Won't Restart When Hot (Not FJRF011)

[K_Flyer]

Both our bikes have recently had problems restarting when hot. Normally you just tap the button after going through the entire turn-on sequence and the engine fires up immediately. Typical failure scenario is -- stop for gas after an hour or two of spirited riding, fill the tanks, key on and wait to be through the sequence (and reset the trip timer). Press the starter, the engine cranks over but does not fire. Open the throttle to try again and zoom! At least half the time, both bikes will have the same problem. It's not related to refilling the tank as the same thing has happened when we stopped for five minutes to wait for a ferry. Both bikes were serviced about 3 k ago just before we left home. Temperatures were in the mid 80's to mid 90's, elevations 2 to 4 k '.

Yes, I did a search (starting in NEPRT) but could not find anything relevant. Also did a general Google search which described more the case where the bike had not been run for a while.

Ideas?

 

[RossKean]

If the bike is sitting for a little while, you might be getting enough gasoline fume into the charcoal canister (CA bike) to make it run very poorly or be reluctant to start at all. Doesn't sound like that's the issue since you mention the stop isn't extended. Perhaps you are overfilling a bit? In a 49 state bike, the overflow goes to the ground - does it go to the canister on a CA bike? If so, try to avoid overfilling and see if it improves. That could explain the gas stop but not the ferry stop. Other than that, I don't have any suggestions. Not a common issue and it is happening to both bikes???

 

[eflyguy]

There's really no reason for fuel to be going anywhere when the engine is turned off, because the injectors will be closed. It's a pressurized system, so it's not like it's leaking out a little here and there..

I also can't imagine it being a lack of fuel, because the pump gets the system up to pressure in just a second after turning the key on. Heat-related increase in pressure would mean more fuel for similar injector opening duration.

.. which has me wondering - is there possibly too much pressure causing flooding on that initial attempt to restart? Is there a relief valve that allows fuel back into the tank?

(goes looking for service manual.....)

 

[rogdeb]

Both our bikes have recently had problems restarting when hot. Normally you just tap the button after going through the entire turn-on sequence and the engine fires up immediately. Typical failure scenario is -- stop for gas after an hour or two of spirited riding, fill the tanks, key on and wait to be through the sequence (and reset the trip timer). Press the starter, the engine cranks over but does not fire. Open the throttle to try again and zoom! At least half the time, both bikes will have the same problem. It's not related to refilling the tank as the same thing has happened when we stopped for five minutes to wait for a ferry. Both bikes were serviced about 3 k ago just before we left home. Temperatures were in the mid 80's to mid 90's, elevations 2 to 4 k '.
Yes, I did a search (starting in NEPRT) but could not find anything relevant. Also did a general Google search which described more the case where the bike had not been run for a while.

Ideas?

Sounds like the bike has the same problem that some of the Gen 1's had -- mine anyway. Same conditions as you describe.

Once mine started (WOT) it then ran like it had fuel starvation for the first 30 seconds or so.

Ionbeam (Alan) once came up with a plausible answer, which I can't now remember

--- hope he reads this and can enlighten you.

 

[rbentnail]

Some of our Gen2's would do this, too. The work-around (I still do it this way after 100k+ miles) is to hit the engine kill switch then turn on the key, then wait 5 or 6 seconds then turn kill switch back to "run" and start bike. It is like the cycle of the fuel pump is sometimes too much fuel when the engine is hot.

 

[roger dodger]

Fast starter syndrome (FSS) is TOO MUCH gas flooding the engine... lost compression.

This sounds like fuel starvation... maybe boiling it dry in hot FI tubes... fuel pump or ???

I try to let it rest a bit before shutting it off hot. At gas stops or home I run at idle for 10 - 20 secs then use the kick stand ( or kill switch). ( I had a drop due to rolling (not in gear)).

Then restart w/ clutch in ... or in neutral. Let it idle 10 - 20 secs to stabilize idle and circulate oil, coolant, and cool fuel.

 

[K_Flyer]

Some things to try. Since both bikes have the problem, Theresa will try the rbentnail approach and I will try the roger one. Of course, for a real test, we need a third bike as a control.

Heading out tomorrow morning after two days visiting relatives in Idaho.

 

[Constant Mesh]

Fuel injection during startup is affected by coolant temperature. The primary injection compensation variable during start-up is coolant temp.

When you shut down a hot engine the coolant temperature at the sensor continues to rise for a short while since coolant flow has abruptly stopped.

If you try to restart after a brief shutdown of less than ten minutes or so the coolant temp can often be quite high, enough even for the fan/s to start at key-on.

I would speculate that the fuel injection during start-up may be greatly affected by that high coolant temp. I'd assume higher coolant temps would lead to reduced injection at start-up.

From my experience on the Gen I, a hot start-up after a brief shutdown stresses the starter motor more than any other scenario. But that may be a totally separate issue from what is being described in this thread.

 

[HotRodZilla]

Are these California bikes with charcoal canisters?

 

[RossKean]

Are these California bikes with charcoal canisters?

I assumed so based upon the OP's location and the fact that the bikes are fairly new, but a few minutes isn't long enough to saturate the canister with gas fume. (That was my initial thought.) That usually takes some time in direct sunlight (my '07 is a CA bike even though I bought it from a guy in Connecticut. I had occasional problems with that!).

 

[K_Flyer]

Are these California bikes with charcoal canisters?

Yes.

Had about 4 hot restarts on each bike today. Despite our best intentions to try some of the ideas, we just tapped the start button and they fired up smoothly. Maybe they don't like fuel measured in liters.

 

[K_Flyer]

Arrived home late on the 5th with no restart problems with normal startup procedure.

I used to consult in equipment reliability, mostly hardware. It was always frustrating when a problem cured (or appeared to cure) itself.