[db1911]

So, I went out to go home from work, and my ST4S won't start. I hear the fuel pump when I switch the key. As usual, I wait for the ECU to set and DUC ST to flash on the display, then I hit the starter. It acts like it wants to start, then dies out immediately. The thing is, once the ECU sets, I can't hear the fuel pump. If I switch it off, then back on, I hear the pump again up to the same point, then nothing.

No problems riding to work this AM, but it doesn't look like I'm riding home. It is 105 outside right now, but I haven't had any problems this week, even on hotter days. Is there anything that I can check, wiggle or otherwise coerce to get fuel flowing again? Assuming, of course, that's really my problem.

Anyone have experience with this issue?

 

[grimah1w]

105F. You probably don't want to try bump starting but if you can find a grade or some willing Arizonans to push you, you may get a start and also narrow your search of culprit to selonoid or starter. Selonoid or even more probable the plastic connector on back side of it...right side fairing removal needed to access it...which means mirrors and nose fairing off too...giant PITA especially in 105F heat. BTW, The fuel pump cycle you describe sounds normal.

 

[jssport]

It could be the in-tank fuel line has come off the fuel pump.


Look in the tank and turn the key on, you'll see the gas pumping up if that's it.


There is no pressure sensor/regulator that turns the pump on/off. The fuel pump turns on for a preset amount of time when you turn the key on, then stays on once the motor starts.

I've gone through this exact scenerio, ......


I thought since the fuel pump shut off, my lines must be good, it wasn't so.

LT's latest 4v book also makes this incorrect assumption about fuel line pressure shutting off the pump. ... we've talked ....

 

[db1911]

105F. You probably don't want to try bump starting but if you can find a grade or some willing Arizonans to push you, you may get a start and also narrow your search of culprit to selonoid or starter. Selonoid or even more probable the plastic connector on back side of it...right side fairing removal needed to access it...which means mirrors and nose fairing off too...giant PITA especially in 105F heat. BTW, The fuel pump cycle you describe sounds normal.

I should have been clearer in the OP. The starter turns over just fine, it's just not getting fuel or fire. My suspicion is fuel, but that's only because I don't hear the usual fuel pump noises after I begin the start up sequence.

 

[db1911]

It could be the in-tank fuel line has come off the fuel pump.


Look in the tank and turn the key on, you'll see the gas pumping up if that's it.


There is no pressure sensor/regulator that turns the pump on/off. The fuel pump turns on for a preset amount of time when you turn the key on, then stays on once the motor starts.

I've gone through this exact scenerio, ......


I thought since the fuel pump shut off, my lines must be good, it wasn't so.

LT's latest 4v book also makes this incorrect assumption about fuel line pressure shutting off the pump. ... we've talked ....

I opened the tank and tried to start again. I didn't see any movement of fuel in the tank. Does that mean the line's probably attached?

If I understand what you're telling me, the fuel pump normally comes back on once the bike starts. I get ignition, just not enough to sustain starting, so perhaps there isn't enough fuel there to start, but the fuel pump isn't going to come back on until the bike starts.

 

[pgeller]

Can you pull a spark plug to see 1) if it is wet with fuel and 2) sparking when plugged in and grounded against the head? It might help narrow the causes.

Typically, even with a split fuel line, it will run a bit, just not sustain high fuel flows. Some folks have found split fuel lines in the tank without seeing any real swirling. If they've never been changed, they are going to fail. Dig in!

pg
DD

 

[SS904]

Pump cycles on when you turn on the key and then shuts off after a few seconds, as has been noted. When you press the starter button, it should come back on. You can check this with a volt meter at the plug under the tank across pins 1 and 2 (BRN/WHT and BLK).

If you hear the pump at "key on" and the starter motor is turning over, my guess is the electronics associated are fine. Injection relay, fuel pump, ECU, kill switch, side stand interlock all should be good. Kill SW and side stand interlock would prevent the starter form turning the engine and the other stuff mentioned would keep the fuel pump from running.

You could squirt a little starter fluid down the TBs and try to start it. If it catches or coughs, you know it's a fuel problem. If it does nothing, but you maybe smell fuel from trying to start it, then it's a spark problem. If it does nothing and you don’t smell fuel, possible ECU? If you open the throttle with the air box lid and filter off, you should see fuel spraying from the injectors when you hold the starter button. You could also check spark the "old fashion way" by holding a plug, connected to a plug wire, to ground. Just don’t hold it there with your hand! Rear cylinder would be easiest to check.
Checked the fuses?

 

[grimah1w]

When you place the key in the ignition and switch to on psition, the pump relay activates and the pump drives for about 3 seconds, you may see a ripple on surface of fuel if tank is full and cap open. At about 3 seconds, you will hear fuel pump relay click again, turning the fuel pump OFF. At some point after cranking and engine ignition, the fuel pump will recontinue it's job of providing pressurized fuel to the injectors...

As to why yours doesn't start, from your OP, I misunderstood and thought your starter was acting intermittent, if the starter continues to engage when the switch is pressed, you may be looking at fuel delivery issue, split hose in tank, clog in line or filter, possible injector issues, etc.

Any smell of fuel in exhaust, i.e. Uncombusted fuel?

 

[jssport]

So DB1911,


Don't leave us hanging here bud, what have you found out ?

 

[db1911]

Since the bike was at work and I am without a garage until August , I ended up having a local Ducati shop pick it up yesterday. They said on the phone this afternoon that the battery was bad and they're checking the charging system. I'm surprised since the starter turned over fine. Guess I'll reserve judgement until I get the bike back. I hated to send it to the shop. It's not my style, but circumstances are what they are.

I couldn't detect a fuel smell and figured I was gonna have to go into the tank...

Anyway, I'll let you know what turns up.

Sent from my HTC Vision using Motorcycle.com App

 

[RedST]

Since the bike was at work and I am without a garage until August , I ended up having a local Ducati shop pick it up yesterday. They said on the phone this afternoon that the battery was bad and they're checking the charging system. I'm surprised since the starter turned over fine. Guess I'll reserve judgement until I get the bike back. I hated to send it to the shop. It's not my style, but circumstances are what they are.

I couldn't detect a fuel smell and figured I was gonna have to go into the tank...

Anyway, I'll let you know what turns up.

Sent from my HTC Vision using Motorcycle.com App

Did it start once the temp outside dropped? Possibly vapor lock at 105ºF.

 

[Rovichris]

Did you recently fuel up on your ride in? This is what usually leads to a fuel line popping off, or at least did on mine.


Sent from my iPad using MO Free

 

[tonered]

Did you recently fuel up on your ride in? This is what usually leads to a fuel line popping off, or at least did on mine.


Sent from my iPad using MO Free

^^^^^^^^^ This. I don't know why, but the three times mine popped (all my fault), it was with a full tank.

Have a good one.

 

[jssport]

So DB1911, what was it ?

 

[Mike]

So DB1911, what was it ?

Sounds like it was a battery with a bad cell. Enough juice to crank the starter but not enough voltage to keep the ECU happy.

If it has never been done, this would be a good time to clean up the ground on the engine case and maybe replace the cables if they've seen better days.

 

[db1911]

Sorry to leave everyone hanging. I was out of town for a couple of weeks with very limited net access.

Good call Mike. The battery was the culprit. Fuel lines pump and pressure, spark and starter all checked out. The charging circuit also checked out. I wouldn't have guessed that the battery could be strong enough to supply the starter but not the ECU. Nevertheless, a new battery brought everything back to normal.

Definitely learned something new. Hopefully I'll recognize the symptoms next time. Batteries typically don't last very long here from what I've been told.