Hello!

I thought I'd introduce myself; I am a long-time motorcycle rider and have several bikes in the garage. They range from a 1946 Norton Model 18, 500 single, to a 1960 BMW R60/2, a 1980 Ducati Pantah and a 1985 Yamaha FJ1100. I try and go on a summer, week-long, trip around BC and was looking for a six-speed, water-cooled sports/tourer to replace the FJ1100.

I knew a friend had a Honda CBR1000F in his garage with low kilometers and after a few months of asking I was finally able to buy the bike. It is in very nice shape, with just 2,450km on the clock. It needed all the usual parts after a long sleep; I replaced the battery and rebuilt the carbs, replacing the needle and seat assemblies and the o ring in the bowls.

I wondered if I could draw on the wisdom of the forum and ask a couple of questions? When I turn on the ignition I hear nothing from the fuel pump. Is this correct? I'd expect a click or a whine at the very least, but I could be wrong. I think the previous owner thought the same thing; he bought, and never fitted, a new pump relay. Swapping the relays did not change anything, however if I shorted the red/black and black wires at the relay plug, the pump bursts into life with a satisfying sucking sound. It sounds very healthy so I am going to assume the pump is fine, its just not coming on when the ignition is switched on. Is there anything I need to check (fuse? plug?) to resolve this, or is this normal?

I have a gas leak from carb 2, but hopefully will be able to fix this. I did have the bike running when I plugged the fuel delivery line into the carb fuel rail and bypassing the pump, it sounded very sweet! Having said that this time, with the fuel pump plugged directly into the carbs to bike failed to start.

So... is there anything special I need to do to the pump? Prime or purge it perhaps?

Many thanks in advance for any advice and assistance.

Andy

 

So my bike electric-savvy buddy Jamie had a look at the Hurricane wiring today.

After some serious digging and testing he came to the conclusion that the diode in the fuel pump relay circuit had failed. The upshot is that the failed diode was no longer isolating the relay, and a back feed voltage of about 5 volts was enough to prevent the relay from closing and thereby energizing the fuel pump. No closure meant no power, meant no pump.

Complicating matters was the fact that we also believe the relay itself had failed... We ended up installing a new, five pin, automotive relay that was good for 30amps. We ran a dedicated ground line from the relay to the nearby frame connection and now, when the ignition is turned on, the fuel pump runs. I am going to carry a spare relay in my toolkit in case this set up gives a problem.

As far as I could see you can have a functioning fuel pump and fuel pump relay and if the diode fails it looks like one or both of these items could be faulty, when in fact they are fine. We believe that the faulty diode is inside the ignition module, although we might be wrong and there are probably others on the forum that can point us to its actual location. We debated opening up the ignition module to see if we could find and replace the diode, but in the end simply decided to fit a new relay and run a dedicated ground, rather than having access to ground being influenced by the diode.

I hope this helps someone with similar fuel delivery symptoms, tomorrow I am going to see if the bike starts and runs, with the fuel pump now part of the system.

 

My understanding is for the 1988, the fuel pump is pulsed - it's not on continuously. They dropped the pump entirely for the later models.

 

Thanks for this Rockpool. I wondered whether you could do away with the fuel pump completely, your comment seems to confirm it was not essential. The bike seemed happy to run when I bypassed the pump, and the ID of the fuel hose seemed large enough that I couldn't see the motor starving for fuel, even when travelling fast. My 1985 Yamaha FJ1100 has similar diameter fuel hose and doesn't need a fuel pump.

Today is going to be a test, as I am tidying everything up and will see if I can get the bike to run with the fuel pump as part of the system.