Fuel Pump does not shut off after a few seconds

Bike Rider

Bike Rider

Joined
Feb 14, 2016
Messages
16
Location
Ontario Canada
Bike
2003 ST1300 ABS
When I turn on the ignition for my 2003 ST1300 the fuel pump does not shut off after a few seconds like it does on my friends 2005 ST1300. It just keeps running as if it cannot pressurize the system properly.

Not sure if I should replace the fuel pump or pressure regulator etc.

Bike seems down on power at higher RPM and seems to have more hesitation than normal when rolling on the throttle plus pops/backfires? a lot when rolling off the throttle.

I can find lots of info on fuel pumps not working but nothing on them not shutting off.

Any help would be appreciated.

Thanks
Bike Rider
 
To me it appears that the pump cannot build the approx 50? PSI required and keeps trying. I woujld think a replacement, especially with other symptoms as you state.
 
Thanks everyone for the for the quick response.

Martin is the fuel pump relay also called the fuel cut off relay?

Bike Rider
 
The fuel pump is controlled by the ecm through a relay. Check the control side of the relay to see if it is still being commanded on. The system pressure has nothing to do with how long the fuel pump is turned on when first powering up the ignition. The fault is neither the pump nor the regulator. If the control side of relay is being turned off then look for welded contacts at relay. In that case then yes possibly pump is drawing too much current



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To expand a little further so everybody understands. On most EFI systems the pump is commanded to run for so many seconds at key on to restore any lost line pressure. The pump then shuts off until a certain oil pressure is observed at which point the pump is turned back on. Pressure is then controlled by the fuel pressure regulator creating a blockage in the fuel line. Kind of like putting your thumb on the end of a hose. The hose pressure goes up and water sprays with force out of the hose. In this case though the pressure is created in the line after the injectors. The regulator opens various amounts to hold line pressure as the injectors spray and bleed it off.

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mlheck said:
To expand a little further so everybody understands. On most EFI systems the pump is commanded to run for so many seconds at key on to restore any lost line pressure. The pump then shuts off until a certain oil pressure is observed at which point the pump is turned back on. Pressure is then controlled by the fuel pressure regulator creating a blockage in the fuel line. Kind of like putting your thumb on the end of a hose. The hose pressure goes up and water sprays with force out of the hose. In this case though the pressure is created in the line after the injectors. The regulator opens various amounts to hold line pressure as the injectors spray and bleed it off.

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Thanks Michael. I am a bit over my head on this one. To clarify are you saying that pressure regulator should be changed. I did check the fuel cut off relay and it appeared normal, is there another relay I should be checking?

That K1600 is a nice ride!

Bryce
 
gsforster said:
The fuel pump is controlled by the ecm through a relay. Check the control side of the relay to see if it is still being commanded on. The system pressure has nothing to do with how long the fuel pump is turned on when first powering up the ignition. The fault is neither the pump nor the regulator. If the control side of relay is being turned off then look for welded contacts at relay. In that case then yes possibly pump is drawing too much current



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Click to expand...
Thanks for the info. I am over my skill set on this one is there another relay I should be checking because the I pulled the fual cutoff realy and it looked fine.

Bryce
 
Try this once. Turn the kill switch off, then turn the key on. Now toggle the kill switch to run and then back off again. Each time you flip it to run you show hear the relay click and the fuel pump run. When you shut the kill switch off, you should a softer click and the pump should shut off. If the pump continues to run then your relay is sticking on. If it is sticking on the contacts may be corroded or burnt. If they are then you may not be getting the full 12V to the pump, which will keep the pump from running at it's full volume.

On my '05 the pump runs for 2.5 seconds total after flipping on the kill switch.

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Last edited:
Sorry for the delay in responding I am teaching a Motorcycle course this weekend.

I have not changed the fuel cut relay with another relay but I did just go out and turned the key on with the kill switch off. When I turned the kill switch on I did hear the relay click, the fuel pump came on and much to my surprise shut off after about 3 seconds. I flipped the kill switch off and on a few time and each time the pump came on and shut off after a few seconds.

I then turned the key off and turn the kill switch on and and then turned the key on with the kill switch on a lo and behold I heard the relay click the pump came one and shut off after a few seconds. When I turned the key off I did hear a softer click. I repeated about 3 time with the same results.

Not sure if using the kill switch method some how unstuck the relay but it seems to be working fine now. could it be a weak relay and I should just replace it to be on the safe side?

Again thanks so much to everyone for their help!

Bryce aka Bike rider
 
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