14 YZ450F fuel pump leaking/diagnosis

[GHILL28]

I've been chasing an intermittent starting issue with my '14.  I have it narrowed down to a couple things.  While trying to run a fuel pressure test by splicing into the fuel line at the fuel pump, I noticed that the fuel pump seemed to "dribble", which isn't what it's supposed to do.  I'm not able to source a quick-disconnect fitting to make a fuel pressure adapter for my test, so I just took the pump out to inspect it.  No sign of a breached line or anything inside of it, but when I blow air into the outlet with about 40-50psi, it comes right out at the top of the brown 30mm diameter pump.  The pump itself whirrs just fine with 9V applied to the leads.

 

Assuming it's at the o-ring seal at the top of the brown part in this picture.  This is not normal behavior, correct?  

 

 

 

In the meantime I'm going to see if I can still find a way to rig this up for a pressure test.  The good news is that these fuel pumps now have a superceding part number from Yamaha and are only $250 instead of $400.  But I'd still rather just replace an o-ring if that's all it needs.

 

 

The other odd thing I found was that when using a spark tester (lighted one), it would only light up every 4 kicks or so.  So I may have more than one thing going on here.  I suspect it's the capacitor, again.  Apparently these things are known for going out with some regularity.

 

 

Edit, this is not a picture of mine.  I don't have it apart right now.  I only took it apart once about 35 hours ago to clean the filter.  Also, what is that cylindrical piece just above the filter?

Edited January 15, 2017 by GHILL28

[Trenton Dixon]

Aye man same thing has happened on my 2020yz450f, the fuel pump it drips a drop about once a day, just small drip and I'm thinking it's the fuel pump seal cause I don't see any where else its coming from?

[jimmy bush]

Working on a 2013 CRF 450 R that wont run. When I took the fuel line off the spigot on the bottom of the fuel pump, gas flowed out. Is that normal?