Possible vapour/air lock in fuel pump?

CruisnGrrl

CruisnGrrl

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For some reason my 91 750 vfr will not start. I last ran it 1.5 weeks ago when I was riding on the last weekend of july and I haven't gone anywhere where the stuff I was picking up would fit on the bike since (went on some track days with my other bike) so I haven't ridden it but it was running fine when I parked it.

I checked spark on the rear plug by pulling the plug and grounding it against the engine and it's sparking, when I pulled the plug it was dry but i could smell gas. air is pumping through the system because you can feel it when you put your hand over the exhaust hole. I checked the air box, nothing foreign in there, there is gas in the tank.

I can't remember if the fuel pump normally goes whirr when you first power up the bike but it's not going whirr now... I checked to see that fuel is getting to the pump and when I pulled the fuel line to the fuel pump it spews fuel no problems. i tried pulling the fuel line from the fuel pump and when I crank it spits out just a little bit of fuel. if i crank it long enough the bike goes woomph.

I've trailered my bike to toronto thinking that it was just a weak battery and I could probably charge it and get it going for the weekend (i've got some riding planned for friday, saturday & sunday).

I'm suspecting it's a fuel pump issue... is it possible that the fuel pump is air locked? that is something that happens on my ninja. if so how do I get it unlocked? I don't think it's the electrical to the pump because it's still spitting (not trickling) out some fuel.
 
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sounds like delivery or battery. Low battery is the most likely, with a slow drain. How old is the battery? Possible it won't hold charge anymore. Also check for poor terminal connections. I had an issue on my 08 CBR where the engine would crank fine but never fire, was just a semi-low battery. The next step is to ensure you have fuel pressure. Disconnect the fuel hose, put it in a bucket and prime the pump by turning on the key (don't start the bike). Plugged fuel filter, (not sure if it has any sensors on it), but that would be my next bet, i.e. kickstand sensor, bank angle sensor, etc.
 
smergy said:
sounds like delivery or battery. Low battery is the most likely, with a slow drain. How old is the battery? Possible it won't hold charge anymore. Also check for poor terminal connections. I had an issue on my 08 CBR where the engine would crank fine but never fire, was just a semi-low battery. The next step is to ensure you have fuel pressure. Disconnect the fuel hose, put it in a bucket and prime the pump by turning on the key (don't start the bike). Plugged fuel filter, (not sure if it has any sensors on it), but that would be my next bet, i.e. kickstand sensor, bank angle sensor, etc.
Click to expand...

I tried using a battery booster, i get spark but no ignition, i don't think the pump is priming.... research shows I can bypass the fuel pump for now.
 
So it pumps out a little bit of fuel when switched on?

Check the fuel filter ...
 
Brian P said:
So it pumps out a little bit of fuel when switched on?

Check the fuel filter ...
Click to expand...

when i disconnected the hose going into the fuel pump it was between the fuel filter and the fuel pump... fuel came out at a rate that had me scrambling to get the gas turned off and the hose back on the intake port of the fuel pump
 
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