Fuel Level Sender repair - Vespa PX and LML Stella scooters

I've been asked a few times on how I managed to make my Genuine Scooter Stella 2T fuel level sender reliable.  So when the opportunity to fix the sender unit on my friend's scooter came up, we decided to take photos this time.

The principle of the sender is very basic, but some of the materials chosen when it was manufactured were not ideal.  The sender works with a float on the end of a stiff wire arm.  When the float moves around the fulcrum pin, a wiper contact slides across a variable resistor.

The first step is to pry open the tabs which retain the cover over the mechanism.  It is wise not to over-bend these, because they are small and fragile.

Once the cover is removed, the mechanism is exposed.

The float goes up and down which moves a wiper contact along a nickel-chrome wire wound around an insulating material.  This forms a variable resistor.  The problem is that this insulating material is not very stiff and over time it bows away from the wiper in the middle.  When the nickel chrome wire is no longer in contact with the wiper it causes the gauge to read EMPTY.  Rather than risk snapping the small gauge nickel chrome wire and re-winding it on a different material, I have shaped pieces of non-copper-clad circuit board material into a fat "T shape" with the bottom of the "T shaped" piece 20mm wide.  The upper sides of the T are just to keep it from falling downward will be trimmed off to fit the cover back on, so I just eye them up before cutting them.  The final trim is done with a dremel cutoff tool.  If all you have is single-side copper clad board, just put the copper AWAY from the resistor.

It takes two of these to wedge the resistor back to a flat shape.  I use a file to remove some of the material of one of the T shaped pieces so they fit just right.  These aren't particularly critical, you can see I just cut them out roughly by hand using the dremel tool and didn't even bother with a straight edge.  The "T shapes" fit in from the top behind the resistor and should press down and straighten the resistor so its flat.

The resistor should be approximately 150 ohms at the empty position, and should decrease in resistance toward the full position.  If it doesn't read exactly 0 ohms when the float is all the way up, it doesn't really matter.  This one only went to 15 ohms, and worked fine when re-installed.  The video shows how we checked the operation with an analog multimeter.

Once the resistor is wedged to stay flat, the wiper stays in contact throughout the range of motion.  The cover can be replaced and the tabs gently bent back over to keep it in place.   This type of repair has lasted umpteen thousand miles.

FIAT - Eco Drive

As you know I like to drive small, that's what I like about the Imp.  "Economy" and "fun" are the name of the game.  Since I can't drive an Imp everyday, I had to have something similarly fun to drive.  Probably the most stylish and economical small modern car is the retro FIAT 500.  I'm on my second one after the first one died in a horrible crash over a year ago.

I'm one of those guys who always said "automatics are for wimps".  I haven't owned an automatic gearbox car or truck newer than model year 1983.  However, city traffic is frankly no fun with a clutch.  This was a big factor in why I chose the automatic AISIN 6-speed overdrive gearbox with auto-stick.

This presented me with an interesting opportunity, since my second FIAT is a 6-speed auto-stick, while the first one was a 5-speed manual.  The commonality is me.  Would one car be more economical to drive than the other?  The question here is that would I treat the cars the same despite the gearbox change?  Would the 5-speed manual make a more aggressive driver out of me, and would the 6-speed automatic make me lazy and drive like grandma?

I wouldn't have believed it, but the automatic is actually more fun to drive aggressively.  The sequential shift pattern shifts instantaneously when placed in manual override and even provides a little lunge to make you feel like you've accelerated  (Remember its only 101hp).  While pulling out aggressively, the torque converted won't lay-a-patch like the manual clutch would, it still gives a good visceral ride.  I'll just preface this study with the statement that I do drive economically around town and on the highway.  My commute is a fair amount of stop-and-go traffic where the manual transmission was less than pleasant in the city.  I stick to the speed limits and watch for wildlife on my daily back road trek to the office and home.  The Pop version of the FIAT 500 is base model and the least sporty of the FIAT lineup in the USA.  That all being said, I'm usually the first off the line at a multi-lane traffic light even though everyone passes me after the first few car lengths.  I don't think my driving style has changed significantly with manual vs automatic.  I get home at the same time everyday and I get to work at the same time.  I even use the manual override on the automatic about 50% of the time.

FIAT provides a data collection tool called Eco Drive. This tool collects data from your car though a USB flash drive.  The driver can then occasionally upload the data to the server where it is trended, and also compared with the rest of the FIAT driving community.  As a driver striving for economical operation, you can see where you need to improve your skills in the way of shifting, acceleration, deceleration, and general speed.  A trend of your driving habits is created and compared against the whole community average with a dimensionless value called the "Eco Index".

Here is a graph of the Eco Index of the 5-speed manual gearbox 2012 FIAT 500 Pop before its death.

TRANSMISSION: C514 FIVE-SPEED MANUAL
Description: 1st, 2nd gear: Double Cone 3rd, 4th, 5th, gear: Single Cone
Gear Ratios
1st 3.909
2nd 2.174
3rd 1.345
4th 0.974
5th 0.766
Reverse 3.818
Final-drive Ratio: 3.44
Overall Top Gear: 2.63

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Here is a graph of the Eco Index  for the Automatic gearbox 2015 FIAT 500 Pop from purchase to present day.

TRANSMISSION: AISIN AUTOMATIC SIX-SPEED OVERDRIVE WITH AUTO STICK
Description: Auto Stick driver-interactive manual control and electronically modulated torque converter clutch
Gear Ratios:
1st 4.044
2nd 2.371
3rd 1.556
4th 1.159
5th 0.852
6th 0.672
Reverse 3.193
Final Drive Ratio: 4.103
Overall Top Gear: 2.76

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Remember, this is the same model car, same fuel, same engine, same driver.  Only the gearbox is different, and the driving experience is different.  Why is the automatic consistently and significantly above average in the community?  I can't say that I drive any less aggressively, and I can't say that I have any less fun with the automatic.  The higher gear in the automatic, plus the fact that it shifts at the RIGHT time if left in the automatic mode seems to make all the difference.

Oh, and notice that when that fuel has gotten less expensive as of late, that the community has gotten less efficient, but I have increased ever so slightly!

IMP - exhaust in the cabin - fuel delivery

The major complaint from my wife is that the cabin of her car tends to smell of exhaust fumes, and makes her sleepy.  While this is a good thing to keep her from shopping excessively, it cannot be healthy for the long term.

Things we have tried include:

• Plugging all passages in the rear quarter panels above the wheel wells
• Insuring that the rear hatch seal is sealing correctly
• Taping over the vents above the rear hatch

None of these have completely cured the problem.  Putting duct tape the vents actually made it worse, even though I don't know how that would be possible.

The suggestion was made from some club members to extend the exhaust out beyond the body of the car.  This seems to make sense, but will have to be tested.  The limitation is that this car has to be able to climb up on our car trailer.  I already scrape the tailpipe as it is, so it can't get any longer.  It will have to go out the side.

I cut off the tailpipe and welded a piece of 1" EMT elbow to the stub after expanding it.  We will do some testing on this setup to insure success and the health of my bride.

The car has been known to cut out for no reason.  Even on a cold day.  I was thinking that there must be an obstruction in the fuel tank.  That turned out to be an incorrect assumption.  The tank is flawlessly clean.  I did however discover some tar-like substance running down under the fuel tank.  That was easily cleaned by using some parts washer solution and a little elbow grease.

before

after

I may investigate placing the fuel pump in the front of the car like I have on my '66.  This helps fuel delivery tremendously.... however the ticking noise of the pump can be heard from the driver's seat.

The luckiest break that I got was the clutch slave cylinder.  I was worried that the clutch had a worn friction disc, due to the juddering and grabbing that the clutch exhibited the last time the car was driven 2 years ago.  The slave cylinder was found to require a rebuild and a new hose.  Now it works fine.  We won't be pulling the engine this winter!

"Project Bantam" - Fuel Tank

The steering shaft and new gear went on without any trouble.  The ends of the shaft were a little mushroomed, but nothing a quick turn on the lathe couldn't fix.

The fuel tank was new from Mr. Shaffer.  I decided to powder coat it for extra durability. It came out looking great for a part that is not seen.  The original sediment bowl was lost, so a new Briggs-Stratton model 690612 was easily obtained.

The support straps were made from some spare stainless that I had lying about in the scrap bin.  To keep the neck from banging up the hole in the hood, I stripped some wire and used the insulation to protect the hole, by splitting it with a razor blade and fit that to the edge of the hole.  Using some silicone lubricant, the neck slid nicely into the hole.  Some inner tube rubber made a nice cushion for the fuel tank.

It looks more crooked in the picture than it actually is, because of the odd angle I had to take the photograph from.  (Don't mind my finger in the photo.)  Notice the nuts holding on the bolts onto the hood, since the original holes no longer had sufficient threads to hold the bolts to my satisfaction.

The body is looking rather finished at this point.  Considering how poor the tractor looked when it rolled into the workshop, its a ten-footer overall.  Not a show winner, but a restoration staying within a reasonable budget.

Hopefully the next post will involve some progress with the engine.

Started on 3rd kick

It was glorious!!!

I simply checked the spark, squirted some extra oil on the camshaft, and put fuel in.  It started on the 3rd kick.

KYL95 is looking good here shining in the fluorescent glow of my workshop.

Now the remaining issues...  The oil light doesn't go out.  So, I checked that with a gauge... a gauge that was too small.  It produces over 10 psi and pegged the gauge, so I'm good there.  Must be the switch, although it checked good last time I checked it a year ago.  Maybe the contacts are stuck?

I'd like to put a T in the line and monitor the oil pressure with a permanent gauge.  Anyone know what kind of thread that is?  Or should I go back to Stewart Engineering and get the adapter and a modern oil switch?

Second issue.  The charge indicator stays on, which indicates more trouble.  I'll try checking the case ground and then tickling the field coil again and see if that does anything.  I recall having an earthing issue on the dynamo casing when I first started working on the bike back in October.  There is the chance that the voltage regulator isn't working right, but that will take some time to debug.

Overall I'm very happy.  It starts amazing easily.  I didn't let it warm up properly enough to turn off the strangler.  That will be the real test, because before it popped and chugged and carried on like crazy before with the old loose & leaky throttle slide.  This new throttle slide is a little on the tight side... The return spring BEARLY overcomes the friction to close the throttle.