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Okay, so I have a 2005 GSXR1000 fuel pump not priming. Bench tested the fuel pump, it works. Next i took the fuel pump out of my 2005 GSXR 750 and it primed on the 1000. I’m so confused. It’s something to do with this pump for sure but i don’t understand, whats the difference between the 750 and the 1000 fuel pump??? The 1000’s fuel pump will work when 12v is directly applied but not when plugged into the bike. The 750’s fuel pump works fine plugged in. I’m lost
 

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Welcome.

That is strange. Are you putting power to the plug connector on the 1000 pump to test it or to the terminals at the base of the pump?
 

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The connector ought to have a Y/R, B/W, and R/B lead from the pump to the connector. Furthermore the B/W ought to connect to a stud on the pump's mounting flange. It ought to run if you put 12 V to the Y/R contact and connect a ground to the stud. If not measure the resistance from the Y/R contact to the stud. Also measure the resistance from the Y/R to the B/W contact.
 

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Discussion Starter #5
It does run when i connect it to a battery, however the GSXR1000’s fuel pump will not run connected to the bikes plug.
 

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Then it's either the Fuel fuse, the wiring, the fuel pump relay, or the ECM. First check the fuse. Then remove the fuel pump relay and check the voltage at the R/Bl and the O/W leads to its connector. Both should be 12 V. Reinstall the relay and check the voltage at the Y/R lead to the pump connector. It should go to 12 V for the duration of the priming, 1-2 seconds. If you know what you're doing, you could remove the relay and short the contacts for the R/Bl and Y/R leads. That should turn the pump on. Note that I don't have a K5 750 service manual and am basing this on a K5 1000 and a K6 600 manual. It might be the Signal fuse on yours.
 

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Then it's either the Fuel fuse, the wiring, the fuel pump relay, or the ECM. First check the fuse. Then remove the fuel pump relay and check the voltage at the R/Bl and the O/W leads to its connector. Both should be 12 V. Reinstall the relay and check the voltage at the Y/R lead to the pump connector. It should go to 12 V for the duration of the priming, 1-2 seconds. If you know what you're doing, you could remove the relay and short the contacts for the R/Bl and Y/R leads. That should turn the pump on. Note that I don't have a K5 750 service manual and am basing this on a K5 1000 and a K6 600 manual. It might be the Signal fuse on yours.
Note above that he plugged into the bike another pump off a 750 and it acts and runs normally so the bike side should be fine.

@Rubyjail Sorry, I'm out of ideas. Either you are missing something describing the symptoms or your testing is defective. These are not criticisms, just observations.
 

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Discussion Starter #8
trust me i wish
Note above that he plugged into the bike another pump off a 750 and it acts and runs normally so the bike side should be fine.

@Rubyjail Sorry, I'm out of ideas. Either you are missing something describing the symptoms or your testing is defective. These are not criticisms, just observations.
I’m just wondering if the K5 1000 fuel pump has some feedback it needs to give to the ecu for the ecu to allow it to turn on. That’s the only thing i can think of. The testing is pretty easy. I connected the wires to a battery, it started pumping fuel on my driveway. I install and plug the 750 pump in and the pump primes and the bike runs. The only thing i can think of like i said is if the fuel pump itself sends a signal to the ecu or something.
 

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If both pumps work with power applied directly but only one works when connected to the bike, how can it be anything but the connector on the failing pump? Sounds like something simple like a terminal on the pump connector may be loose or somehow faulty and is not making good contact when it is plugged in.
 

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The Y/R also provides power to the injectors. The ECM monitors that line but feedback from the pump is a bit of a stretch, i.e. it's more correctly feedback from the fuel pump relay. As said, you can override things at the relay. Also note that the tip-over sensor will prevent the ECM from powering the Y/R if it is on its side. Any chance that you've somehow got it involved? Were you testing one pump off the bike and another on? The pump motor is cooled by fuel passing through it so you shouldn't run it with no gas. It might be a faulty connector as HydeWhyte mentioned. That should be fairly obvious on inspection. It's a bit of a hassle but you could unplug the injectors, the relay and the ECM; then measure the resistance from the Y/R contact at the relay to ground.
 

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trust me i wish

I’m just wondering if the K5 1000 fuel pump has some feedback it needs to give to the ecu for the ecu to allow it to turn on. That’s the only thing i can think of.
Good thought and probably some cars have modules that do that but this pump is a simple permanent magnet DC motor. It's not sophisticated at all. Also, it gets it's power from the fuel pump relay and the relay is controlled by the ECM.
 

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Does the 1000 pump work plugged into the 750?

If so, would it be ok to just let them run in the “wrong” bikes or do they have different flow/pressure ratings? Dunno.


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