1 Fuel injector voltage confusion Tue Jun 02, 2020 12:25 pm
Tattooist Keith
active member
First post so apologies if it's not in the right place.
I have a 1990 k100rs cafe racer project on the go and I've recently put everything back together after removing the abs. I have kept all of the original electrical components (relays, sensors etc) but I have shortened some parts of the loom where there was excess lengths of wire. Bike started up first time every time before I started the project.
I've now got everything back together but can't seem to get it to start. It's turning the starter motor, pressurising the fuel rail, I can hear the fuel pump prime, relays click, neutral light, sidestand switch, all good. But doesn't fire. I've checked the injectors on the bench by manually applying 12v and they all spray perfectly. So I've then checked the injector plugs. When testing with a multimeter, I get 12v on one pin and earth on the other when they are ALL unplugged and the starter button is pressed. But when I plug any one of them in and check the other 3, I get 12v at both pins, no earth. Now I don't know if this is normal as I know they should pulse, or whether it points to an issue somewhere, maybe the ECU? I've pulled the fuel rail out with all the injectors and plugs still connected pressed the starter to see if the injectors spray, which they don't. So there's obviously an issue, but I'm not sure what it is. Any input from you brain boxes and k100 geniuses is much appreciated. Hopefully I've provided enough information, if not, let me know what you want me to check/look for/explain further.
Ride safe
I have a 1990 k100rs cafe racer project on the go and I've recently put everything back together after removing the abs. I have kept all of the original electrical components (relays, sensors etc) but I have shortened some parts of the loom where there was excess lengths of wire. Bike started up first time every time before I started the project.
I've now got everything back together but can't seem to get it to start. It's turning the starter motor, pressurising the fuel rail, I can hear the fuel pump prime, relays click, neutral light, sidestand switch, all good. But doesn't fire. I've checked the injectors on the bench by manually applying 12v and they all spray perfectly. So I've then checked the injector plugs. When testing with a multimeter, I get 12v on one pin and earth on the other when they are ALL unplugged and the starter button is pressed. But when I plug any one of them in and check the other 3, I get 12v at both pins, no earth. Now I don't know if this is normal as I know they should pulse, or whether it points to an issue somewhere, maybe the ECU? I've pulled the fuel rail out with all the injectors and plugs still connected pressed the starter to see if the injectors spray, which they don't. So there's obviously an issue, but I'm not sure what it is. Any input from you brain boxes and k100 geniuses is much appreciated. Hopefully I've provided enough information, if not, let me know what you want me to check/look for/explain further.
Ride safe