Modern Vespa

[url]my 2007 gts-ie 250 has blown "fuel pump fuse" on very hot day after sitting for half hour. All other systems work: suddenly it works again without blowing fuse. Very dangerous to drive. Cut cable ties check all connections. Been working fine for the first 10+ years. Is there something else on this fuse? One diagram shows something about injectors. How could they blow 10 amp fuse?[/url]

Be aware that fuses are merely very, very dim light bulbs. They do wear out.

That fuel pump fuse will take quite a high current (the onrush current that any electric motor has) until the fuel pump actually starts spinning reasonably fast.

That said, of course it's possible some wires have chafed and shorted out, or a rodent has got in there and taken a liking to some insulation, but if the bike now works then I'd put it down to an old-age fuse.

As jimc noted, a fuse element is really just a piece of wire that is sized to fail at a certain current.

For the fuel pump there is inrush current upon starting and continuous current while running. This puts that little bit of wire fuse element under stress over time plus with vibration from riding the scooter. Think of it like you would continually bend a paper clip until it failed.

It really sounds like an age related failure as when you put a new fuse in, it did not fail immediately like it would if there was a short circuit.

I would not sweat it. Ride!

I have a Vespa GT2007 GTIE that blows fuses on the fuel pump, but it says that fuse goes to the injector also.
Somehow the manuals do not seem to have an exact wire diagram where that wire goes and where it could be shorted these fuses blew on a hot day And I cannot repeat the fuse blowing if I heat it up in the garage, so I'm looking for a wiring diagram that would show the actual wires leading to the fuel pump and injector and how could the injector blow the fuse any help would be appreciated . I have seen other comments and this problem is quite dangerous. Say you might be in traffic as I was and stop dead. No other systems seem to be Involved.

It's pretty simple - the relay is on the left-hand side of the frame under the pet carrier. The output of the relay (black-green wire) then goes to the fuel pump, the injector, the coil and the lambda sensor. All visible in and around the engine.

https://manuals.wotmeworry.org.uk/Vespa/GTS250/GTS250%20Wiring%20Diagram.pdf

This 10 amp fuse blew three times.
I put an amp meter on the circuit for startup and running: not more than 1.5 amps. Did seem low.

Just look at the wires going to those items and look for a chafed wire. The lambda sensor on the exhaust is a possible culprit, that wire is more exposed than the others.

You're the one who can eyeball this, we can't.

Jimc;thanks; when the key is turned, the fuel pump turns on for one or two seconds, and then stops which it always has. Is there a pressure switch? Does it run continuously or on demand? I'm also wondering if it was replaced at one time with the recalled Chinese one starting in 2009.

My understanding is that the initial 2-second pressurising is timed, but when the engine is running the pump runs continuously. BICBW.

What is the most simple explanation:
Cannot blow the fuse the second time all the wires seem to be OK I have jiggled all of them still not blowing the on the fuel pump so it appears that the 90° outside temperature plus running for an hour and was the villain. Will get method to trailer home to feel I can use the scooter again with some confidence it won't cost a bunch to retrieve again. Saving tow charge ( $125) 2023

You did what you could to debug this. At this point I would carry a spare fuse (you probably already are doing this), and get a low-cost tow insurance plan such as AAA. Then Ride!

Get a lower cost tow plan from AMA (American Motorcyclist Association) - covers all your vehicles, and anyone else who might be riding/driving them with your permission. Only 30 miles though, but still cheaper at $60 pa than AAA's 5 mile deal...

https://americanmotorcyclist.com/

This is very helpful,

Jimjar; cut all insulation off and check for possible short; really not possible!
I'm retired industrial machine maintenance mechanic and so this probably is " best guess " repair.