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2000 Monster 900ie, 1993 750 Supersport, 1948 Velocette 500 MSS
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Discussion Starter #1
A couple of days ago the above mentioned bike started to run on one cylinder. I checked the plug wires and they seemed ok so I changed the plugs. I was about to check for spark with a plug in the front (non firing) cylinder and the starter motor did nothing. I charged the battery to full charge, still nothing. I checked the wiring to the solenoid and cleaned the connectors, still nothing. I checked the main relay, the fuses including the charging fuse and the injector fuses, all good.
ECU?
If it's the ECU, are there options to replace it with a fully programable unit that will accept an O2 sensor?
 

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Check the sidestand switch isnt stopping the pump priming. There is a connector next to the tps sensor on the left of the bike. Just wrap some copper wire around the pins in the upper half of the plug to by pass the Sidestand switch. The kill switch on the bar can also cause the same problem. So open it and check it out.
If the pump then primes, thats step one.
Then i would swap the coils to see if the other cylinder then doesnt run.

Are you confident using a multimeter?

If you can, order a set of ODB Cables from LOnlec and download GUZZIdiag (its free and the cables cost about 25). Then you can read any fault codes.

Start there
 

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2000 Monster 900ie, 1993 750 Supersport, 1948 Velocette 500 MSS
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Discussion Starter #3
Ha Ha! I didn't think this bike had a sidestand switch but someone took it off the sidestand and stuffed it under the tank. I couldn't figure out what it was... it kinda looked like it may have been another TPS, but not really. Yup. I just repositioned the tab and the starter motor now works again. Yup. I'll try the coil switch next. Btw, yes I can use a multimeter, scope, signal generator, etc.
Thankfully it's not likely the ECU although I really want to lose the airbox and use a lambda O2 sensor to richen things up afterwards.
 

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2000 Monster 900ie, 1993 750 Supersport, 1948 Velocette 500 MSS
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Discussion Starter #4
Actually, I think I'll start by comparing the DCRs of the primary and secondaries of the coils. I seem to remember my supersport coils were supposed to be 4 or 5 ohms on the primaries and 12 to 15 k for the secondaries. Btw, can a 2000 use a low DCR primary (0.3 Ω) ?
 

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2000 Monster 900ie, 1993 750 Supersport, 1948 Velocette 500 MSS
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8 Posts
Discussion Starter #5
Well, there's a good strong spark on the front cylinder and the DCRs look fine. Must be an injector issue.
 

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I think the last time i tested mine it was 5K and 18K for Primary and secondary windings. It could be an injector but they are fairly robust. Easy enough to clean and cheap enough to replace.
I bought a 2000 M900Sie at the beginning of this year and ended going through EVERYTHING because it ran like a bag of nails. In the end it was lots of things, dead fuel pump (only 1 bar of fuel pressure) and Valves that needed to be reground were the main culprits.
I cant recommend the Lonlec Cables and Guzzi diag enough. You can adjust the CO Trim with it and upload different maps with relative ease. I have the Ducati Performance map on mine and it richens up the "emissions" area and gets rid of all that airbox popping and the motor pulls clean and hard from 3K. You might find you dont need o2 sensors. If you want to go that route i think SeriousBlack on the Ducati MS froum did some datalogging with a wide Band o2 sensor and he'll be able to point you in the right direction.


this my "problem thread" there is a pik of how i cleaned the injectors, a 9V battery will fire them, make sure to do it intermittently so as not to overheat the solenoid.
 

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2000 Monster 900ie, 1993 750 Supersport, 1948 Velocette 500 MSS
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Discussion Starter #7
Thank you Chris. I just finished reading the complete thread (the link sent.) What an ordeal! In your opinion, could a bad fuel pump cause just one cylinder to not function?
I may not have stated earlier that the bike was running fine and all of a sudden started running on the vertical cylinder only. Since it's got spark, it must be a fuel issue. The pressure regulator would affect both injectors. Might low fuel pressure affect one cylinder / injector if the injectors were buggered up unequally? The PO said he used only alcohol-free gas.
I started tearing down the airbox yesterday afternoon and found that mice had been in there... chewed up filter and seeds etc. All soft stuff though.
 

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If one cylinder is running as it should i would think - and I'm not an expert just a hobby mechanic - that its unlikely to be be the pump, filter or regulator. Chaging the filter and hoses is cheap and good house keeping so id do it anyway.
But if your bike has "Guests" I'd be checking for continuity from the injector to the ecu.

The lovely thing about these bikss is the simplicity of the injection system, there really is very little to it and most of the parts are cheap if you source a part from magnetti marelli via their part number thst was also used on a fiat or alfa. E. G. The crank sensor from Ducati is 240 euro, thr same fiat part (with a 5cm longer wire) is under 20 euros and works a treat.

I redrew the m900ie wiring diagram and seperated the systems on to different pages of pdf. Charging/lights/ie etc. Ill dig it out and post it here. If you chase down the continuity with your multimeter you might find the issue and its acheap fix. With the cost being some maus traps. :)
 

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2000 Monster 900ie, 1993 750 Supersport, 1948 Velocette 500 MSS
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Discussion Starter #12
Thank you Chris!
I replaced the injectors, cleaned all the electrical connectors, cleaned the throttle bodies, new plugs, and the thing runs fine. BTW, I removed the sidestand switch and both connectors and connected the two wires together.
Next jobs will be to remap the ecu.
Is this the proper connector set?

225642
 

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That's great news! Glad it runs well again.
Yes thats the correct cable set. Download the two GuzziDiag applications and you are good to go. If you want to try the Ducati Performance map i can send it to you via Email or Dropbox.
Its a setup for Slip-On exhaust cans and the open AirFilter Lid with a K&N or similar element. It also does away with the lean area that is used for emissions homolgation.
Just read the stock map first and save it, just in case.
 
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