I think they are set up to shut off when a certain pressure exists in the system and cycle back on when the pressure drops below a certain point. Other wise pressure would continue to build with the pump runnimg continuously and pump raw fuel straight into the intake tracts. My ZZR 12 does not have external fuel pump relays, so either they are contained in the pump bodies or are inside the ECU. My guess is within the ECU since they have 4-wire connectors where most Kaws seem to have 2-wire connectors and external relays. Possibly a voltage spike when the pressure rises triggers the relays to shut off power to the pumps and signals the pumps to function when the pressure drops below a certain figure. I'm really just guessing, but this makes sense to me. Having the pump "hard wired" should not matter as long as you shut the switch off when the key is turned off and didn't bypass the relay. Again, just guessing.

 

I bypassed a bad fuel pump relay on my 99 zx7r this summer and wirred the pump to ignition wire, bike runs great. easy way to tell, turn on fuel run pump, pump should shut down when pressure is reached, turn off fuel run bike a few seconds shut off, pump should continue to run, i would guess your problem sounds carb related.

 

In a carbureted bike, the fuel pump doesn't "know"....it pumps any time the starter button is depressed or when the engine is running. The fuel pump relay is bypassed by the starter button or the relay is powered to close with the same signal as the ignition coils.

However, the fuel pump only makes 2-3 psi of pressure....not enough to overcome the shut off valves in the float bowls. Its a solenoid style pump....so when it encounters enough restriction it won't cycle...even though it is still being powered.

 

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John nailed it as usual.

The pump is ran off the CDI box by a trigger wire....anytime the bike's ignition rotor is spinning then the fuel pump is pumping .
the pump kicks in as soon as the starter switch is pressed and continues to run as the bike runs...the fuel pump is there to overcome the pressure of the design at faster speeds ...wiring it into a hot wire does nothing but strains the pump until the bikes running as its being forced to build pressure and will probably eventually kill the pump..

Hope that helps

eh. sorta. it runs off the #1/4 coil pack signal. theres no dedicated pump output.

 

Im Having the same prob with my bike "95 zxr750" I just bought it and its haveing alot of the same probs... I'm guessing its the fuel pump and not the carbs, only because mine are new and tuned, and the dude that i bought the bike from rigged everything on the bike and i cant figure the pump out, It ran fine for maybe the first mile, and it shut off and wouldnt start, checked the battery and it was a little low, so i put it on the charger, the next day it ran fine again then it did the same thing, it just died. I pulled the tank and undid the pump, and when when i picked it up it leaked fuel every were, and the bike was still on, I think it was hard wired, cuz i fund the relay unpluged and tossed aside.... Im going to the shop I think, unless some knows what to do. "BIG MESS"

 

The pump is ran off the CDI box by a trigger wire....anytime the bike's ignition rotor is spinning then the fuel pump is pumping .
the pump kicks in as soon as the starter switch is pressed and continues to run as the bike runs...the fuel pump is there to overcome the pressure of the design at faster speeds ...wiring it into a hot wire does nothing but strains the pump until the bikes running as its being forced to build pressure and will probably eventually kill the pump..

Hope that helps

 

yes my name is steven and i need sum help i was riding my 1992 zx750 ninja home the other night and it started acting up when i would give it some throtle it would bog down like it was running outa gas so i couldnt hardly get my bike home the only way my bike would go was to use the choke as a throttle so it was a long slow ride for about 3 miles when i got home i tore the bike down checked my plugs there fine carbs were fine but im not sure bout the fuel pump how many psi is the fuel pump suposed to have and is it suposed to run all the time or just when i hit the start button on the bike will someone please help me thanks alot

 

kinked fuel line!

 

how did you wire the bypass of the fuel pump,having same problem with zx7 95,help really needed

 

My fuel pump runs untill i hit the start button then it turns off what could be my problem?
92 zx-7

 

probably the fuel pump relay.. BUT i'm not going to say that for sure..
the pump should switch off the starter control power circuit to the ingition circuit for the cyl. 1/4 coil once the bike starts and you let off the starter button.

does the bike run at all?

 

Engine shuts off (intermittant problem)

I have a 1993 Ninja ZX7 (stock no modifications).
I was riding when all a sudden the engine just shut off. I tried to restart it under compresion but no luck. I stopped on the side if the road and tried to restart the bike with the starter switch, but no luck. After a couple of tries it started up. While I was riding home, I noticed that the rpm's was erratic when I was stopped at a light. It's hapend a couple times since then.

I've removed the tank and verified the wires. I found 1 burnt connection and 1 loose connection. I repaired them but I still have the problem.
I,m thinking it's a problem with the fuel pump?
Can the fuel pump cause this problem?
How to check the fuel pump?
What else can cause the problem?
:banghead

 

I have a 1993 Ninja ZX7 (stock no modifications).
I was riding when all a sudden the engine just shut off. I tried to restart it under compresion but no luck. I stopped on the side if the road and tried to restart the bike with the starter switch, but no luck. After a couple of tries it started up. While I was riding home, I noticed that the rpm's was erratic when I was stopped at a light. It's hapend a couple times since then.

I've removed the tank and verified the wires. I found 1 burnt connection and 1 loose connection. I repaired them but I still have the problem.
I,m thinking it's a problem with the fuel pump?
Can the fuel pump cause this problem?
How to check the fuel pump?
What else can cause the problem?
:banghead

you posted a thread. i answered