ST1300: Fuel Indicator Problem

Well, I swapped my T-Stat, again, last night. Now, I've gone from 22mpg to 59mpg. I think.

Now, a new problem has developed:
The fuel gauge will operate normally until it gets down to 2 bars indicated. It hangs there until the fuel runs out completely, which is not nice since I tend to get stuck on the side of the road since I'm used to getting a blinky warning dash first.

The last two bars on the fuel indicator will not drop off as fuel depletes.

Any ideas?

Did you do anything with the fuel system like a fuel filter change?

I think I read that it is easy to disturb the floats and that my explain the issue.

Check the thermistor in the lower tank. Perhaps you did something that disturbed the wiring.

--Mark

I did a quick search and came up with this post but I don't know that it is the problem that you are having for sure. Too bad there is no resolution that I saw.

Link

From what I have been seeing, once you hit 2 bars your upper tank is empty. So if it doesn't drop below that, whatever measures fuel in the lower tank must be having an issue. Check connections like Blrfl mentioned.

Page 24-7 in the service manual goes over operation of the fuel gauge. That may help some.

Did you disconnect the battery when doing the t-stat? It may have thrown things off on this tank.

Pg 22-18 covers trouble shooting the fuel gauge.

Just how much fuel will we need for the ERC course? The 1300 has about a 300 mile range right? Oh that's right it is in Oklahoma City

Easty..
SAME Here but its intermittent...
Currently I have changed the fuel filter (it needed to be done)..now have some rough idle issues when cold (probably not related but who knows)...

Fuel float seems to be working fine as well..(had it out and it was clean and moving freely)

Will be doing a compression test in the next couple of days..

AS to the fuel, could be a venting issue as well..Brian and I checked most of the vent lines (including Ts connections) last night..More to come...Let me know what you find out as well...

I'm pouring over the manual right now. I'll check those pages, Senn.

Kempo - it's good to know that the problem, at least, has been seen before by someone else. Looks like you've eliminated some of the things I was wondering about. Have you tried something simple like Sea Foam, or some additive to clear a potential obstruction?

sennister said:

From what I have been seeing, once you hit 2 bars your upper tank is empty. So if it doesn't drop below that, whatever measures fuel in the lower tank must be having an issue. Check connections like Blrfl mentioned.

Click to expand...

According to the diagram on 24-7, two bars would still have fuel in the upper tank. The single blinking bar initiates when the upper tank is empty, meaning you have 5Liters (1.32 gallons) left in the lower tank. So, in my case, when the upper fuel tank drains completely, the reserve sensor is not activating. This would support both Mark and Dave's initial ideas. The first step appears to be pulling the fuel pump assembly from the lower tank and seeing if all the wires are proper.

May as well replace the fuel filter since I'm in there...

BUT... if the fuel level indicator is "hanging" with an indication that the upper tank still has fuel, and is not dropping when the upper is empty... I'm wondering if the fuel level sensor in the UPPER tank is at fault? Is it indicating fuel when there is none there?

+1 on checking the lower tank sending unit...( if it goes from 2 to empty)


The 3 bars to 1 is the upper tank unit that many have have problems with. ( BTW, mine did this now and then till this winter when I let it sit for the 2 months with Seafoam in the tank... haven't seen the problems since )
Due to this I always reset the trip odo ... at 250-275 I look for gas.

EASt said:

I'm pouring over the manual right now. I'll check those pages, Senn.

Kempo - it's good to know that the problem, at least, has been seen before by someone else. Looks like you've eliminated some of the things I was wondering about. Have you tried something simple like Sea Foam, or some additive to clear a potential obstruction?

Click to expand...

No but I should...All the injectors are out of the bike...I may soak them for a couple of days just for ha ha's..lets stay in touch on this one..

Kempo-STer said:

No but I should...All the injectors are out of the bike...I may soak them for a couple of days just for ha ha's..lets stay in touch on this one..

Click to expand...

It's a plan. I'm gonna put some additive in just for skittles 'n' beer, but I'm probably going to start pursuing this as an electrical issue in the lower tank.

EASt said:

It's a plan. I'm gonna put some additive in just for skittles 'n' beer, but I'm probably going to start pursuing this as an electrical issue in the lower tank.

Click to expand...

while down there...check the flow of your fuel filter...mine was pretty clogged..easy swap if you are going to be into the lower tank..

EASt said:

According to the diagram on 24-7, two bars would still have fuel in the upper tank. The single blinking bar initiates when the upper tank is empty, meaning you have 5Liters (1.32 gallons) left in the lower tank. So, in my case, when the upper fuel tank drains completely, the reserve sensor is not activating. This would support both Mark and Dave's initial ideas. The first step appears to be pulling the fuel pump assembly from the lower tank and seeing if all the wires are proper.

May as well replace the fuel filter since I'm in there...

BUT... if the fuel level indicator is "hanging" with an indication that the upper tank still has fuel, and is not dropping when the upper is empty... I'm wondering if the fuel level sensor in the UPPER tank is at fault? Is it indicating fuel when there is none there?

Click to expand...

The initial comments about the upper tank being empty when at 2 bars was based on what I was reading in a couple searches I did here stated. I tend to believe the book more and that there is still a little gas in there.

I haven't done a T-stat replacement because I don't own a 1300, or do I, either way I haven't done one so does that require you to prop up the tank like when changing an air filter? Maybe some electrical bits became disturbed on the upper sending unit?

sennister said:

I haven't done a T-stat replacement because I don't own a 1300, or do I, either way I haven't done one so does that require you to prop up the tank like when changing an air filter? Maybe some electrical bits became disturbed on the upper sending unit?

Click to expand...

The fact that you're quoting from an ST1300 shop manual tells me you just bought a 1300. The jig is up. Do I get a prize?

This winter, I pulled the tank off completely, removed the air cleaners, pulled the throttle bodies below that, cleaned all the lines therein, and then replaced all my water hoses.

SO, the odds that I mis-connected a fuel line or wire are good, as is the likelihood that I may have shorted or nudged something. Clearly, the electrical bits could have been disturbed.

EASt said:

The fact that you're quoting from an ST1300 shop manual tells me you just bought a 1300. The jig is up. Do I get a prize?

This winter, I pulled the tank off completely, removed the air cleaners, pulled the throttle bodies below that, cleaned all the lines therein, and then replaced all my water hoses.

SO, the odds that I mis-connected a fuel line or wire are good, as is the likelihood that I may have shorted or nudged something. Clearly, the electrical bits could have been disturbed.

Click to expand...

No, I actually have had the shop manual for a couple years now on the 1300. Since I am at work and I typically don't travel with my library of manuals means I am using a PDF version of the manual that I am viewing through a remote desktop session to one of my computers at home. I actually am typing this on the same remote session. Actually there are 3 members of this board that have seen me on my new ride and we have chatted about it. In all I think there are 10 people that know what I got. They have all been sworn to secrecy though. :

You are just going to have to show up for the ERC in Decatur Il, if you want to find out what I got for sure. You know I will be there. I am about 95% sure I will make it to Betty's.

Good luck with the diagnostics.

I had to drop out of the ERC. I never thought I'd say this but... "I just don't trust my ST".

My problems with the motorcycle have come on fast and furious. 55k without a single glitch and then, wham, everything starts breaking.

Oh, well, at least my final drive isn't aflame. ;-)
Posted via Mobile Device

EASt said:

I had to drop out of the ERC. I never thought I'd say this but... "I just don't trust my ST".

My problems with the motorcycle have come on fast and furious. 55k without a single glitch and then, wham, everything starts breaking.

Oh, well, at least my final drive isn't aflame. ;-)
Posted via Mobile Device

Click to expand...

Yeah, I saw your post. Looks like Kevin jumped on the opening. He just mentioned yesterday that he wanted to go.

Well Betty's it is I guess.

I've had this same problem for about one year now. The first time I discovered it, I was in BFE on the way to an RTE when the engine sputtered and then stopped. When I looked at the fuel gauge it had gone from two bars to flashing bars. Fortunately, I was only about a block away from a farmhouse and was able to get a gallon of gas from them.

I haven't figured out the problem yet although there are a few things I'm going to look into a little bit closer. The biggest PITA about this is if it is truly a bad thermocouple in the fuel pump assembly you're screwed. You have to buy the whole damn pump assembly $$$$$.

Open up the three terminal fuel pump connector and see if you have any corrosion in the terminals. Another possibility, I had removed the whole front plastic and dash off of my bike early last year and I'm wondering if I didn't get that 20 pin connector plugged in properly?

The manual on page 22-19 step 5 has you measure the Fuel Reserve Voltage between the Brown/black wire and ground. On my bike with a full tank I measure 9.91V (I used one of the bolts of the seat adjuster for ground). What does yours measure? The manual states that the sensor is bad if the voltage reading is near the battery voltage. ***** does near mean in this case?!? 0.1V?, 0.5V?, 1.0V?

In the meantime I have simply done what I always have done in the past and that is reset my A odometer and average MPG calculator every time I get gas. I then have a rough idea on how far I can go before I run out. Stay tuned...