Starter issues 1999 m750 - Ducati Monster Forums: Ducati Monster Motorcycle Forum

stravis · 11-24-2011, 08:48 AM

Thanks in advance for any help with a problem I'm having with a '99 m750.

It started by having to hold the starter button down for a while until the starter would engage. Now the starter does not engage ever.

I can push start it easily.

I don't have a voltmeter or anything to know exactly how many volts the battery has, but the lights are all working fine.

So I started doing some "tests" to see if the starter was bad or the solenoid. I have power to the solenoid. I have power coming from the button on one pin when I press the button. (the white connector) I don't have power when I flip the kill switch. So I assume the button and kill switch are ok.

But with it all plugged up, I cannot get the test light to light up at the starter. I can get it to light up if I jump the solenoid, from the battery side, over to the cable that goes to the starter.

I tried using jumper cables to go straight from the battery to the starter, and didn't get anything either...I should have used my car battery as well, to eliminate the possibility of a weak battery?

So right now, I'm wondering if the solenoid is bad, or the starter, or both?

QUESTIONS:

are both pins in the white connector supposed to have juice when the button is pressed? or only one?

How do you do the test with jumper cables straight from the battery to the starter? Maybe I was doing something wrong.

stravis · 11-28-2011, 01:40 PM

Anyone have any ideas or suggestions?

AdmiralKit · 12-01-2011, 11:06 PM

From the sounds of it, you've either got a bad starter or battery. The solenoid is a possibility, but the fact that you shorted out the terminals from the battery to the starter and got nothing argues against that. Get a multimeter (if you own a Ducati you can afford a cheap one from WalMart or Harbor Freight), and do some tests.

When was the last time your battery was changed? Standard lead-acid batteries only have a lifespan of a couple of years before they wear out, and it takes a lot of current to turn your starter relative to pretty much anything else your bike needs. Charge the battery, let it sit for an hour or three and test the voltage from the poles. Assuming you've got a lead-acid battery and not something lithium-based, you should read about 12.7 volts for a fully charged battery. Anything less than that can mean that you're not getting enough power into the system to make it work. If it reads below 12.5 volts, replace the battery. Otherwise, proceed to the next step.

Next step is to check the starter switch. Multimeter again - you should see two small wires coming into the solenoid and two large wires as well. Disconnect the small wires, put the multimeter in between the two wires and hit the starter button with the kill switch disengaged. You should see the meter read 12V, which would close the circuit. If you're not getting 12V there the starter switch circuit is faulty, generally meaning the switch is bad and needs replaced or there is a short that needs traced out. It sounds like you've checked this and it is probably not the case, but it doesn't hurt to verify it. If it's all good, proceed to the next step.

Now that you've checked the power that closes the solenoid, check the power flow through the solenoid. Use a volt meter on the terminal that runs to the starter motor and the other end to ground, and have a friend press the starter button for you. It should make a clunk sounds and the multimeter should read 12V when he does that. This indicates that power is flowing through the solenoid and that it is working properly. If you fail to see 12V, it means that the solenoid is not closing and thus needs to be repaired/replaced. Otherwise, proceed to the next step.

Last but not least is the starter motor itself. You've stated that you tried running the battery directly to it with no success, but that doesn't rule out either the battery or the starter motor. Check for oxidation on the starter motor power cable and clean any off if you see some. The wiring diagram says that the starter motor has a connection in from hot and then a connection out to ground, but I don't know if the ground is a second wire or just a connection through the engine back into the frame. If you've checked out the battery and verified that it is okay, try CAREFULLY using a large screwdriver across the solenoid, and be damned sure that you only touch the insulated parts. You're now bypassing the solenoid and running straight from the battery to the starter motor. If the battery checks out (or you use the car battery) and the bike doesn't start, the problem is the starter motor. If the battery doesn't pass muster, the problem is the battery. Replace/repair the appropriate part.

Johnny Business · 02-02-2012, 02:16 AM

I'm having the exact same issue. Gonna use the Admiral's advice and see what comes of it. Thanks for the great explanation. I will follow up with the outcomes.

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Johnny Business · 02-04-2012, 01:29 AM

Got all the way through and found out it's my solenoid. I have one on order from Ducati Seattle. Thanks again Admiral for the advice.

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desmoquak · 02-11-2012, 09:58 AM

I just had the same problem....when you go to turn it over will it click or just hummm. my problem was the "starter relay" the yellow relay underneath the seat, on the left hand side of the bike right next to the fuse's... hope you already have this problem resolved, but if not, then give this a try. Just to warn you, they are a little difficult to come by.
(BTW, I have a 2000 M750, and I am not sure if the electrical is different on a '99? Please, anyone who knows differently, correct me, Thanks) Godspeed....

Johnny Business · 02-17-2012, 12:26 AM

Quote:

Originally Posted by desmoquak

I just had the same problem....when you go to turn it over will it click or just hummm. my problem was the "starter relay" the yellow relay underneath the seat, on the left hand side of the bike right next to the fuse's... hope you already have this problem resolved, but if not, then give this a try. Just to warn you, they are a little difficult to come by.
(BTW, I have a 2000 M750, and I am not sure if the electrical is different on a '99? Please, anyone who knows differently, correct me, Thanks) Godspeed....

Thanks Desmoquak. The solenoid fixed my issue finally. I changed the plugs too and made sure they were set to spec. Now I'm having an air / fuel issue and the Duc is bucking more than usual. Running some Seafoam in it for a few tanks before I hit the fuel pump, filter, and (hopefully not) the carbs.

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