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Bad Fuel Pump (but not really)

  #1  
Old 06-19-2016, 02:50 PM
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Default Bad Fuel Pump (but not really)

Last weekend I changed the oil on our bikes in preparation for our 2 week bike trip. Anyway, after changing the oil in my wife's bike, it wouldn't start. Turned over just fine, but not start. I could not hear the fuel pump priming. I operated the Engine Stop switch on the right hand grip and I could hear a relay in the back right tail section clicking on and off. All normal sounds.

So I got out a meter, checked the wiring diagram and made a couple of checks. I was getting 12v out of the Brown wire of the Fuel Cut relay. I then checked for that same 12v at the 3 pin connector under the fuel tank. I had the 12v there as well. I then checked for continuity across the Brown wire to the Green wire and it was open. I compared to my other F4i and found it had 1.4 ohms. Clearly an open circuit. So, I ordered a replacement pump from PartZilla. It came in, I installed it and it worked fine.

Normally that would have been the end of it, but I was curious what exactly was wrong with the old one. I put my meter across the pins of the connector that is located directly on the pump. This would be a connector that is inside the tank when it's installed and not accessible unless you remove the pump from the tank. Amazing enough it showed continuity!. I attached my 12v supply to the 2 pins of the fuel pump and it ran just fine, the pump itself was good. So I started tracing the wiring figuring that one of the pins on the wiring harness was bad or loose. It turns out that the connection where the wiring passes through from inside the tank to the outside is where it's broken. There is a ceramic piece where the wiring passes through from inside to outside and there is epoxy around the wiring to keep them sealed. The wire inside is Blue, but on the outside where it plugs into your bikes harness is Brown It's inside this area where the break is located. The ceramic piece is not something that is replacable.

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I had been tempted to order just a replacement pump off of ebay because the fuel pump from Honda is stupidly expensive. I'm glad that I didn't go that route. Replacing just the pump would not have fixed my problem. I'm sure that this is a rare instance. I can't imagine this happening on a regular basis. Anyway, I thought I'd pass along what I learned. If you're thinking of replacing just the pump itself, make sure you take the old one out first and test it to make sure it's actually bad.
 
  #2  
Old 06-19-2016, 07:35 PM
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That is a strange place for a failure...
Nice work being thorough in your diagnostics.

Good to see you around again too!
 
  #3  
Old 06-19-2016, 10:35 PM
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Originally Posted by 74demon View Post

Good to see you around again too!
Thanks, it seems like I'm finally starting to be able to come up for air again.
 
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