Fuel Sensor Orientation

[kz6fittycent]

I recently replaced my fuel pump with a kit from Rev-Mo: https://www.rev-mo.com/fuel

That sucked - the process. It was no fun and I don't want to do it again until I have to replace the fuel filter.

Things are going well though. The bike runs REALLY well and the pump is very quiet. I like it.

That said, I was putting some miles on the bike to continue with my shakedown and test the "new" distance for the fuel light, but it never came on. I replaced the sensor with a new one from the kit I mentioned above.

I tested all the connections before putting the pump in, and once more afterward, everything is good.

But, no light at the normal 120 miles I was seeing before.

So, I started thinking back and realized that I'd installed the dang sensor upside-down from the way I took the old one out. :upset:

I looked up later model pumps and noticed that the sensor is on it's side, instead of vertical (like my early-2005 XB). So, now I'm wondering if it matters, and I just didn't put that last couple of miles on the bike to get the light to come on. Since mine is installed upside down, it would make the sensor "lower" than stock.

It's not a big deal, really. It's more irritating than anything else and I can just make sure I refill at 120 like normal, but dang it Bobby...I gotta know.

TIA.

After pump rebuild:


As you can see, the sensor is orientated with the wire on top. Don't know what I was thinking, but it's done now...

 

[mike lowary]

Has your low level fuel light come on yet?

 

[kz6fittycent]

No I filled it up at 120 miles yesterday so I'll just have to ride it some more (bummer ) to see if it comes on at 130 or something.

 

[mike lowary]

That’s what I’m wondering. Maybe you’re getting better fuel mileage now?

 

[kz6fittycent]

Good point. That new FPR...

 

[mike lowary]

I would try to get the low level light to come on. The fastest way to check the light is to drain the fuel. I would get to the 120 mile mark again then pull the drain plug on the pump. That will at least tell you if the light is working.

 

[mike lowary]

You have 2 things we need to figure out. 1-is the light working. 2-is the light coming on at the correct time.

 

[mike lowary]

Does your frame have the hole in it for the intake?

 

[kz6fittycent]

Does your frame have the hole in it for the intake?

Yeah it does.

 

[kz6fittycent]

You have 2 things we need to figure out. 1-is the light working. 2-is the light coming on at the correct time.

Well, the light DID work, that much I know. So #2 would be my focus here.

 

[mike lowary]

Ok John you’re up. At what point does the low fuel level light supposed to come on.

 

[mike lowary]

Once we find out at what point it’s supposed to come on I would drain the tank completely. Then add gas a few oz at a time until the light goes off. Add up how much gas you put in and compare that to what John says.

 

[mike lowary]

It’s a little bit of work, but it’s still easier than pulling the pump again.

 

[kz6fittycent]

It’s a little bit of work, but it’s still easier than pulling the pump again.

Yeah very true. If it never activates, lazy me is just gonna wait til it needs a new fuel filter.

 

[Barrett]

i don't know where that outfit sources their fuel level sensors nor can i vouch for the quality of same...BUT the factory sensors that i still keep in stock are thermistors. yours would be as well. it is supplied 12V thru the main pump feed and the housing is grounded. it doesn't know its orientation, nor does it care. the 12V supply adds a bit of warmth to the "innards" and the resistance is read via the ECM. the fuel acts as a heat-sink and keeps the sensor at a constant temperature. as the fuel level decreases, the sensor warms up changing the ohms value that the ECM is seeing...and when a pre-determined ohms value is seen by the ECM....your low fuel level light activates and trip-1 commences its mileage count. i'd leave it be.

 

[kz6fittycent]

i don't know where that outfit sources their fuel level sensors nor can i vouch for the quality of same...BUT the factory sensors that i still keep in stock are thermistors. yours would be as well. it is supplied 12V thru the main pump feed and the housing is grounded. it doesn't know its orientation, nor does it care. the 12V supply adds a bit of warmth to the "innards" and the resistance is read via the ECM. the fuel acts as a heat-sink and keeps the sensor at a constant temperature. as the fuel level decreases, the sensor warms up changing the ohms value that the ECM is seeing...and when a pre-determined ohms value is seen by the ECM....your low fuel level light activates and trip-1 commences its mileage count. i'd leave it be.

WORD! Thanks man! I'll keep an eye on it and circle back like Psaki.

 

[Barrett]

Ok John you’re up. At what point does the low fuel level light supposed to come on.

Hey there Mike: a fuel level sensor in good condition activates with about 3 US quarts of fuel left in the frame/tank.

 

[mike lowary]

Hey there Mike: a fuel level sensor in good condition activates with about 3 US quarts of fuel left in the frame/tank.

Thanks John.

 

[BuellyBagger]

i don't know where that outfit sources their fuel level sensors nor can i vouch for the quality of same...BUT the factory sensors that i still keep in stock are thermistors. yours would be as well. it is supplied 12V thru the main pump feed and the housing is grounded. it doesn't know its orientation, nor does it care. the 12V supply adds a bit of warmth to the "innards" and the resistance is read via the ECM. the fuel acts as a heat-sink and keeps the sensor at a constant temperature. as the fuel level decreases, the sensor warms up changing the ohms value that the ECM is seeing...and when a pre-determined ohms value is seen by the ECM....your low fuel level light activates and trip-1 commences its mileage count. i'd leave it be.

Wow, that is brilliantly simple!

John can u fix my faulty fuel gauge on my Harley?(site unseen over the interweb of course)

 

[Barrett]

Wow, that is brilliantly simple!

John can u fix my faulty fuel gauge on my Harley?(site unseen over the interweb of course)

Cody: Isn't yours a big-twin, as i recall? It would have been built at the York Production plant across the river from me. See if you can make arrangements to have it returned to York....tape a note to the tank telling my niece to notify me once it arrives...and i'll run over and take a look/see and get you fixed up. On-the-house, of course. Need her name?