'99 748s fuel pump won't run w/troubleshooting so far.
Hello all. I've tried to do as much research and searching before posting as I can. I've been troubleshooting a weird issue with my fuel pump not running.
1999 748s (Yellow, the correct color...lol.)
I have taken the following steps:
1. Tested fuel pump off bike (still in tank,) with 12v battery - good.
2. Tested for 12v at wiring harness - good (I get 12v for ~1sec, then 12v during cranking.)
3. I've tested the fuses at the fuse box and the 2 on the tail of the bike - good
4. I've jumped the bike side of the plug to the tank side of the plug with test wires - FAIL (Wanted to make sure it wasn't the plug itself.)
5. I've connected the - side of the tank plug to the - side of the bike harness with a jumper, then connected the + side of the pump plug to the battery of the bike - good
6. I can hear and feel the relay under the tail clicking on and off for 1sec at key ignition turn on.
It's bizarre to me that the pump is good, the 12v at the bike side harness appears to be good, but I can't get the pump to run when connected via the plug or when jumped through the plug with test wires. Yet, when I jump the - side of the harness / plug and connect the pump directly the battery it runs. It just doesn't make sense.
Could I have fried the relay so that it's OK without load, but when it's getting a load put on it it's failing? If so, is there a place to get a reasonable replacement other than going to the stealership? It looks to just be a Bosch relay right?
'99 748s | '06 FJR 1300 | '92 GS500e project
Last edited by JayRodRay; May 2nd, 2017 at 8:37 pm.