bitsa
2004 Virago
VW Trike

Electric fuel pump musings...

Postby tom84std » Fri Sep 21, 2012 10:20 am



On my '84Std I had a fuel pump fail me a couple of weeks ago. I replaced it with an automotive unit simply connected to the ACC+ circuit and rode out the rest of the trip. I was baffled by it's connection to the ignition control circuit. In the parking lot out on the road I connected a test lamp to the pump's input wires from the IGN control box. Neither wire ever went to +12V even when I switched the ignition to RUN. I assumed there was a problem with the fuel pump's power circuit. The function of the ign. control was a mystery to me. With the pump connected directly to the +ACC circuit, the pump ran whenever I had the key on. I wanted it to function more 'factory'. This morning using a simple test lamp and digital meter, I got to the bottom of it.

The factory pump is connected via a two connector plug to the ignition control module. One wire, black/blue stripe, provides the switched +12v to the pump. The other wire in the connector is solid green. The green wire is directly connected to frame ground - and is not switched.

Turn the ignition key to the ON position, the black/blue wire remains dead, not energized. The reason I had thought there was a problem out on the road.

Hit the starter switch and the black/blue wire immediately swings high to +12v and remains that way for as long as the key is in the ON position, even if the engine dies.

Turn the keyswitch OFF and the black/blue wire goes dead.

Return the keyswitch back to the ON position the wire remains dead until you once again hit the starter button.

When you hit START, the black/blue wire again goes high +12V and again remains that way until you turn the switch to OFF, whether the engine is running or not.

Feels good to finally solve a mystery that's baffled me for over a week.



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feetup
Posts: 100
Joined: Mon Jun 29, 2009 1:15 pm
Location: West Coast of Canada
Motorcycle: 84 GL 1200I
75 GL 1000 (in pieces)
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'56 Norton 600

Re: Electric fuel pump musings...

Postby feetup » Fri Sep 21, 2012 11:02 am

I'm a bit surprised that there is not a dead engine safety built into that circuit. The way it is, if we crash the bike there will be fuel dripping out of the carbs or the broken fuel line till the bike is switched off.

Good to know how it works though, thanks for sharing that.

User avatar
tom84std
Posts: 493
Joined: Fri Jul 13, 2012 7:40 am
Location: Arlington, Texas
Motorcycle: '84 STD 1200
2002 VTX1800
2007 Shadow 750
69 BSA Bitsa
2004 Virago
VW Trike

Re: Electric fuel pump musings...

Postby tom84std » Sat Sep 22, 2012 12:42 pm

Had a bad wreck last April and got a few broken bones and myself whacked on the head pretty good. I was gone for about six weeks until I was able to go home, but what had been undetected during all that hospital time was my sudden bouts of vertigo.
On my second day home I was feeling like a ride, the bike I had crashed on (BSA) was still pretty mangled so I took the wing out for a quick jaunt. A short ride, but halfway through I began to feel unstable, weak and dizzy so I U-turned and headed home.
In my driveway I was maneuvering to park the thing when all of a sudden the world turned upside down. Vertigo. The bike ended up on it's left side in the grass with gasoline dribbling profusely onto my groin region. With pants soaked in gasoline I wrestled myself and my pinched ankle and thigh from under the bike. Walked away and tried to figure what the hell had just happened to me. Anyway I managed to upright the bike and get it parked, remove my soaked jeans and wash myself. I couldn't help but think later.. Man what could have happened if there had been a spark?


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