Fuel starvation mystery when tank low

[maxtog]

My normal safe total range is around 250mi from the usable part of the 6.1 gal tank.  What portion is usable is, of course, debatable.   Fuel mileage is around 42 to 48MPG, so about 45 on average.  On fill-up, I always zero the A trip meter, and on entering reserve, I always set the B trip meter to zero (as near as feasible to the alert).   And on reserve, I typically have a range of at least 45 miles.

But apparently not today.

I went on reserve at around 200 miles (I can't recall the exact number, but it was close, and that is typical).  At 18 or something miles into reserve, I turned onto a highway and opened up the throttle and it kicked several times.  Obviously I quickly let off the throttle.  I thought it was a fluke.  Nope.  I drove non-spiritedly for a while and tried to accelerate a little more assertively and same thing.  I was already into gas station seeking mode.  I barely got to closest gas station at 232 miles total, was sputtering on hills or with even light acceleration.  There, I added 5.3 gal.  Problem disappeared immediately, as expected.  No issue on the 15 spirited miles home.

This is a bit mysterious.  I normally can go at least 45 miles on reserve without even worrying.   Has never happened before.  Since I have no explanation, I am just going to call it a fluke.  I am glad I can still say "I have never run out of gas in my life", although this was about as close as it has come.

[Boomer]

If you have an inline fuel filter, this is a common symptom of it being partially blocked. As the head of gas decreases it struggles to push the gas through the filter fast enough. If you don't have an inline filter, may be worth removing the petcock and checking the strainer on that.

I have run out of gas and had to push the bike 2 miles before I could get it somewhere safe to park it, following which I walked a further mile uphill to a gas station. In my case it was my own fault as I had forgotten to switch back to "On" the last time I filled up. After that I changed my fill-up routine from every other day to every day since I commuted 120 miles per day, and I have not used reserve since that day. I used to hit Reserve between 220 and 230 miles every other day so I rarely got very deep into Reserve. These days I reset my only trip (it's an '89) and when that gets close to 200 miles I start looking for gas.

[tynesidebob]

The 1400 has a filter inside the fuel pump which needs occasional cleaning.

[maxtog]

The 1400 has a filter inside the fuel pump which needs occasional cleaning.

Yeah, I kinda haven't ever done that before.  2011, 64K miles.

Could that really be a thing?  That it will struggle and go sputtering only when the tank is low?  I would think the fuel pump would be way more powerful than the difference between a full and low tank weight.

[gPink]

Yeah, I kinda haven't ever done that before.  2011, 64K miles.

Could that really be a thing?  That it will struggle and go sputtering only when the tank is low?  I would think the fuel pump would be way more powerful than the difference between a full and low tank weight.

Max, what are you calling reserve?

[maxtog]

Max, what are you calling reserve?

The point at which the low-fuel alert is triggered.

[Boomer]

My bad, I thought you were talking about a C10 with all the talk of Reserve.
On the C14 it is definitely the fuel filter in the pump, or more likely the pump itself, but change the filter first.

I had to do the filter on my C14 at around 70k miles and the old filter was very clogged.
Just changing the filter transformed my bike, especially when running on a low tank.
Yes, the difference between a pump with a clogged fuel filter and a pump with a clogged fuel filter AND 12" of head of fuel is not going to be much (0.7psi), but it makes a difference especially if that takes the fuel rail pressure below the regulated pressure.

[maxtog]

Damn.  I guess I have to add that to my list of eventual "to-do's"

[VirginiaJim]

Do you fuel up at the same station?  I've seen differences between brands as to how far I can go.  I prefer Exxon, Shell, Citgo...I guess all the top shelf gasolines should be good but there is the occasional fill up where the bike doesn't act right on starting or the tank mileage decreases.

[maxtog]

I almost always use Costco, and use the correct gas (high octane).

But, interestingly, that tank was one of the rare occasions where I went somewhere else because the lines at Costco were absolutely insane and I didn't have 20 minutes.  And I ended up paying $5 more due to that.

But the alert happened at about 200 miles, which is pretty typical, so I am not sure it is MPG.  Although I will admit I am not absolutely sure what the numbers were, because I didn't have any thought that something might have been different/wrong.

[VirginiaJim]

I wouldn't do anything to the bike until you've gone through a few tanks from another station..

[maxtog]

Good advice.  I will eventually update the thread with anything I learn.

[connie14boy]

Good advice.  I will eventually update the thread with anything I learn.

Run some Techron and/or Lucas injector cleaner thru it every 2,000 miles- I have 155k with no clogged fuel filters or stumbling, just sayin'.

[maxtog]

Run some Techron and/or Lucas injector cleaner thru it every 2,000 miles- I have 155k with no clogged fuel filters or stumbling, just sayin'.

I have used Techron on all my vehicles for decades.  Typically when the idle is rough or inconsistent.  Last use in the C14 was 05-25-2024  62,800mi, about 2,000 miles ago.  Before that was at 56,447, 51,663, 39,965, 38,225, 33,000, and 14,801.   Yep, I keep logs of everything

[VirginiaJim]

An old hippie walking through the neighborhood gave me some good advice years ago...  You may have some water in the tank as well so put in some of that stuff that will assist in getting the water out.  I think Techron might have something like that in it but it's been awhile and I don't have a bottle to look at.

[Pilgrim]

Why push it to that point?  Running low on fuel is not good for a few reasons.  Why not just start filling up when you get to 195/200 miles?

[zrx mitch]

An old hippie walking through the neighborhood gave me some good advice years ago...  You may have some water in the tank as well so put in some of that stuff that will assist in getting the water out.  I think Techron might have something like that in it but it's been awhile and I don't have a bottle to look at.

The most common one I see is HEET.

[tynesidebob]

In the UK it’s Wynn’s Dry Fuel. I use it every spring to get rid of the winter condensation.

[maxtog]

Still don't think by my symptoms it is water, since no problems starting and only an issue that one time when fuel was low and after fill-up, the problem went away immediately.  But it did jog my memory and I checked my log:

05-25-2024  62,800mi
Discovered the bike sat for two weeks with a full tank of gas that was not closed!  Some had evaporated.  At the station before going home, I pushed the cover down but got distracted and forgot to use the key and actually close it.  Drove home that way and didn't notice until next trip out.  I could smell the gas when I took the bike cover off.  Added ½ bottle of Techron.  Started and ran fine.

Didn't think anything of it after that.  I suppose it couldn't hurt to use half a bottle () of ISO-HEET.  Seems it is probably just pure Isopropyl alcohol.

[turbojoe78]

Max,
I believe somewhere on the forums, or in the Cog tech pages is a mod you can do to your gas cap so you don't need to use the key to close it.

You have to take it apart and remove some material from one of the pieces.

It's nice to be able to just open it with the key and then put the key right back and snap it closed when done filling.