Modern Vespa

Just in the process of refitting the fuel tank on my LML after a change of cables (inc. outers). I can't for the life of me get the tank to drop fully back down into the frame. I'm not talking about the fuel lever and sight glass, they go in fine. It's the last half an inch that doesn't seem to want to go down. I can't see anything obvious that's different from before that could be blocking the way. Any ideas?

fuel line grommet is backwards. the line should exit pointing towards the carb, so its a straight shot from grommet to carb

I like your lining on the frame inside. How did you do it?

Great, hopefully that will solve the problem. I couldn't remember which way round it went when I replaced it so I chose the way that seemed to align best with the pipe as it entered the grommet, inside the frame.

It came like that from the factory. Not sure of the reason, maybe it cuts down the engine noise a bit. The cowls also have a sound-deadening lining. It certainly makes an area that's already tight for space even tighter. And it doesn't make cleaning up after a leaking oil tank any easier. Thankfully the foam seems to be better quality than the rubber parts, otherwise there'd be chunks of it in the carb box.

I spent over an hour triong to get a Stella tank back in and ended up removing some of that foam.

Back at it again today but still no luck. I've reinstalled the fuel pipe grommet the correct way round but there's still something stopping the tank dropping the final half inch. I'm sure I could get a few threads started on the M8 bolts and crank then ratchet the tank flush but it doesn't seem right.

The only change I've made is replacing the cables, so that's what I'm focusing on:
1. Does the choke cable loop round under or over itself? I've got it going over, which seems the most direct route.
2. Likewise the throttle cable - should it go under the tube where the choke cable attaches, or over it? Again, over seems more direct but encroaches on tank space slightly.

Perhaps your fuel line clip is improperly installed, but is not visible in your photo. My PX150 never came with the fuel line clip since new. The fuel line came around the side of the oil tank and then under it, just in front of the oil feed fitting.
That is the deeper part of the frame cavity, which gives the fuel hose a gentle curve while avoiding getting pinched.

Sorted! It was one (or a combination) of two things:

1. I rerouted the choke cable so that it looped under itself. I did the same with the throttle cable. Basically, both cables now loop under the choke tube, leaving the choke cable as it exits the tube being the highest point in that area.

2. I noticed some scratching on the edge of the plastic tray at the bottom of the tank cavity. This seemed to line up with the clip used to attach the oil pipe to its spigot at the very bottom of the tank assembly. I turned the clip through 90 degrees so that the protruding parts were no longer pointing down, thereby gaining a couple of mm.

Tested fuel flow as well as throttle and choke operation - all OK.

I know I should've taken some pics but I didn't and I'm definitely not going to pull the tank again to get some!

Can't believe what a huge pain in the arse this has been - I must've had tanks out on various scooters a dozen times and (apart from the usual fuel lever shenanigans) never had a problem before.

Time for a beer

The Stella also has the "engine diaper". It's a plastic cover lined with foam that goes over the gearbox portion of the engine. Presumably, it's to reduce noise, but I would imagine that it would soak up a fair amount of oil over time.

Nothing wrong with any of it. I removed it from the frame tunnel because it was soaked with oil. A couple of dead and oil soaked mice found in the frame had made the oil line their last meal.

Same with the UK-market LMLs. I bought mine new in 2009 and that cover was removed at the first oil change, never to reappear.

I just did this same job over the weekend on my 200. Fought with the choke cable and clip for ages before it would work. The choke clip kept popping off until I bent it to work better.

The 200 doesn't have the bracket for the fuel line on the bottom of the oil tank which might make it easier to fit. I always have more trouble with the Stella tank and site glass although the last time it went well. Every little thing on this 200 has been kicking my ass lately.

The frustrating thing about Vespas is that something you've done 10 times with no trouble can have you going in circles on a different day for no apparent reason. I had the tanks and lines all in when the friction clip popped off…again.🤬