Fuel Gauge acting strange

[chocker]

Hi,
I have a little problem with my fuel gauge. It was working great since I have had it, very smooth and reading well. I hadn't used the bike for a couple of weeks and I tried to start it and the cranking was going a little slower. I put it on the trickle charger for about 15 minutes as it was right next to the bike. The bike started up great. I now see the fuel gauge going really slowly then stopping at about a quarter tank. I know there is about half or more of a tank left and even if it were at that level, the needle wouldn't usually go that slow. I looked in the tank and saw the the rod on the right and it didn't seem to be stuck. I will try to fill the tank and see what happens. If anyone has any other ideas as well, that would be great.

Thanks,
Mark

[aviationfred]

I haven't had the same issue that you have.

I did have an issue that my fuel gauge started reading max full all the time. The fix was to replace the fuel sending unit/float switch.


Fred

[red]

Chocker,

One common problem with the fuel gauge is a bad (corroded) ground.  Connect a jumper wire (using small alligator clips or similar) from the sender unit ground to the fuel gauge ground at the instrument cluster.  If that perks things up, clean up the bike's ground connections at each end, and you should be good.  Aside from that, you may have to replace the sender unit, but most of the time when somebody does that, what they really did to fix the problem was just cleaning up the ground and electrical connections.

Keep in touch,
Red

[fjaap]

I replaced both the sender and the gauge last year, but to no avail.
Still the needle bounces like crazy, but somehow as soon as the tank is only about 1/8 full, it calms down until Empty.
I already suspected grounding issues, as soon as I am able (had surgery on my knee in May and need to wear a brace for 6 weeks) I will get onto it.

[chocker]

Hi,
thanks for the information. I will try the ground test. The gauge was always smooth, never any jumping. Is it hard to get to the ground wire from the gauge? I have dealt with doing the LED replacement with the relay so I have gone up there.

Mark

[red]

Hi,
thanks for the information. I will try the ground test. The gauge was always smooth, never any jumping. Is it hard to get to the ground wire from the gauge? I have dealt with doing the LED replacement with the relay so I have gone up there.
Mark

Mark,

On my 1985, just unscrew four bolts (Index #8 & #14) in this drawing
http://www.2wheelpros.com/oem-parts/1985-yamaha-fj1100n-fairing-1-assembly.html
from the cowling, disconnect the speedometer cable, and flip the entire cowling forward and upside down in front of the bike.  The headlight adjuster is a one-bolt affair.  If you can find the same "cowling" drawing for your year of FJ on that web site, you should be able to work out how to get into the instruments.

I do not have all the wiring diagrams, but ground will probably be a black wire.  You may be able to download an Owner's Manual for your bike from Yamaha in Oz:
http://www.yamahaownershandbook.com.au/?r=0
The Owner's Manual will have the wiring diagrams in the back.  Your bike may not be exactly the same as what shows in the Owner's Manuals, but close enough to be useful.  A copy shop should be able to print and three-ring punch your manual, for a reasonable fee.

Cheers,
Red

[chocker]

Thanks for all the information. I have a manual. I have removed the gauges in the past to replace the plastic gauge cover and put LEDs in as well.. Would I be able to get to the fuel gauge from underneath without all that meaning just removing the horn and try from there.

Mark

[chocker]

Hi,
after all that it turns out that it was working fine I thought it wasn't because I only had about 155 km on the odometer and that sounded weird because I usually get around 300 km per tank. I realized that it hadn't been filled since being in the garage since the winter and I went through a lot of traffic. I refilled it and the needle went nice and smoothly to the full tank line. Thanks for all the help.

Mark

[fj1289]

Thanks for the follow up - and glad you solved the "issue"!