The fuel pump on my 95 600 is not getting proper voltage. My voltmeter reads it is getting about 3 volts from the harness when the ignition button is pressed. I checked the ohm resistance on the wires going back to the relay, and they all seem fine. Does this sound like a bad relay cut off switch or cdi box?

A little background about the bike: The bike would sputter out after riding it for a short while. The bike stranded me at a stop light, and then I sat it for about 30 minutes and then it ran fine. I took the carbs apart and cleaned them out before discovering the electrical issue.

Any help is greatly appreciated.

 

That fuel pump is getting the voltage it's supposed to get. The problem is with your meter. The fuel pump receives pulses which are short in duration. Your meter is just averaging them together. A couple of sharp raps with your hand against the fuel pump would have probably gotten you back on the road a little sooner. The pump is known for having the contacts in it burn up. They're easily replacable.

 

The fuel pump works fine when I hook it directly to the battery. When hooked up to the harness, it does not put out any fuel. Could there be a pressure sensor or something I might have unhooked when I took out the carbs?

 

hey i just replaced the contacts on my fuel pump and now it works perfect. you should check the contacts by following dirts tutorial. even if u think they look a tiny bit like they need to bereplaced u should do it..

i learned the hard way 100 miles from home that when the contacts are bad... ur bike might as well have an empty tank lol. i waited for 2.5 hours for a buddy of mine to get there with a trailer to tow the bike it was terrible. as soon as i replaced the contacts my bike started first try

 

On a F3 if you get standard if possible by pass fuel pump and I heard it still will run just not the greatest.

 

Sounds like the issue has already been clarified, but this is not true. The fuel pump runs off 12 volts. It does not operate off pulse voltage.

 

If it runs off fuel pump relay like the 900RR (and I'm almost certain it does), it does get 12volts continuous run to it, but it's the relay that feeds it the 12volts. It only relays power when it gets signal from negative coil wire (blue/yellow, yellow/blue). If you aren't reading 12volts at pump with engine running (and pump works fine when you feed it direct 12volts) your relay is probably bad.

 

Just a sidenote...the pump doesn't run continuously when bike is running. When bowls are full, pump shuts off. I built my RR on a diet and discarded the fuel pump relay, it runs directly off ignition switch and have never had a problem with it (not counting a float that stuck on me).

 

A bad relay makes sense to me, or at least a good place to start eliminating variables. If anyone has an extra let me know and i'll buy it.

Thanks cbr900racer77

 

A sure fire way to tell is to wire a 12volt wire to hot wire of fuel pump with it installed on bike. If bike starts up and runs fine, it's almost certainly the relay. If pump is running fine and bike isn't running well, could be a short/break in negative coil lead running to relay. I realize it's a safety device to kill the pump in case bike goes down, but to me it's just something extra to go bad and ruin your day. I'm much happier without it. (That's just my personal opinion).
I'll see if I still have the relay off my 900 harness. I used Blackbird harness (well, a couple wires from it anyhow LOL) when I installed motor and they don't have fuel pumps or relays. If I can find it, it's yours for shipping but I doubt I still have it.

I'd also consider the other's advice on rebuilding fuel pump. Apparently it's a common problem and they'd have more experience with it. Better safe than sorry.