UK Monster Owners Club Forum » .: Technical :. » Engines, Clutch, Gears » Fuel Starvation

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Old 23-12-2019, 12:02 PM   #1
Khyabusa1300
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Fuel Starvation

Hi there,

I have a 2012 Monster 796 which i am having trouble starting. Could some one tell me that if the bike has had the fuel tank removed at some point, does the bike need to be primed to get the fuel flowing, or is there something else i need to look at?

FYI both plugs are sparking and i cannot see any fault codes on the dash when trying to start.

Kind Regards
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Old 23-12-2019, 12:35 PM   #2
Mr Gazza
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796 is much later than any Monster I have experience of, but the basics should apply.
The fuel pump should fill the fuel rail upon turning on the ignition. There will be a short buzz from the fuel pump, audible with the cap open, which will stop when pressure is achieved. Then it should be good to go.
You may have the fuel pipes reversed between flow and return? although not sure if that makes any difference as the fuel rail is a loop anyway?

You could very well have a pipe pinched when the tank is lowered, this is very easy to do and somewhat hard to check with the tank down, although I have no idea how the later bikes are configured, so it's just a matter of your carefully checking what you can see.

Did you reconnect the electric supply to the fuel pump?
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Old 24-12-2019, 09:13 AM   #3
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The fuel system should self-purge/prime.
As gaza says kinked pipes are quite likely.
The pipes would have to be the right way round, as the pressure regulator sits at the return end of the rail, venting excess pressure back to the tank. If labelled: M is feed (mandata) & R return. I would expect the QR fittings to spray fuel everywhere if not properly connected, a quick wipe with grease or a squirt of chain-lube often helps ease the o-rings into place. A blocked fuel filter would also cause problems, as this is a bit of a faff to change and may be overlooked during servicing by the uneducated or lazy but should cause poor running rather than a no-start situation. If the bike turns over ok but doesn’t fire, try a new set of plugs as the 796 seems quite sensitive in this area, even if the spark looks ok when not under compression.

Last edited by slob; 24-12-2019 at 10:18 AM..
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Old 24-12-2019, 10:24 AM   #4
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Hi Mr Gazza,

Thank you for your reply. When i turn on the ignition i can hear what i believe is the fuel pump initiating which is situated to the rear of the seat. Do you think there would be some sort of error on the dash if there was an issue? Sorry for the questions but i am new to Ducati.
Electric supply to the pump? Not too sure what or where that is, but everything sounds ok as in the initiation at ignition.

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Old 24-12-2019, 10:27 AM   #5
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Hi Slob,

Thank you for your advice. I will take a look and see if any of what you said rings true.

Regards
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Old 24-12-2019, 10:45 AM   #6
Mr Gazza
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Pump is connected then.
Beyond checking for kinked or pinched pipes and that they are connected correctly, I'm afraid I have no more to offer. I can't help with fault codes. I bash two flints together at the right time for sparks!
There is a way you can check for fuel delivery by putting your finger down the inlet tract and turning the engine over with the plugs out, but it will involve an awful lot of stripping out to get there.. If you can see the electrical connectors to the injector bodies then check that they are firmly connected.

I change my spark plugs every 6000 miles, or it will get groggy.

Some 21st century boy will be along with some up to date advice, hopefully.
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Old 24-12-2019, 11:39 AM   #7
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On the EVO you just press the starter button and no twist on the throttle.
If the same as the EVO the fuel pipes are hard plastic so difficult but not impossible to kink.
Daft question you have enough fuel in the tank dont rely on the fuel light if its new to you.
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Old 24-12-2019, 02:56 PM   #8
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if you have a buzz under the seat it’s probably the exhaust valve servo, the fuel pump will definitely sound like it’s in the tank (as gaza says, try with the cap open) check the electrical connector under the back of the tank if you hear nothing, 3pin amp superseal iirc
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Old 24-12-2019, 02:59 PM   #9
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Quote:
Originally Posted by Khyabusa1300 View Post
When i turn on the ignition i can hear what i believe is the fuel pump initiating which is situated to the rear of the seat.
If you hear a whirring from under the seat, that will be the exhaust valve cycling. The fuel pump will be heard from within the tank itself. Open the fuel cap and put your ear to the tank as you turn the ignition on and you should be able to hear the pump priming.

I can't find any error messages specific to the fuel pump, but I'd have thought, if it failed, you'd see a generic ECU error displayed.

Edit: slob beat me to it!

Last edited by Luddite; 24-12-2019 at 03:04 PM..
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Old 24-12-2019, 03:18 PM   #10
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There are two other parts of the starting system that might cause problems.

Possibly the air temperature sensor is playing up and giving false readings?

Also, if the 796 is like the Evo, then there will be a stepper motor, which, according to the manual, "...defines the magnitude of the supply of supplementary air, down-line from the throttles, during the engine starting phase.

I don't know how you could check either of these components without plugging in to the Ducati diagnostics but I'd have thought you'd see an error code if they had failed.
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