I have a 1987 600 was running fine for the first couple weeks of the riding season until one day it started stalling at idle. It doesn't happen every time its idling mostly when its warmed up fully. I notice that when this happens my fuel filter is about half empty or half full however you want to think of it. I did the pump flow test by jumping the relay and it flows plenty of fuel. I noticed that when the bike it running there is a surging or pulsing in the fuel line, you can also see it in the filter if there is a bubble in it. Does anyone know if this is normal? It happens very randomly some times it happens consistently and sometimes there is a few seconds in between pulses. I hooked a lab scope up to it and found that when it happens the control circuit from the fuel pump relay to the pump drops to 0 volts for anywhere from 10ms to 60ms. I checked the signal to the relay from the computer which also runs one of the coils and that signal looked fine. To me it looks like a relay issue so I put a relay in it but the problem is still happening. Sorry for such a long post. Any input would be much appreciated. Thank you.

 

Sounds normal. There is an idle adjustment... the black plastic **** at the right end of the carbs.

 

I have the idle adjusted to what it says on the sticker on the bike. Its set at about 1200 rpm. I just took it out for about a 10 mile ride and the pulsing in the line doesn't seem to be there anymore and it did not stall at all. When I got back I noticed that the fuel pump doesn't always run. If I put my finger on it I can feel it pumping and sometimes it stops. Do you know if this is normal? I don't know if maybe it stops when it builds up some pressure in the line to the carbs. Also the fuel pump seems to be very hot to the touch I also don't know how normal this is. Thank You for your input.

 

It is normal for the fuel pump not to run all the time. It is not meant to run all the time. Perhaps you had some air in your fuel line, who knows? As far as it being hot, not too sure about that , but everything in that area usually gets hot due to engine heat.