Crank but no start, SPU? - MVAgusta.net
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post #1 of 27 (permalink) Old 09-12-2018, 07:35 AM Thread Starter
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Crank but no start, SPU?

No prime from fuel pump when I turn the key to the Run position. (I don't remember: Is it supposed to prime every time I turn the key to the Run position?) With spark tester on #4, I get one blip of spark every 10 or 15 crank revolutions if at all. Do you think I'm looking at an SPU problem? I have the original blue backed SPU. I've removed the tank, connected 12V to the pump wires and the pump runs. Removed the pump, no broken or disconnected hoses. Probed the pins in the connector to the pump and the bike is not sending voltage to the fuel pump.

Here's the story... It died once on the freeway the other day. I restarted and rode 20 miles home with no further problems. Next morning, cranks, but no start. Put the battery on a charger because I cranked it until the battery sounded weak. Hooked up a spark tester to #4. Initially, I was getting spark, but it seemed like it was pulsing maybe every other revolution instead of 1x every revolution. Fuel wasn't priming every time I turned the key to Run. If I waited a minute or so in between tries, it would prime. Today, I continued diagnosing and we're at the first paragraph; rarely any spark at all, never any prime.

BTW, I can't change my email address. I click Save Changes and nothing happens. Nothing is working right. I'm just going to lie down and stop breathing.
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post #2 of 27 (permalink) Old 09-12-2018, 07:45 AM
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@moocowman: again, I implore you....and everyone else...to put your bike model and year in your signature line. How can we help if we don't have this basic information?

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post #3 of 27 (permalink) Old 09-12-2018, 08:11 AM Thread Starter
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2007 910r. There. "blue backed SPU"? Thought that was sufficient.

2007 910R

Last edited by moocowman; 09-12-2018 at 08:13 AM.
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post #4 of 27 (permalink) Old 09-12-2018, 08:17 AM
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Quote:
Originally Posted by moocowman View Post
2007 910r. There. "blue backed SPU"? Thought that was sufficient.
There you go thinking again.....

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post #5 of 27 (permalink) Old 09-12-2018, 08:35 AM
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Yes, the pump should prime EVERY time.

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From the above diagrams you can see the components needed to start the bike. The fuses and relays are contained in the SPU and can certainly be suspect.

Another culprit is battery capacity, quality and condition. The ECU has a voltage cutout that will cease operation of the ECU when low voltage is sensed. This will prevent the bike system from functioning if, say during the high load of the starting sequence, voltage dips below that value.

Load test your battery.

FWIW: There are many differences between the wiring diagrams and components in the 2005/6 B4 910R/S and the later models. I'm not just being cheeky.

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post #6 of 27 (permalink) Old 09-12-2018, 08:52 AM Thread Starter
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I load tested the battery after I took it off the charger. Then, I charged it again before I ran the tests. I just checked again and now the pump primes when I turn the key to Run! But if I try to repeat it within 45 second or so, it doesn't prime. Have to wait before it primes again. Maybe that's normal? Like, maybe you can't do it in quick succession. Either way, I'm still not getting spark.

Is it correct to say if I'm getting voltage to fuse 15, the relay is working properly? The fuse is after the relay. So, if that checks out ok, what's missing is the ground pulse from SPU to the injectors and ignition coils. And if there's no pulse, the problem would be SPU or whatever tells the SPU to send a pulse, which would be crank sensor, correct?
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post #7 of 27 (permalink) Old 09-12-2018, 09:50 AM
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Your analysis is sound with one exception: The SPU is the Service Power Unit, it provides power distribution to the bike.

The ECU, Electronics Control Unit, provides the signal to the injectors after seeing a pulse form the crank position sensor pick up.

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'07 Ducati Monster S4Rs, '07 Ducati Monster 695
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post #8 of 27 (permalink) Old 09-13-2018, 06:26 AM Thread Starter
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Aw crap, forgot the SPU is not the ECU.

2007 910R
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post #9 of 27 (permalink) Old 09-13-2018, 06:40 AM Thread Starter
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Okay, am I effin blind? I can't find the power relay. I can't find ANY relays except the starting relay (solenoid). My fuse F15 is getting no power.

2007 910R
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post #10 of 27 (permalink) Old 09-13-2018, 06:48 AM
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Perhaps you are looking in the wrong areas.

I believe your relays are INSIDE the SPU....

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'07 Ducati Monster S4Rs, '07 Ducati Monster 695
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