Rough running after fill-up

[dsquare]

Out of nowhere - for the past several fill-ups - my 2001 1100RT runs very rough and will stall if I don't keep the RPM's up. After about 10 miles it settles back to normal smooth operation. Bike has 56k miles and I have not modified my tank filling proceedure. While I usually fill it to the very top while seated on the bike, last time I tried to leave about an inch of empty space on the top of the tank. Same result - bike surges and stalls if not given gas. I have a Techlusion on the bike but doubt it's the cause. Any thoughts appreciated.

[Wooster]

I'm a bit confused. Is the rough running/stalling happening only with a cold motor ? ("After about ten miles it settles back to normal...") And, this rough running/stalling, has it been happening for several weeks ? ("for the past several fill-ups")

If so, given the bike's 56K miles, well, it's possible that the throttle bodies have crud (sure bad gas can excacerbate this yet age/miles usualy is sufficient to accumulate crud). I had the same issue (with cold motor) and found fuel injection cleaner, e.g., techron, helps rectify problem.

 

Wooster who identifies with your avatar (if that's glacier green metalic)

[dsquare]

When I fill-up, my motor is at normal running temp. I'm careful to use only top tier gas with an occational application of Techtron. The engine, in my opinion, is in perfect tune. This problem only occurs for a few miles after a fill-up. Before and after it runs normally. Thought I might have overfilled (topped)the first time - remember reading somewhere that that is not a good idea - but now it happens everytime for the past 4 consecutive fill-ups.

 

Actual color is Opel Blue.

[flat_twin]

Just a WAG but it sounds like a ventilation problem. Was the tank removed or lifted recently? Is there gasoline in the vent tubes going to the charcoal canister?

 

My only other thought is it has to do with the fresh fuel agitating the inside of the fuel tank when you fill up.

[11101110]

Is this happening with fuel from the same gas station?

[4wheeldog]

Just a WAG but it sounds like a ventilation problem. Was the tank removed or lifted recently? Is there gasoline in the vent tubes going to the charcoal canister?

 

My only other thought is it has to do with the fresh fuel agitating the inside of the fuel tank when you fill up.

 

+1. The most likely problem is you have a pint or so of water sitting in the bottom of the tank. Every time you fill up, the water gets moved around and some settles into the fuel pump cavity. Once it is resettled, the bike runs OK.......Until you mix it up again.

 

I had this very same problem, solved by siphoning 1/2 gallon of fuel from the very botton of the tank. That may not get it all, but it got enough of it for attrition to get the rest. Good Luck.

[T__]

dsquare, that is a strange one.. It does sound a bit like water in the tank but you would think that after a few fill ups it would be run through the system by now.. The fuel system has a return line so the fuel in the tank stays pretty well stirred up.. As a test,, when the tank gets a little low on fuel shake the bike side to side to see if that makes it run bad..

 

It might be something to do with when you open the tank cap at fill time.. Again,, as a test,, just stop the bike (hot),, then open the tank cap for a few minutes (like you filling the tank but don’t add gas).. Again see if it runs bad.. (do you hear a whooshing sound when you open the cap?)

 

How about if you make the stop for fuel- only don’t add any? Just turn it off & let it sit for the same amount of time.. If it then acts up suspect the Techlusion first,, (moisture in it (the Techlusion) will sometimes make them act like yours is doing).. This is especially true if you have the older style Techlusion with the removable cover to program it.. If you suspect the Techlusion just disconnect the injector tie-in connector in or MAYBE just try removing the Techlusion ground wire (just turning it (the Techlusion) off isn’t enough)..

 

Or,, if it still acts up after the stop without adding gas possibly suspect he HES sensor (down the list but possible)..

 

 

Do you do anything different ONLY at fill up time?

 

 

Twisty

 

[David R]

Possible EVAP system problem like a soaked charcoal canister. Easy way to tell is unhook it and plug the tubes on the carb for one tank of fuel and see if it goes away.

 

Just my guess.....

 

David

[4wheeldog]

This is exactly what my '02 did with water in the tank. I know it would seem reasonable that a couple of tanks would absorb it, but that was not the case. Again, just siphoning out the bottom of the tank seemed to address it. I could actually see the water in the plastic gas can. I just put all but the obvious water in my truck. Poured the rest into a pan to evaporate.

[vizhip]

It does sound a bit like water in the tank but you would think that after a few fill ups it would be run through the system by now..

 

If he always fills up at the same place... it could be that they have water in their tanks... and maybe he should try filling up at another service station...

 

Regards -

-Bob

[David R]

Sunoco fuel has 10% methanol ethenol?..... alcohol. Fill up once a month and the methanol will absorb the water. Mileage may suffer a little.

 

David

[spfksfdk]

I had uneven running at high revs and it sometimes seemed to be worse after filling up and also for the first few miles.

 

After £900 of garage bills it turned out to be a dodgy injector. I got a second hand one for £20 (from MotorWorks), swapped one side then the other and it runs fine. Few weeks ago I had the same fault, so I swapped the other, fixed.

 

It maybe nothing like your fault, but thought I'd drop it in.

 

[Selden]

Sunoco fuel has 10% methanol ethenol?..... alcohol. Fill up once a month and the methanol will absorb the water. Mileage may suffer a little.

 

David

AFAIK, the only alcohol added to U.S. auto fuels is ethanol. Methanol is sometimes used as a racing fuel, but it's much more corrosive than ethanol. Either tends to absorb water, but not in huge quantities. If water contamination is suspected, I would drain the tank.