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Author Topic: When does the fuel pump actually run, and what triggers the relay?  (Read 8770 times)

Offline jakgieger

  • itinerant farmer
  • ^ SuperNatural Motobricker
  • Posts: 618
When does the fuel pump actually run, and what triggers the relay?
« on: July 28, 2015, 03:02:07 PM »
Sooo...Years ago I bought a box of parts (R60/5) and completely restored it.  Then marriage and kids intervened...Now that I am having a "mid life" crisis :hehehe, my wife has allowed me to buy my dream bike, a 1989 k100 rs.  Another barn find/basket case.  But the technology seriously changed from 1971 to 1989.  First question, when does the fuel pump actually run?  2, What triggers (wire color) the fuel pump relay? and   3, I found an injector set on ebay....http://www.ebay.com/itm/201388267293?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT.  I purchased the set as I am having to completely renew the fuel system (previous owner left gas in the tank for 15 yrs).  Has anyone changed the injectors in their bike, and did it work ok?  My backyard buddy mechanic thought it was a good idea...
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline johnny

  • TrailBrakingThrottleWhacker
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  • Whacking...n...Chopping Sliding...n...High Siding
Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #1 on: July 28, 2015, 03:54:19 PM »
greetings jackgeiger...

welcome to motobrick.com...

your wife oughtta getts her head examined... cause thats whack... whack whack whack whack whack...

j o

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  • :johnny i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin  :johnny

Offline jakgieger

  • itinerant farmer
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Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #2 on: July 28, 2015, 07:45:51 PM »
Well, that wife is a one in a million.  Incidentally, the reason she married me was that I showed up for our first date on my R bike.  Her dad used to take her to school on an R70/5.  Our first year of marriage, I drove the bike 60 miles a day to work.  Coming home one night I hit a German Sheppard at 45 mph.  I was doing 70 when I saw the dog (damn drum brakes).  I rode it out, but went home and told her...just a case of bad timing.  Anyway her dad's R bike is still around and I hope to own it one day...Any help with the original questions? Thanks
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline rbm

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  • Posts: 2308
Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #3 on: July 28, 2015, 08:50:01 PM »
Magic happens when you press the button on a K-bike.  To understand all the things that happen when you turn the key and press the button, read Bert's troubleshooting page.

Wives like ours are hard to find.  Mine convinced me to buy my second bike, the M-G, when I was sitting on the fence.  She said "Sure, get it.  It's cheap.".  She refuses to ride any of them though.
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  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline jakgieger

  • itinerant farmer
  • ^ SuperNatural Motobricker
  • Posts: 618
Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #4 on: July 28, 2015, 09:15:27 PM »
Thanks alot...this will be a big help! For the past three weeks, working on this bike with my kids, the anticipation has been really building.  It was a real let down to find the old gas, but we keep moving on.
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline billday

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Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #5 on: July 28, 2015, 09:30:09 PM »
Welcome!

I assume you've been here: http://www.motobrick.com/index.php/topic,666.0.html
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  • New York State, USA 10977
  • 1985 K100

Offline rbm

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Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #6 on: July 28, 2015, 09:41:57 PM »
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  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline jakgieger

  • itinerant farmer
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Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #7 on: July 28, 2015, 10:27:56 PM »
NO...usual farmer style I'm a little backwards :hehehe.  I am waiting on the injectors (just plugs sitting there now).  I am COMPLETELY renewing the fuel system...pump, filter, hoses, sending unit, injectors, rail.  While waiting on the injectors, I put the tank on anticipating that the pump would run with the key on.  Well, the pump runs, but only when I arc to the battery, so I started investigating the relay and fuse.  I have power to the relay (red wire), but no power out.  The relay tests good.  Hopefully the problem is as simple as the "computer ECU" is sensing there are no injectors present :nono and not powering the pump relay.  The injectors will be here by Saturday, so we can spend the weekend working on it with the technical info you guys have provided.  Thanks
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline jakgieger

  • itinerant farmer
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  • Posts: 618
Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #8 on: July 31, 2015, 08:54:33 PM »
OK...way overthinking it!!! The osidetiger injectors came today...and...another K bike is resurrected!!!  Very slow to start initially :riding:, but when she did she ran nice.  Took her to 110 and all the gauges, etc. seem to be working (even the ABS).  You've gotta love German engineering.  Thanks guys for the other threads on LED lights.  I have installed them and modified the flasher control.  Next, the 100w headlight, and then we are ready for the road.  I took my daughter for a ride after the bike checked out and scared the hell out of her (a little insurance for later dating :hehehe).  The boys were afraid to ride after they tried to follow me on the 4 wheeler :mbird.  I really appreciate this forum and all the technical assistance.
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline rbm

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Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #9 on: July 31, 2015, 08:59:54 PM »
Don't even think about replacing the 55/60 halogen with a 90/100 unless you first install a headlight relay kit and beef up the wiring to 12GA or better, with direct runs to the battery.  Also consider replacing the OEM plastic headlight socket with a ceramic one, unless you really like melted plastic, dead handlebar controls  and no light.  Seriously!!
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  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline jakgieger

  • itinerant farmer
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  • Posts: 618
Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #10 on: July 31, 2015, 11:53:33 PM »
Yes, I ordered the relay kit from easternbeaver.  On the farm I have learned a few things about wiring, and I will cut/solder and fit the relays appropriately.  What about the ceramic housing?
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline rbm

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Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #11 on: August 01, 2015, 12:50:13 AM »
lookup this Ebay ID and you'll see what I'm talking about.  ==> 351381505569  <==  These should also be available from aftermarket auto supply houses and possibly car wreckers.
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  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline jakgieger

  • itinerant farmer
  • ^ SuperNatural Motobricker
  • Posts: 618
Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #12 on: August 01, 2015, 08:52:07 AM »
OK, can do.  Most appreciated as I like to run at night (fewer idiots on the road).  I may run to Canada (Alberta) later this month.  This whole summer has been a washout on the farm (too much rain/lost the 1/2 the wheat), and the bike has given me something to do to keep my sanity.  I have a good friend and shirt-tail cousin by marriage whose daughter is getting married...
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline ts888

  • ^ Motobrick Curious
  • Posts: 50
Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #13 on: August 04, 2015, 09:45:06 PM »
Congrats on resurrection!  I am riding a resurrection special m'self, and I love it.

For an answer to your original question -- Kbricks use Bosch L-jetronic. This particular flavor of injection uses a wiper-contact (rheostat) air flow meter.  The fuel pump will only operate when the starter is cranking or the AFM flap is open -- i.e. not sitting on the stop, i.e. the engine is running and sucking in air.  The common test for an L-Jet fuel pump is to turn the vehicle on, and poke a finger in the AFM to open the flap and active the fuel pump relay.  if the pump runs, it's not the problem!
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Offline jakgieger

  • itinerant farmer
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Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #14 on: August 04, 2015, 11:42:03 PM »
Thank you ts888 for the technical answer...Thankfully, I did not have to get in that deep, although I was seriously having my doubts as we cranked it the first time.  We did hear the pump running intermittently when we started cranking, finally fire and a big cloud of smoke :clap:.  The stability, through time and neglect, of this design is rather amazing...
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline jakgieger

  • itinerant farmer
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  • Posts: 618
Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #15 on: August 09, 2015, 08:23:00 PM »
So, here is a picture of the bike and the pit crew.  We have been taking the "flying circus" for rides in the evening.  Kind of a dream come true working with the boys on something they are excited about...that isn't TV or a computer game :clap:  The reynolds rack is installed...and being put to use!  Thank you guys for all the help.
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline TrueAce

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Re: When does the fuel pump actually run, and what triggers the relay?
« Reply #16 on: August 28, 2015, 09:24:45 PM »
ZOOOOOOOOOM........beautiful, start them young!!
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  • Florida
  • '85 K100GS, '85 K100RSSC,', '94 K1100RS,'10 S1000rr,'14 Ural Sidecar, '15 R Nine T
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