Fuel pump not working

[rcassin]

Hi All, please let me throw this out to you again. RTP 1100 2000.

Relay good, fuse good, side stand switch good. It cracks but the 2 second pump does not come on. I jump the pump relay and the pump works. Has this happened to any of you ? and what did you do? or does anyone have a clue what is wrong? Thanks, Rob

[dirtrider]

Afternoon Rob

 

One check is to see if you have 12v to the fuel injectors (green wire) at first key on (for 2 seconds) then during engine cranking. That will tell you if the Motronic has closed the fuel pump relay contacts & is sending power to the pump circuit.

 

Your fuel pump circuit is actually two circuits-- at key on 12v flows from the ignition switch, to the kill switch, then to the side stand switch, then to one side of the fuel pump relay pull-in coil. The other side of the fuel pump relay pull-in coil is pulled to ground inside the Motronic to initiate the fuel pump relay. (the Motronic pulls the pull-in coil circuit to ground for 2 seconds at key on, the Motronic then full time grounds it during engine cranking & engine running)

 

For the fuel pump relay to send 12v power to the fuel pump it needs to get 12v power form fuse #6. Once the relay contacts close it then sends that 12v power to the fuel pump & fuel injectors.

 

One thing that can effect the fuel pump relay turning on is a bad HES (crankshaft sensor) & that is under the front lower engine pulley. It's actually not the sensor itself but bad insulation on the wires coming from the HES just above the sensor.

 

So see if your green wires at the fuel injectors have 12v at first key on & during engine cranking.

 

[rcassin]

Hi DR...What would I do with out you??? Nothing going on at the injector wires! Thanks again, Rob

[dirtrider]

Evening Rob

 

Have you also checked fuse #5 (Moronic fuse)?

[rcassin]

Hi Dr...Sorry maybe I was not clear... I am getting no VOLTs out of the injectors! Thanks, Rob

[dirtrider]

Hi Dr...Sorry maybe I was not clear... I am getting no VOLTs out of the injectors! Thanks, Rob

 

Evening Rob

 

The fuel injector green wires get their power from the fuel pump relay, the fuel pump relay gets turned on by the Motronic, the Motronic gets it's main power from fuse #5. If fuse #5 is open the Motronic won't be able to turn the fuel pump relay on.

[rcassin]

I will recheck that fuse... But they all looked good to me and a did test the fuel pump fuse. If they fuse is good, then what? Thanks, Rob

Edited November 18, 2016 by rcassin

[dave_a]

Swap your horn relay with your fuel pump relay (they're identical)and next to each other in the fuse box.

If your problem disappears... buy a new relay.

[rcassin]

Hey DR... I feel like a total jerk... Check fuse 5.. MIA, MISSING!!!PUT A FUSE IN, AND SHE FIRED RIGHT UP!!!How can it run with no fuse? I really appreciate your help! Rob

[rcassin]

Thanks, I have tried that and tested the original relay. Relay is good, Rob