So Ive read a lot of threads about the fuel pump, fuel cut-off relay (3p) and fuel pump power relay (5p). I have been having trouble getting fuel to my 99 f4. The fuel pump does indeed pulse when hooked directly to 12v (via jumper from bl/w at fuel cut relay to pump) replaced the fuel transfer (or power relay) after running through tests outlined in service manual. When testing after the replacement I am getting 12v while ignition on by bike off at both the bl/bu and bl/w on the fuel cut relay. After manually priming the carbs and starting the bike I am getting 9.8 at the bl/white wires at both relays, 8.5 at bl/yellow (connects both relays), and 8.5 at bl/blu at the fuel transfer relay.
So my understanding is that the bl/white wires (which are evidently power from the ignition cut-off switch) are feeding both relays, but this switches from the bl/y (0 when ignition off).
So we used a 4 pole relay and a jumper that basically bypassed both the fuel cut-off and the power relay and sent 12v directly to the pump while still allowing for a switching mechanism (ie a relay) and got the faithful heartbeat of a reliable pump.
All this being said - DOES ANYONE KNOW HOW TO TEST THE FUEL CUTOFF RELAY RELIABLY? DOES ANYONE KNOW THE CORRECT VOLTAGE THAT I AM SUPPOSED TO GET FROM THE BL/Y WIRE AND THE BL/BU WIRES OR HOW THE TWO RELAYS WORK IN CONJUNCTION WITH EACHOTHER?
Your Friendly Newbie - CatDaddy

 

One more thing.

WOULD BYPASSING BOTH AND SPLICING THE IGNITION INTO A MODIFIED 4P RELAY HAVE ADVERSE EFFECTS ON MY BIKE?

 

some interesting stuff on relays - not sure if applicable -
http://www.autoshop101.com/forms/hweb2.pdf

 

I had the same problem last year. I ended up replacing the fuel cut off relay. I don't remember all the voltages, but I remember the output voltages from the fuel cut relay being under 10v. My pump wasn't kicking on at all.

 

yeah, Ive pretty much narrowed it to the cut-off relay. The interesting thing is that relay doesnt necessarily just swith a +/- signal but allows a variable rate of voltage from the coil (???) and the ICM to be modulated before it hits the other relay. By jumpering a 3P relay directly to a ground (instead of that variable voltage wire bl/blu) I was able to get the pump to act right!! Thanks for the advice. Ordering tomorrow. <

 

I'm still having problems with my voltage on the rest of the bike. Not enough core voltage coming from the rectifier even after getting a new one. I was doing some reading last night and found a new style rectifier/regulator that uses a mosfet chip - all the guys using it are getting ~14 volts at idle - this is going to be one of the first things I order on my next paycheck. I'm barely getting 12.5v at idle.

 

Your not supposed to get that much at idle. The bike is designed to put full charging power at 5-6k rpm. That's why its not good to put around town nor stay in a high gear to keep rpm down. The battery wont stay consistantly charged and will fail.

 

The issue isn't that it's not supposed to, the issue is that the stock rectifier sucks. The new 07+ rectifiers use a mosfet chip in them that is way more effecient and runs cooler. This allows it to regulate the charging system much much better and actually keep the battery charge even at low rpms. This is the issue I'm having with my bike - if I sit idle to long the bike stutters and doesn't want to run. But if I hook the bike up to a car that is running (via jumper cables) and its getting good voltage it doesn't have any problems at all even if I let it idle for 15-20 minutes.

 

Please tell me thats a misprint? Is the car running or not? If you hook any motorcycle up to a running car that is putting out a minimum of 65amps(normally closer to 100+) you will fry all electrical components on the bike. The stock rectifiers may not have been the greatest but they generally work fine if the rest of the electrical system is maintained properly. It's quite common however that the battery's get weak over time and are overlooked till they have caused unnecessary wear and tear on the rest of the electrical system.

 

What?? The car isn't going to "FORCE" power into my bike, that's not how power works and the bike isn't going to pull any more power from my running car than it needs to. Plus, it's only hooked up to a honda civic with a 60amp alternator. My issue is that my voltage at the battery on the bike is about 12.5 when the bike is off and at idle it's even lower than that with the bike on. I put a new rectifier on last year and it worked ok for a while until it started getting really hot 90+ degrees outside, then it started failing again cause it was running too hot and not efficiently charging the battery - after 20 minutes of riding the bike wouldn't idle at stop lights. Hooked it up to a good power source (aka honda civic) and it idles fine. That's why I'm going to do the rectifier conversion this year and see if that solves my power issue. I'm also going to replace the battery at the same time.