Fuel Pump Not Priming / Starting & Running Problems

[Blackboar19]

Need help sorting out a fuel pump issue.

Found and replaced a dirty fuel filter in November.  Bike ran fine afterwards.
A week ago, when you turn the key the fuel pump does not prime, but you can hear the relay click.  I get power to the harness at the fuel pump.  I take apart the pump, cannot find any bad wires, jump power straight to the pump and it turns over.  I realize that I'm running the original batter on an 05 620, so I put in a new battery and the pump primed, and the bike started right up.

Next time I ride it cuts out after 40 minutes, now doing the same thing:  no prime, no start.  Gauges sweep, relay clicks and you can measure power at the fuel pump harness.  Troubleshooting leads me to believe the pump has failed.  (put on Ted's (artful's) tank and bike started right up, ran up to temperature)
I replaced the fuel pump via CA-Cycleworks and at first got the same result.  Took the pump apart and put it back together and the bike primed and started right up and got me home from Ted's, about a 30 minute ride.  This morning on my way to work, bike cut out again, now same thing, no prime, no start.

I checked the charging system when the bike was running and it checks out OK, 14.47 volts.

I'm going to hunt for a bad wire (even though that has already been done once) but otherwise I'm:
Stumped, please help!

Thanks,
Matt

[uberranger]

I have a similar problem to this, but acquired by different means. 

I bought a salvage bike that ran fine, the took it apart to have the motor mount welded.  When I
put it back together, this happened.  I put the key in, turn it on, and immediately a clicking starts
(fairly rapid, not too loud) and, after lifting the tank up and listening, have determined it to be
coming from the fuel pump itself.  Unplugging the fuel pump confirms this.  I thought maybe I had
hooked the fuel lines up backwards when I put the tank back on, but reversing them didn't help. 

If there is anything that I can cross-check to help find the cause of the problem, please let me know. 

Also, if you are having a completely different problem and I'm just junking up your thread, let me know 

[Blackboar19]

Uberranger, the problem you had is different.
Thanks though!

[uberranger]

Okay, good thing I checked then! 

Good luck

[ducpainter]

There have been a few threads about the wiring failing inside the sending units.

[Blackboar19]

so here's my stupid question:  what exactly is the sending unit?  I've read some of these threads and didn't catch exactly how to check it out.

Is it the device that mounts on the flange at the fuel inlet?  If not, what the heck is this thing?  This has only the black wire running to it, coming from the plug for the fuel pump motor.  I don't know what this is.  I know what everything else is, there's a resistor to signal low fuel, the pump, the filter, and this little device at the inlet?

What is this device's purpose?  My tech guide does not really break the fuel pump completely down.

[Howie]

The sending unit is the part that triggers the low fuel light when the tank is low.  What year is your bike?  Plastic or steel tank?

[Blackboar19]

2005, plastic tank.

[Speeddog]

2005, plastic tank.

Sending unit is not sold seperately from the fuel pump/flange assembly.

[Blackboar19]

Thanks for the info Speeddog, the manual does not list the part number for this and it looks like you might be associated with a dealer, do you know the part number?  Does the flange include the pump motor, because I'd kind of hate to buy two in a week....

There is a part number listed for the thermistor, with the black and white wire going to it.  I've been trying to find out what ohm reading I should get on this and can't find it on any of the other posts.  Any detailed advice on how to test this out and figure out exactly what to buy would be great.

Thanks again everyone for you help.  I hope to have this sorted out soon, I haven't had a reliable bike since November and at this point I'm really ready to hit some twisties!
Matt

[Blackboar19]

http://www.flickr.com/photos/80693452@N07/?uploaded=1&magic_cookie=3cf265f9aca4da88b79a8c07604e8ab8

This is the part with the black wire running to it that I describe in the original post.  Ducpainter tells me he thinks it is the pressure regulator and not the problem....

Just trying to get a better understanding of the overall system and the components.  Thanks!

[Speeddog]

The parts catalogue shows it as 160.2.135.1A Flange, includes pump, filter, thermistor, everything.

Downside is it's *extremely* expensive, ~$1k.

[Speeddog]

Fixed your pic:


Pump Component by Blackboar19, on Flickr

[Blackboar19]

Can anyone tell me how many Ohm's I should be reading across the thermistor?  I'm getting 3.3.

I also think I'm finding a bad wire connection inside the plug to the pump motor, I'm going to fix that up and see what happens.  I'm getting intermittent continuity when I test the black wire, and the culprit seems to be the plug.  I'll keep you all posted, and thanks again for the help.

[Blackboar19]

UPDATE:  FIXED !! 

It was NOT the sending unit (thermistor) as thought.  It turns out that the black wire running to the pump motor was broken right at the potting passing through the flange.  The insulation was totally intact but the wire inside was broken.  This is the wire which was in question but kept giving me good continuity, so the last time I rebuilt the pump it was making contact, but on the ride would come loose.  I took a friends advice, cut the wire on both sides, drilled a hole through the potting and pulled a new wire sealing it up with some JB Weld.  I also replaced the harness on the pump so that I only had one splice at the harness OUTSIDE the tank.

Since nobody can tell me the resistance on the thermistor, I'm going to go with my reading of 3.3 ohms and say that is normal.