MP3 500 no fuel and no spark questions
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Lurker
Piaggio MP3 500
Joined: 16 Aug 2019
Posts: 3
Location: San juan island, washington
Sat Aug 17, 2019 12:32 pm quote
Hello from a new forum user. I have scoured this excellent forum and learned a lot, but failed to solve my issue.

I have put 500 miles on "Loretta" a new to me 2009 MP3 500 fabled in these forums in the past. Recently I had a couple of stalls at speed, and difficult restarts: seemed electrical because turning ignition on and off a few times eventually led to restart. it always cranks over fine but without catching so a starter or voltage problem was unlikely. After quitting the fourth time it won't restart at all.

I am not near a dealer so would love any suggestions:

1. I replaced the battery though it turned over fine. No difference
2. I put some more gas in though it was half full
3. I pulled the fuel line off what I think is an injector (picture) and though it smelled of fuel nothing came out even when I was cranking the starter. I think that gas should have come out from reading the forum. I do not hear a fuel pump sound.
4. I checked both spark plug cables for spark when grounding to engine and there is no spark when I crank the engine.
5. I tried starting it with the alternate service key: no change
6. I checked all the fuses at battery compartment and right front access panel with ohm meter and they all were fine.

Immobilizer light seems to flash normally when key is off, and flashes once with two beeps then goes out when key is turned on. My recollection is that this is the same as when it was starting normally.

It is hard to believe I have both a fuel pump failure and a coil failure. I have not figured out if the immobilizer keeps the starter from cranking when it is activated, or if it just lets the engine crank without starting.

Any further troubleshooting suggestions are welcome!

Thanks, Hugh

IMG_2991.jpg
location of fuel flow check

Veni, Vidi, Posti
MP3 500, GTS 250 (both 2008 MY), 2012 Honda NC700 DCT
Joined: 02 Mar 2013
Posts: 5350
Location: Madison, Wisconsin
Sat Aug 17, 2019 12:44 pm quote
If you had that connection disconnected, and turned the key on, fuel should have poured out. Points to an issue with the fuel pump, or electrical issue causing the fuel pump to not work (blown fuse, bad relay).
Veni, Vidi, Posti
Neutrino MP3 492.7 AK, 2013 Moto Guzzi Norge
Joined: 29 Mar 2008
Posts: 21346
Location: Harriman, Tennessee, Tn
Sat Aug 17, 2019 1:38 pm quote
check ALL the fuses and not just visually actually put a meter on them and test.

fuse are under the panel by your right floorboard foot area, By the battery and the hidden fuse by the starter relay, careful to check fuse and not just the SPARE that is super easy to access the hidden fuse is under the black rubber.

Also ensure your kill switch in in the on position.
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 37493
Location: Pleasant Hill, CA
Sat Aug 17, 2019 2:28 pm quote
Best immediate guess - either a fuse or the 'injection loads relay' has intermittent contacts - not that uncommon! If all the fuses look OK, swap out that relay. Very cheap to replace. It powers the fuel pump, the coil and the injector.
Lurker
Piaggio MP3 500
Joined: 16 Aug 2019
Posts: 3
Location: San juan island, washington
Sat Aug 17, 2019 2:55 pm quote
I appreciate the replies:

Intermittent was the failure mode until it became permanent so I understand that a fuse connection could still be the issue, though it would seem that if a fuse blew it would be one time permanent.

I re-checked all the fuses near battery and right footwell with ohm meter and they are OK. I have NOT found the hidden fuse near the relay. Is it part of that relay? I attached a picture of what I am looking at.

Injection loads relay is my next search. Any help figuring out what it looks like or sourcing a replacement would be appreciated. Must be called something else too because my internet search is not coming up with anything useful.


starting sequence:


IMG_2995.jpg
starting relay? looking for hidden fuse near this.....

Veni, Vidi, Posti
2008 MP3 500, 2013 BV350
Joined: 13 Oct 2012
Posts: 7225
Location: Ashburn, Va. Home to the Internet
Sun Aug 18, 2019 8:46 am quote
Pull that brown cover off, 30 amp fuse is under that.
Look at the 4 relays under the OEM small windshield. Those are your relays except the start reply(s) under the seat. The one in the pic and one on the opposite side of the engine compartment that looks like the relays under the windshield, those both deal with engine turning over.

So just swap those other 4 around and see if the problem moves to something else
Mark them before moving so you can keep track of them, not that it really matters.
Or just take one to a parts store and ask for a replacement and move that around to see if you can fix the problem.
Lurker
Piaggio MP3 500
Joined: 16 Aug 2019
Posts: 3
Location: San juan island, washington
Sun Aug 18, 2019 4:05 pm quote
Solved! Bad relay was the issue.
I switched the two relays on the right side under the front windshield and the bike started right away! I think the far right relay was bad. Picking up a few new relays to install and have as a spare.

Thanks everyone for helping me figure this out!

Hugh
Member
MP3 ie500
Joined: 26 Jul 2017
Posts: 43
Location: Iowa City
Sat Aug 31, 2019 4:49 pm quote
Per the wiring diagram for Fucco the relay provides power for the injector, the fuel pump, and the ignition. When you turn the switch on the fuel pump should run for two seconds. If the fuel pressure is not 40 psi, the engine will start hard. Too much work for that ISO relay methinks.
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 37493
Location: Pleasant Hill, CA
Sat Aug 31, 2019 5:33 pm quote
Iowatrike wrote:
Per the wiring diagram for Fucco the relay provides power for the injector, the fuel pump, and the ignition. When you turn the switch on the fuel pump should run for two seconds. If the fuel pressure is not 40 psi, the engine will start hard. Too much work for that ISO relay methinks.
It's a 30A relay - it should be fine. However it has no quench components, and the fuel pump is an inductive load that can cause arcing at switch-off in particular. A relay with at least an internal diode across the coil would be helpful. The better ones have back-to-back Zener diodes, so there's no worries about polarity of the coil feed.
Member
MP3 ie500
Joined: 26 Jul 2017
Posts: 43
Location: Iowa City
Sat Sep 07, 2019 7:12 pm quote
the size is not the issue, its Mean time between failures. It is on for every second your motor runs and off only when you shut down. how long does it take to ride 12K miles? That's when my IsO relay failed.
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 37493
Location: Pleasant Hill, CA
Sat Sep 07, 2019 11:43 pm quote
Iowatrike wrote:
the size is not the issue, its Mean time between failures. It is on for every second your motor runs and off only when you shut down. how long does it take to ride 12K miles? That's when my IsO relay failed.
No, relays don't suffer from time related failures but it's the number of operations and the type of load that determine how susceptible they are to failure.

Switches including relays are specified by the number of operations they are designed for with given load conditions, not by MTBF.
Member
MP3 ie500
Joined: 26 Jul 2017
Posts: 43
Location: Iowa City
Sun Sep 08, 2019 12:06 pm quote
Call it what you like: load, cycle or gotterdamerung. It failed for me and loretta. Its still something you might want to check when spark, fuel and injection fail together. There are a few parts on this otherwise way cool bike that could stand some redesign.
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