Extremely long crank time to start (only once!)

[krist0ph3r]

Had a perplexing and unnerving problem today: my 2002 ST1300 which usually starts in a second, started after what felt like a minute of cranking! Fuel pump primed when ignition switched on, nothing amiss when cranking (battery barely a month old so cranked at full speed all the while). Once started it ran normally - rode it 5 different times today after the initial issue and started and ran as normal after the first incident. No fuel smell/smoke etc when cranking or when idling/lightly revved after it started.

The bike had a full tank of fuel after it was last ridden for 100 miles or so last Saturday, filled from my usual pump which I've never had issues with (regular E10 unleaded). No additives etc.

After the first crank of 10 seconds or so when it didn't start, I opened and closed the tank lid to eliminate the possibility of vapour lock, but that didn't help.

The kill-switch has never given trouble (I avoid using it). Stand switch has never given trouble either and works as expected. Never tested the tilt/tip over sensor (if the ST1300 has one!).

Bike was in neutral, on the side stand. No warning lights etc when cranking or after it started/while riding.

Thoughts?

 

[SMSW]

My bike used to crank for maybe 10 to 20 seconds the first time I started it in the spring. It seemed like forever before it fired. After that, it lit up on the first revolution all summer. My VStrom and NC750 show no such behavior, firing instantly.

I wouldn't worry about this unless it happens again. From posts by @Uncle Phil about his 1100(s), this might be the beginning of a fuel pump failure (just a wild eyed guess).

 

[krist0ph3r]

Thanks - I should add by way of history, I've regularly had the bike parked for upto 8 weeks with no issues. Would keep stored fuel to a minimum (2 bars on the guage) and it would start in under 10 seconds. Any starting problems after keeping it parked for a while would be due to the battery draining. Today it was neither as the crank speed did not drop throughout, and the bike was only parked a week (I'd rarely ride it more than once a week anyway!).

 

[SMSW]

Would keep stored fuel to a minimum (2 bars on the guage) and it would start in under 10 seconds. Any starting problems after keeping it parked for a while would be due to the battery draining.

FYI, I've read a number of times that when storing a car for the winter (or a bike) you should fill the gas tank to prevent condensation from forming in the empty space above the fuel. I usually add Stabil to the tank a few weeks or a month before the last ride (and add more w/ any subsequent fill-ups) but that's my preference. It is also a good idea to put the battery on a maintainer (I like the Optimate) for winter storage.

 

[Andrew Shadow]

I had two initial thoughts. The first is that the fuel pump is on its way out. The second is that the check valve that maintains the fuel rail pressure is leaking down.

Fair warning- I have never had a need to look in to the ST1300 fuel system that deeply to know if that check valve is in the fuel pump assembly, the fuel pressure regulator assembly, elsewhere all together, or it doesn't have one at all. Someone on here will probably know.

 

[Nightmare]

I had two initial thoughts. The first is that the fuel pump is on its way out. The second is that the check valve that maintains the fuel rail pressure is leaking down.

Fair warning- I have never had a need to look in to the ST1300 fuel system that deeply to know if that check valve is in the fuel pump assembly, the fuel pressure regulator assembly, elsewhere all together, or it doesn't have one at all. Someone on here will probably know.

If it was the fuel rail leaking, that should be negated by the pump priming before cranking, otherwise the bike should be running poorly due to a lack of fuel pressure.

 

[Andrew Shadow]

If it was the fuel rail leaking, that should be negated by the pump priming before cranking, otherwise the bike should be running poorly due to a lack of fuel pressure.

Not necessarily. If fuel pressure in the fuel rail drains down to zero this could cause an increase in cranking time if the fuel pump priming process was not allowed to complete before attempting to start the engine. If the start button is pushed immediately the fuel pump may not have time to build the pressure back up to the required minimum level. Additional variables like any fatigue in the fuel pump, increased resistance in the fuel filter, weak battery, could exasperate what would normally not be a problem.

 

[krist0ph3r]

Not necessarily. If fuel pressure in the fuel rail drains down to zero this could cause an increase in cranking time if the fuel pump priming process was not allowed to complete before attempting to start the engine. If the start button is pushed immediately the fuel pump may not have time to build the pressure back up to the required minimum level. Additional variables like any fatigue in the fuel pump, increased resistance in the fuel filter, weak battery, could exasperate what would normally not be a problem.

Yeah I always wait for the pump to finish priming and all dash lights (other than neutral of course) to go off before I hit the ignition button. Pump priming time was normal.

Anyway, problem hasn't repeated so It's filed away for later, fingers crossed it doesn't recur on a day I really need it to work!