LML fuel sender

[hully1]

Hi Gang,

I have purchased a new fuel tank without the autolube bottle as I have done away with mine. the question is will the LML sender unit work on my EFL loom/speedo? noticed it is different on the new sender to the old plastic one. any ideas?

[sime66]

I think LML fuel sender is two-wire (ground and fuel gauge), but EFL senders are three-wire (ground, fuel gauge and fuel warning light – with multi-plug). The LML speedo doesn’t have a fuel warning light; it has two (left/right) indicator warning lights instead.
Maybe the LML sender would still work just for the gauge (green and white wire on my wiring), but if it did work you’d lose the warning light.

[hully1]

Cheers Sime

Will be fitting a sip electronic speedo over the winter so will need to check to see if that is ok with the LML sender.

[sime66]

That terminal I’ve ringed above is just a 12v a/c going through the fuel gauge to ground via the variable resistance slide in the sender (the resistance increases as the fuel drops). The actual resistance might be slightly different, but the principal is the same for EFL and LML senders. On an EFL sender there is another connection that is made when the fuel is low, which completes the circuit (12v a/c to ground via the low fuel warning light and sender). If you still wanted the fuel warning light you could get a (BGM) fuel tap with the low-level warning wiring on it. I doubt whether SIP can say the working resistance range for their gauge, or LML can say the range for their sender, so it would probably be suck-it-and-see to see how accurate it was, but I don’t think there’s any other reason that an LML sender connection shouldn’t work if connected to an EFL or SIP fuel gauge.

[henri]

pretty much what i was thinking sime , seen guys asking for senders on facebooger an wanting piaggio or lml. so general consensus seems to be there interchangable .there might be a slight difference in resistances for full or empty so you'll have to keep a eye on fuel level til you suss the readings on gauge . but as originals can hardly be described as accurate something you'll be use too . H

[sime66]

I don’t think the LML sender cap would physically fit into an old tank as a replacement, though, H.
Hully has bought a new tank with the LML sender in it, if that works with an EFL speedo fuel gauge, which we agree it should - to a point and given they’re not that accurate anyway, I still don’t think you could fit that screw-down metal-capped LML sender in a PX/EFL tank, which has a plastic ¼-turn fixing, which gives rise to the question:
Will an EFL sender fit in Hully’s tank if the LML one doesn’t work with EFL/SIP speedo?
A few years back a chap I knew fitted a SIP speedo on an LML; with a bit of modding of the speedo multiplug it works. It must be OK because you can fit an LML speedo on a PX.
As long as sender and gauge are compatible it’s simpler for Hully though; an EFL has three wires to the sender:
· The gauge wire can still be used. (green/white on mine)
· The ground wire could still be used, although the LML one just grounds to the sender body, screwed into frame. (black)
· The warning light wire can be left disconnected, or connected to a wired fuel tap, like the BGM one. (white/black on mine)
With those small changes, I think the SIP speedo should then be the same at the multiplug.
But I suspect the fuel sender has to match the tank:

[hully1]

hi Guys,

yes Sime it is an LML tank which as you say has the 5 threaded holes for the metal sender surround. looking at it I don't think there is anyway the EFL 1/4 turn will fit. you may have made my mind up now though on the fuel tap as was undecided on whether to go sip fast flow or BGM equivalent. the BGM may work better for the low fuel light. and H you are right about accuracy the only time my fuel gauge is correct is when I fill it right up but 10 miles down the road it starts flapping side to side like a weeble on acid. best guide is currently when light comes on I have roughly (depends how I am riding etc) 12 miles till I have to push it!!

[sime66]

Just quickly;
ScooterCentre list the resistance ranges for the senders as follows:
Metal LML sender range 0 – 100Ω - you could check that, Hully.
Plastic PX/EFL sender range 50 – 350Ω
There’s a third PX one, but I haven’t sussed out what it’s for – 3-prong metal screw fixing, 3 wire too. 50 - 270Ω, here:
www.scooter-center.com/en/product/5250001/Fuel+gauge+PIAGGIO+PX+since+1984+metal+closure+50+270+Ohm?meta=5250001*scd_ALL_en*s19784480304704*fuel%20gauge%20sender*11*11*1*16

I’m getting 10 – 330Ω on the old plastic one I’m testing - without the arm, so that seems right. That would suggest they’re not going to work well with the wrong gauge though, but I can’t find anything to say so. In fact Beedspeed do a wiring conversion harness for LML loom to SIP speedo, so they must think LML sender and SIP speedo compatible (if you trust Beedspeed):
www.beedspeed.com/manuals/SIP%20Speedo%20to%20LML%20Instructions.pdf?osCsid=7gt2oq64enri87uc0hveqadbd1

SIP does a wired fast flow tap too for the warning light, so there's still a choice:
www.sip-scootershop.com/en/products/fuel+tap+sip+fast+flow+for_15879000

My gauge stopped swinging around a few years ago and died on me, but having done a bit of investigation here, I think it’s time to find the fault and fix it; my tank is about half-full, so a multimeter should be saying about 200Ω if the sender is working; if not I’ll pull it out and have a look……………

[hully1]

hi Sime,

Top investigative work there mate. this will give me something to consider when I purchase the other components to go with my tank.

[sime66]

I’d been meaning to suss it out anyway, and it meant I finally got round to fixing mine yesterday. It was just a broken off connection inside the body of the sender. Mine was the third type (PX metal), linked above, and worth a fiddle to fix rather than €90(SC) or £60(SIP) to replace. It’s a drag there’s three different PX/LML senders and tank fittings though; my two PX senders and tanks are different and I didn’t realize, glad I didn’t just buy a new sender anyway. Let us know how you get on with LML sender and SIP speedo later.

[hully1]

Will do Sime, glad you got yours sorted.

[pink]

Guys, my TX sender is lighting as empty on headset, but is full. Any cheap way of manipulating the sender or is it a replacement? Tried to attach a photo of top of unit, but if it's not worked, it has to white plastic blocks where wires attach on top of brass plate. Cheers....again. pink