Blinking Fuel Gauge-Troubleshooting

rayzorx

Joined
Apr 30, 2008
Messages
8
Location
So Cal
Hi all,
I've got the dreaded all blinking fuel bars with the _ _ _ under them.
I've gone through the TS steps in the manual and have gotten to the last step where is says the reserve fuel sensor is bad or the instrument display is bad.
That's it, nothing after it as to the next step.

So my question is how do I test the reserve fuel sensor? Or the display, to determine which it is? Anybody know?

thanks
Ray
 
rayzorx said:
Hi all,
I've got the dreaded all blinking fuel bars with the _ _ _ under them.
I've gone through the TS steps in the manual and have gotten to the last step where is says the reserve fuel sensor is bad or the instrument display is bad.
That's it, nothing after it as to the next step.

So my question is how do I test the reserve fuel sensor? Or the display, to determine which it is? Anybody know?

thanks
Ray
Click to expand...

Mine went out at 30k. Had same issue and they started with the float, then went to the gauge, and found the fuel sensor bad, which is part of the fuel pump unit in the reserve tank. :eek:4:

Good luck! :pray1:
 
Anyone-
Is there a way I can test the lower tank sensor before I pony up the $$?
Ray
 
Thanks,
I went through all the TS steps again last night just to be sure. On the one step where you check voltage between the black/brown wire and ground I got a reading of 10.48vDC. The manual says that if this reading is "close to your battery voltage, the reserve fuel sensor is bad" This seems a bit nebulous to me.

Anyway, my battery measures at 12.01vDC. So is 10.48vDC close enough to confirm it's the lower fuel sensor?

Ray



RadioFlyer said:
Hi Rayzorx, I had this same problem on my bike (https://www.st-owners.com/forums/showthread.php?t=89858). A new fuel pump was the solution. Don't forget that if you change out the gauge cluster, your mileage gets set back to zero so you'll need to include a trip to DMV as well. Good luck!
Click to expand...
 
rayzorx said:
Thanks,
I went through all the TS steps again last night just to be sure. On the one step where you check voltage between the black/brown wire and ground I got a reading of 10.48vDC. The manual says that if this reading is "close to your battery voltage, the reserve fuel sensor is bad" This seems a bit nebulous to me.

Anyway, my battery measures at 12.01vDC. So is 10.48vDC close enough to confirm it's the lower fuel sensor?

Ray
Click to expand...

I had issues where the fuel display would show two bars (for a looong time)and then suddenly fall all the way to a flashing dashing line as it was about to run out of fuel. It would never go into the blinking last segment mode. In my case the fix turned out to be to replace the lower tank themocouple (fuel reserve sensor).

Now how does this apply to your problem? In troubleshooting my problem I did perform that Fuel Reserve sensor voltage measurement and in my case I measured 9.91v the first time I measured it. I don't remember my battery voltage at the time but it was in the lower 12V range.

I fixed my problem by purchasing a used fuel pump assembly off of eBay and then swapping the thermocouple. I now have a spare fuel pump and filter in case I need them in the future.

If you want, I can send you my original lower tank thermocouple. You would at least be able to prove whether or not the thermocouple would solve your flashing display problem. You would need to have some rudimentary soldering skills in order to try this. The picture of the thermocouple is below.

Lower Tank fuel sensor.jpg
 
Well, I went through the trouble shooting and in step 5, measuring the voltage from the sensor, I get 0.02 volts, certainly no where near batt volt of 12.7.

The tank is close to empty ( can't tell cause the fuel gauge isn't working :) )

I do get ~ 3 ohms measuring from the sensor wire ( brown/black) to ground .

I guess I'll fuel up tomorrow and see if I get close to 9v .

Scooter, could you measure the resistance of the sensor out of the tank ?

Is there any way to obtain the sensor part without having to buy a $400 + fuel pump ?
 
v8-7 said:
Is there any way to obtain the sensor part without having to buy a $400 + fuel pump ?
Click to expand...

The sensor isn't available separately as a Honda part. Thermistors come in a pretty wide variety of configurations, so it's not like you can pick one off the shelf and expect it to work. Also, you'd have to do the replacement in such a way that the job will survive spending most of its life submerged in gasoline.

--Mark
 
v8-7 said:
Scooter, could you measure the resistance of the sensor out of the tank ?

Is there any way to obtain the sensor part without having to buy a $400 + fuel pump ?
Click to expand...


I measured 1785 ohms @ 64 deg F from the thermocouple that you see in the picture.

You can get complete fuel pump from eBay but it pays to lurk around for a deal. One very lucky individual got this one for $29.95! linky
 
Lucky , indeed !

I may throw a 1-2k resistor in line and see if the gauge gives me a reading .

At least that will confirm the thermocouple .

Thanks for checking
 
My bike is just screwing with me now....

I buttoned it up and took it for a ride after about 1 minute the fuel gauge started working
for about 2 minutes, then stopped again.

Filled up the tank and again, after about a minute, it started working , then again it stopped.

Put about 30 miles on it and once again it started working..
Worked for another 25 miles.

I got home and shut it off.

I found this info while googling around.
Although it is for a Gold Wing warning light, I bet it's the same thermistor .

If my gauge stops working again, I'll probably pull the pump unit out and try to replace the thermistor .

"With that said, and many thanks to the unknown author for the detail presented, here is the best documentation on replacing the Low Fuel Level sensor that I have seen.

GL-1500 Fuel Reserve Sensor Repair:

Many sensors just stop working, so there's NO low fuel light warning.

This is how I accomplished my repair in about 45 minutes, was very easy to do; costs almost nothing, compared to Honda's fix: Buying new fuel pump assembly, at cost of $300+.

This is written for that percentage of the population who might not be as mechanically proficient as you; please take no offense. You'll need to purchase a thermistor from a local electronic parts supply house, with the following specs: 1000 ohms @ 25 degrees C, NTC (Negative Temp. Co-efficient).

To begin with: you'll be working around an open fuel tank. If you don't understand spark, static electricity, volatile vapors, 3rd degree burns, death; your house, garage, Wing burning & any other potential risk of working around gasoline/ vapors, I strongly recommend you pay the price and have a Honda shop do the work. You must be willing to take full responsibility for whatever may happen. This is very dangerous; do it outside. Also, if you aren't proficient at soldering, find a friend who is.

With all that understood, remove the seat.

There are (six) 10mm nuts on the top of the fuel pump assembly, remove them after you disconnect the electrical leads. As you disconnect the fuel line, have a rag handy to catch fuel that will run out of the hose. Trust me; you'll need to do this. Get another rag handy for the following step.

With everything disconnected, slowly lift fuel pump assembly. You'll notice another fuel line connected INSIDE the tank. Slide it off and work fuel pump assembly out of opening. Wipe off excess gas, then put a rag over open hole to minimize/ contain vapors. Let unit dry in the sun a few minutes. The fuel reserve sensor is what's best described as a "can" halfway down mounting arm of the fuel pump. It has one lead soldered to it. Pry, wiggle, push or otherwise GENTLY work the can free of it's mount on arm.

Don't bother to unscrew mount from the arm; just get the can out without ruining it. You'll need to bend the tabs to get it free; that's OK. Unsolder the single lead on can. Don't cut it; unsolder it.

Now you're holding the can only, in your hand. There's a base lip on the can, at the lead end. Slice the can open all the way around that lip, I used a Dremel tool and it worked easily.

Looking at other end of the can, you'll see a solder blob. That's where the other lead is attached to the can. Unsolder that and remove the larger end of the can; set it aside.

Unsolder the other end of thermistor and remove it completely from the can unit. Take new thermistor, cut ONE LEAD to a length of about 1/2" max. Leave the other lead full length. Solder short lead to the base (disc) center conductor area, where you just removed faulty sensor; make a good connection.

When putting the can together, route the other lead out end of the can, through hole. Be very careful when bending leads. You should hold them with needle nose pliers as a strain relief. Push can together, solder lead in place. You may also solder can itself shut. Do this only for some rigidity; don't try to seal it all the way around with solder.

Solder the single wire back on to sensor and place can back in its’ mount on pump arm. You'll need to squeeze mount to pinch the can. I tack-soldered mine back in it's mount; it held nicely. Put it all back together; it'll work fine."


( part # 527-2004-1K. DIA .22 1k Ohm. Cost was $1.07 each. It was available from http://www.mouser.com )
 
Last edited:
Rode to San Diego today, stopped for breakfast and when I restarted the bike I got the flashing fuel bars, after about 30 secs. the fuel gauge read normal and never had a nother problem... I see I am in for some fun.. and I just bought a new fuel filter(not installed yet).
 
Just wanted to give everyone an update and say Thanks for all the good responses.
I replaced the lower tank fuel pump and it did fix the problem.
BTW, I have a brand new upper sensor that I can't return, so if anybody needs one, I'll sell it at a good price.

Ray
 
rayzorx said:
Just wanted to give everyone an update and say Thanks for all the good responses.
I replaced the lower tank fuel pump and it did fix the problem.
BTW, I have a brand new upper sensor that I can't return, so if anybody needs one, I'll sell it at a good price.

Ray
Click to expand...
Ray, did you replace it yourself or have a dealer do it? How much was the pump and/or total job?

Skip
 
rayzorx said:
Just wanted to give everyone an update and say Thanks for all the good responses.
I replaced the lower tank fuel pump and it did fix the problem.
BTW, I have a brand new upper sensor that I can't return, so if anybody needs one, I'll sell it at a good price.

Ray
Click to expand...

Yep, that solved my issue too, it only took the dealer two to three weeks to figure it out. Because they would order a part, didn't fix it, send the part back and order an another part, didn't fix it, so send it back and order another part...until they finally got it...I doubt if they ever read the manual to actually TEST things! :eek:4:

Mine was covered under the warranty.
 
v8-7 said:
My bike is just screwing with me now....

I buttoned it up and took it for a ride after about 1 minute the fuel gauge started working
for about 2 minutes, then stopped again.

Filled up the tank and again, after about a minute, it started working , then again it stopped.

Put about 30 miles on it and once again it started working..
Worked for another 25 miles.

I got home and shut it off.

I found this info while googling around.
Although it is for a Gold Wing warning light, I bet it's the same thermistor .

If my gauge stops working again, I'll probably pull the pump unit out and try to replace the thermistor .

"With that said, and many thanks to the unknown author for the detail presented, here is the best documentation on replacing the Low Fuel Level sensor that I have seen.

GL-1500 Fuel Reserve Sensor Repair:

Many sensors just stop working, so there's NO low fuel light warning.

This is how I accomplished my repair in about 45 minutes, was very easy to do; costs almost nothing, compared to Honda's fix: Buying new fuel pump assembly, at cost of $300+.

This is written for that percentage of the population who might not be as mechanically proficient as you; please take no offense. You'll need to purchase a thermistor from a local electronic parts supply house, with the following specs: 1000 ohms @ 25 degrees C, NTC (Negative Temp. Co-efficient).

To begin with: you'll be working around an open fuel tank. If you don't understand spark, static electricity, volatile vapors, 3rd degree burns, death; your house, garage, Wing burning & any other potential risk of working around gasoline/ vapors, I strongly recommend you pay the price and have a Honda shop do the work. You must be willing to take full responsibility for whatever may happen. This is very dangerous; do it outside. Also, if you aren't proficient at soldering, find a friend who is.

With all that understood, remove the seat.

There are (six) 10mm nuts on the top of the fuel pump assembly, remove them after you disconnect the electrical leads. As you disconnect the fuel line, have a rag handy to catch fuel that will run out of the hose. Trust me; you'll need to do this. Get another rag handy for the following step.

With everything disconnected, slowly lift fuel pump assembly. You'll notice another fuel line connected INSIDE the tank. Slide it off and work fuel pump assembly out of opening. Wipe off excess gas, then put a rag over open hole to minimize/ contain vapors. Let unit dry in the sun a few minutes. The fuel reserve sensor is what's best described as a "can" halfway down mounting arm of the fuel pump. It has one lead soldered to it. Pry, wiggle, push or otherwise GENTLY work the can free of it's mount on arm.

Don't bother to unscrew mount from the arm; just get the can out without ruining it. You'll need to bend the tabs to get it free; that's OK. Unsolder the single lead on can. Don't cut it; unsolder it.

Now you're holding the can only, in your hand. There's a base lip on the can, at the lead end. Slice the can open all the way around that lip, I used a Dremel tool and it worked easily.

Looking at other end of the can, you'll see a solder blob. That's where the other lead is attached to the can. Unsolder that and remove the larger end of the can; set it aside.

Unsolder the other end of thermistor and remove it completely from the can unit. Take new thermistor, cut ONE LEAD to a length of about 1/2" max. Leave the other lead full length. Solder short lead to the base (disc) center conductor area, where you just removed faulty sensor; make a good connection.

When putting the can together, route the other lead out end of the can, through hole. Be very careful when bending leads. You should hold them with needle nose pliers as a strain relief. Push can together, solder lead in place. You may also solder can itself shut. Do this only for some rigidity; don't try to seal it all the way around with solder.

Solder the single wire back on to sensor and place can back in its? mount on pump arm. You'll need to squeeze mount to pinch the can. I tack-soldered mine back in it's mount; it held nicely. Put it all back together; it'll work fine."


( part # 527-2004-1K. DIA .22 1k Ohm. Cost was $1.07 each. It was available from http://www.mouser.com )
Click to expand...

This looks like a great write up...any pics?
 
I haven't replaced the thermistor yet, as my gauge has worked fine for the last 250 miles .

If I do. I'll be sure to write it up with pictures.

Looking at some of the data we have collected,
1. mine was intermittent
2. Scoot replaced his fuel pump assy' but his thermistor is still working
3. usually the fix is a fuel pump assy'

On my intermittent problem, I ruled out a bad connector , because it still didn't work after putting it back together , but then magically started working later.

Thermistors are usually pretty dependable devices and the amount of failures here
as well as other Honda bikes ( this is definitely a widespread problem ), seem
statistically large .

Perhaps it is a bad solder joint at the FP connection or within the FP assy'.

If my gauge goes out again, I will pull the FP assy' out , measure the thermistor , inspect all wiring and re-solder all connections .

There is a covering over the FP connection solder joints that is probably for anti-corrosion .
Has anyone removed that ? How does it come off ?

I haven't seen many reports of fuel pump failure , so I suspect those solder joints are good though.

Sorry for the rambling, just thinking out loud.
 
v8-7 said:
Looking at some of the data we have collected,
1. mine was intermittent
2. Scoot replaced his fuel pump assy' but his thermistor is still working
3. usually the fix is a fuel pump assy'
Click to expand...


Just to clear things up in my case, the original thermistor was indeed bad. I ended up replacing just the thermistor instead of the whole fuel pump assembly that I bought off of eBay because of some corrosion located on some of the brackets of the eBay unit.

The resistance measurement that is shown from post 11 was from the bad thermocouple.
 
Thanks for clearing that up..

I'll order some thermistors to have on hand if the gauge stops again..

Filled up the tank today and did ~ 50 miles and everything is still working.
 
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