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Discussion Starter · #1 ·
So after riding the bike for a while and turn it off pump won’t prime just makes a knock sound like it’s seized up but after it cools down it works again!!! Even if the bike just sits out in the sun for a while same thing. Put it in the shade for a while it cools down pump primes again!!… any suggestions???
 

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The only course of action I can suggest is to troubleshoot the circuit under the conditions in which it is failing. If you look at the schematic diagram for the fuel system circuit there are several components in the control circuit to start the pump. Trace the voltage through the circuit to see which component is failing. If there is voltage at the pump connector then your fuel pump is likely on its way out. The service manual is your friend.
 

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There are two relays in series with the pump. The first is the bank angle sensor relay, next is the fuel cut relay. With the key on, you should have voltage on both sides of the relay contacts. Check the bank angle sensor relay first since it must be picked up in order for the fuel cut relay to get voltage to the pump. If either relay is not picked up, then you can test the relays by removing them and applying battery voltage to the coils and check for continuity across the contacts. If either relay does not pick up, you’ve found your problem. If both relays are good, then you will need to get a service manual and work your way through the fuel system circuit to find your issue.
 

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If the relays are good then you will need to go through the troubleshooting steps in the service manual to diagnose where the problem lies. There are multiple possibilities in the fuel system control circuit which can cause your issue. The only course of action is to work your way through and eliminate them one at a time. The fact that your problem is intermittent and only appears under specific circumstances will make it more difficult.
I had an issue with my bike where as I was riding it would suddenly lose power momentarily and then come back on as if nothing was wrong. This happened a couple of times on consecutive rides. I had changed the battery so I knew that was not the problem. I finally took the time to check the electrical connections one at a time. I used a contact burnishing tool and cleaned the connections and made sure they were all clean and properly made up. So far I have not had the problem resurface. Electrical gremlins can be frustrating and tedious to find. Good luck.
 
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