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General Category => Yamaha FJ1100 / FJ1200 Running Problems => Topic started by: Deano on May 18, 2012, 07:26:24 PM

Title: fuel starvation problem
Post by: Deano on May 18, 2012, 07:26:24 PM
hi  guys  need  your  wisdom 

i  have  a 1988 fj1200  it  starts  great  can ride  it  for  about 10 mins  then  it starves  itself  of  fuel i shut  it  off and  restart  runs  fine  for  about  the  same  amout  of  time  then  have  to  restart  it  again  ive  switched  pumps  and  pump relays   and  have  tried  rideing  with  cap  open  .  it  has  to  be  something  simple  i  hope!!!!!  please  help!! 


thanks  Dean Ritchie  in  victoria  bc
Title: Re: fuel starvation problem
Post by: Dan Filetti on May 18, 2012, 08:44:28 PM
Dean-

See if the problem goes away riding with the gas cap open.  If so, then you need the gas cap flapectomy.

Dan
Title: Re: fuel starvation problem
Post by: Dads_FJ on May 18, 2012, 11:14:37 PM
kinked gas line?  have you had the tank off Dean?
Title: Re: fuel starvation problem
Post by: flips on May 19, 2012, 02:05:04 AM
Hi there  :hi:

+1 to what Dan & Dads_FJ

This happened on my 86.The fuel lines kinked.I followed Mr blackstock's lead to fix it.

http://www.fjowners.com/index.php?topic=4411.msg38941#msg38941 (http://www.fjowners.com/index.php?topic=4411.msg38941#msg38941)

Might even be a fuel cap venting issue....might need a "flapectomy"

http://www.fjowners.com/index.php?topic=2024.0 (http://www.fjowners.com/index.php?topic=2024.0)

Cheers  :drinks:

Jeff P
Title: Re: fuel starvation problem
Post by: Deano on May 19, 2012, 01:53:21 PM
Quote from: Dads_FJ on May 18, 2012, 11:14:37 PM
kinked gas line?  have you had the tank off Dean?



yes  ive  had  the  tank  off  didnt  see any  kinks  and  ive  tried  the  open  cap    still  same  .  i  just  dont  get  how  it   runs  great  for  a few miles  then  dies  and  after  restarting  it  runs  great  again  for  same  amount  of  time 

ty for  your  reply Dean
Title: Re: fuel starvation problem
Post by: Pat Conlon on May 19, 2012, 01:56:42 PM
Quote from: Pat Conlon on May 19, 2012, 11:01:04 AM
You can pull your tank off, look at the lines and everything looks fine.
Only to put your tank back on, and have the kink reappear when things get warm.

My advice is to....Follow exactly, the factory oem fuel line routing
The single hose from the petcock to the Y splitter should be run *under* the 2 branch lines.
If you run the petcock line on top of, or over, the branch lines, you will get a kink.
Title: Re: fuel starvation problem
Post by: FJmonkey on May 19, 2012, 02:11:29 PM
Quote from: Deano on May 19, 2012, 01:53:21 PM
yes  ive  had  the  tank  off  didnt  see any  kinks  and  ive  tried  the  open  cap    still  same  .  i  just  dont  get  how  it   runs  great  for  a few miles  then  dies  and  after  restarting  it  runs  great  again  for  same  amount  of  time 
ty for  your  reply Dean
With a kinked line the fuel flows slower or not at all. Imagine that the kink is slowing the flow down, like the hose got smaller. With the engine at idle the fuel demand is minimal.  The reduced fuel flow has no problem keeping bowls full. Once you start riding the fuel demand increases. The demand will eventually be greater than the kinked hose can provide and the bowls go empty. Now that you are stopped at the side of road wondering what hell is going on, the fuel has a chance to catch up and fill the bowls again. Same thing happens if the fuel tank goes into a vacuum lock. The air pressure in the tank is reduced when fuel drains into the carbs and the filler cap does not allow air in. Crack open the cap and air pressure equalizes and fuel flows freely again till a vacuum is formed again. The "Flapectomy" insures that the now missing flap cannot seal the air out while riding. A clogged fuel filter will also restrict flow. Some owners have discovered that the PO put one on, not knowing it was there they never changed it. Not sure but I am guessing that your 88' is a gravity feed like the 84 to 87 years. Hope this helps.
Title: Re: fuel starvation problem
Post by: Travis398 on May 19, 2012, 03:09:14 PM
Quote from: FJmonkey on May 19, 2012, 02:11:29 PM
Not sure but I am guessing that your 88' is a gravity feed like the 84 to 87 years.

88 was the first year for the fuel pump

Hope that helps

and it sounds like he already checked that.................

Quote from: Deano on May 18, 2012, 07:26:24 PM
hi  guys  need  your  wisdom 

i  have  a 1988 fj1200.....................................  ive  switched  pumps  and  pump relays   and  have  tried  rideing  with  cap  open  .  it  has  to  be  something  simple  i  hope!!!!!  please  help!! 


thanks  Dean Ritchie  in  victoria  bc
Title: Re: fuel starvation problem
Post by: FJmonkey on May 19, 2012, 03:15:17 PM
Quote from: Travis398 on May 19, 2012, 03:09:14 PM
88 was the first year for the fuel pump

Hope that helps

and it sounds like he already checked that.................

Quote from: Deano on May 18, 2012, 07:26:24 PM
hi  guys  need  your  wisdom 

i  have  a 1988 fj1200.....................................  ive  switched  pumps  and  pump relays   and  have  tried  rideing  with  cap  open  .  it  has  to  be  something  simple  i  hope!!!!!  please  help!! 

thanks  Dean Ritchie  in  victoria  bc
This why I don't hunt for crocodiles or poisonous snakes. I'd be standing right on top them wondering where the hell they went...  :dash2:
Title: Re: fuel starvation problem
Post by: Pat Conlon on May 19, 2012, 04:36:47 PM
....and I'm standing right beside Mark wondering WTF just bit me..... :dash2:
Title: Re: fuel starvation problem
Post by: RichBaker on May 19, 2012, 10:08:17 PM
Have you checked that the pump has 12V when the engine stops running?  Tried switching the reserve switch?  Check the ground (earth, return) wire for continuity, maybe you have an intermittent wire....
Title: Re: fuel starvation problem
Post by: fj1289 on May 21, 2012, 11:40:07 AM
Along the line Rich is going down - also check the points on the pump.  They could be worn and sticking when they get hot, then work again for a while after cooling down.

Chris W. 
Title: Re: fuel starvation problem
Post by: Travis398 on May 21, 2012, 05:39:08 PM
Quote from: Deano on May 18, 2012, 07:26:24 PM

it  starts  great  can ride  it  for  about 10 mins  then  it starves  itself  of  fuel i shut  it  off and  restart  runs  fine

Are you sure it's out of fuel?
You can hear the pump run to fill the carbs, So I am guessing if they are drained (or dry) it would take a minute or so to fill them back up.

Which means the bike might not start right up like you are saying.

To add more confusion............The 88 model not only got the new fuel pump but also got the new (at the time) digital control ignition which provides the control circuit for the fuel pump.
Title: Re: fuel starvation problem
Post by: Deano on June 13, 2012, 06:19:16 PM
is  it  better  to  run  @low gear  hi  rpm  or  hi  gear  low  rpm  i meam  what  does  this  bike  like  better  1988  fj1200? 
just  wonderin  lol
Title: Re: fuel starvation problem
Post by: FJmonkey on June 13, 2012, 08:41:11 PM
Quote from: Deano on June 13, 2012, 06:19:16 PM
is  it  better  to  run  @low gear  hi  rpm  or  hi  gear  low  rpm  i meam  what  does  this  bike  like  better  1988  fj1200? 
just  wonderin  lol
Depends if you are racing or cruising, you have gobbs of grunt and only 5 gears. You be the judge.... The FJ power plant will give way more than most riders need or want. Pick your gear to suit your needs/wants.....
Title: Re: fuel starvation problem
Post by: psyhotron on July 21, 2012, 08:52:37 AM
Quote from: Deano on May 18, 2012, 07:26:24 PM
hi  guys  need  your  wisdom 

i  have  a 1988 fj1200  it  starts  great  can ride  it  for  about 10 mins  then  it starves  itself  of  fuel i shut  it  off and  restart  runs  fine  for  about  the  same  amout  of  time  then  have  to  restart  it  again  ive  switched  pumps  and  pump relays   and  have  tried  rideing  with  cap  open  .  it  has  to  be  something  simple  i  hope!!!!!  please  help!! 


thanks  Dean Ritchie  in  victoria  bc

Hi Deano, Hello Guys,

I've got a FJ 1200 ABS '93 and it seams that I have the same problem like Deano here. So when I turn the ignition key the fuel pump primes for ~10 sec. Then I start the engine and it goes like a thing from Mad Max until when I am passing by the 2nd roundabout then it is slowly dying to stop. Turn the key off and on again the pump primes again for 10 sec and it goes again ... This way I can only ride it at night when nobody can see :crazy: ... I did the 'flaponotomy' to remove flaps from the Filler Cap this didn't change nothing. The the tank breathing hose is free of blockages, Fuel lines tidy and have no bends. The other thing to mention is when I have removed fuel filter from underneath the tank and connected fuel hose from the tap directly into the pump this improved the way it goes but it hasn't fix the problem with fuel starvation. Can the ignition unit be at fault and not send signal to the fuel pump after the initial 10 sec priming session ?
I have replaced the fuel pump as well with brand new FJ type pump.




Title: Re: fuel starvation problem
Post by: andyb on July 21, 2012, 09:24:07 AM
Check the fuel filter? 
Title: Re: fuel starvation problem
Post by: SlowOldGuy on July 21, 2012, 09:32:16 AM
Could be the fuel pump relay going bad.  Try bypassing the pump completely by running a fuel line directly from the tank to the carbs and see it that makes it run longer.

DavidR.
Title: Re: fuel starvation problem
Post by: psyhotron on July 21, 2012, 09:37:08 AM
Can I try to connect 12V and GND directly to fuel pump?
Title: Re: fuel starvation problem
Post by: fj11.5 on July 21, 2012, 05:00:07 PM
yes, just dont run it too long if its not pumping anything  (popcorn)