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[SE-Mike]

I have an 05 Fatboy that had been sitting for a couple months and it was fine when I parked it in the garage and hooked the battery tender to it. I finally got a chance to take it for a ride and its not running right. It idles good and runs good below 3500rpm, but above that it just falls on its face and wont excellerate. It seems to run better when cold and the hotter the engine gets the worse it runs at high rpm. I thought it may be bad gas, but with about a gallon of fuel left in the tank I filled it back up with fresh stuff and it's still the same. I pulled the plugs and they look great, I've checked electrical connectors and everything looks good. The bike has less than 10k on it and I'm not sure what to look for next.

Any ideas on this I would appriciate.

Mike

[gordy]

Fuel injected or carb'd?  If FI'd maybe fuel pump, filter or perforated internal hose.

[SE-Mike]

Fuel injected or carb'd?  If FI'd maybe fuel pump, filter or perforated internal hose.

It's fuel injected, and I thought about what you said as a possibility, but why would it run better when it's cold?

[grc]

If you stored the bike for the winter with gas in the tank, and didn't treat that gas with stabilizer and/or run all the fuel out of the injectors and fuel rail, there's a good chance that you have one or two partially fouled or sticking injectors.  The same principle would apply to carb bikes, btw.  Fuel sitting in the injectors, or jets in a carb, evaporates over time and leaves a varnish like material.  Easiest first action to take would be to pour some injector cleaner into the fuel (don't go nuts, use the amount specified per gallon on the container, not the entire can) and ride it at low speeds where it seems to run OK.  If it's a little varnish buildup, the concentrated cleaner should either clear it completely or at least clear it enough to verify that was the problem by the time you use up that tank of fuel.  If it helps but still doesn't completely correct the problem, it's fairly easy to remove the injectors and have them bench cleaned.  Even the typical Harley dealership should be able to handle it.

One reason it might run OK cold and progressively worse as it warms up could be that the injectors are sticking and leaking extra fuel into the intake.  Extra fuel is OK when the engine is cold, and in fact is required for starting and decent warmup.  Once the engine gets warmed up, however, excess fuel will make the engine blubber and run like crap.  If it runs way too rich, you may notice black smoke from the exhaust.


Jerry

[hdbrad03]

What is the mileage on the Bike?

 
     Brad

[StrokedRider]

If the Injectors do not "Spray" efficiently due to either low fuel pressure or clogged/sticking from varnish they will not mist the fuel properly and it will be to dense to efficiently make the proper air fuel mixture and burn properly. Easy check, are your plugs and pipes soot black?

[DESERTBEAR54]

Besides the injectors you should replace your main fuel filter that probably dried up in the last two months.

[hooligan]

If you stored the bike for the winter with gas in the tank, and didn't treat that gas with stabilizer and/or run all the fuel out of the injectors and fuel rail, there's a good chance that you have one or two partially fouled or sticking injectors.  The same principle would apply to carb bikes, btw.  Fuel sitting in the injectors, or jets in a carb, evaporates over time and leaves a varnish like material.  Easiest first action to take would be to pour some injector cleaner into the fuel (don't go nuts, use the amount specified per gallon on the container, not the entire can) and ride it at low speeds where it seems to run OK.  If it's a little varnish buildup, the concentrated cleaner should either clear it completely or at least clear it enough to verify that was the problem by the time you use up that tank of fuel.  If it helps but still doesn't completely correct the problem, it's fairly easy to remove the injectors and have them bench cleaned.  Even the typical Harley dealership should be able to handle it.

One reason it might run OK cold and progressively worse as it warms up could be that the injectors are sticking and leaking extra fuel into the intake.  Extra fuel is OK when the engine is cold, and in fact is required for starting and decent warmup.  Once the engine gets warmed up, however, excess fuel will make the engine blubber and run like crap.  If it runs way too rich, you may notice black smoke from the exhaust.


Jerry

I had the same problem with my Snowmobile ... Fuel evaporated and left a varnish like substance in the carbs .It ran fine when cold.Once it warmed up the varnish gets gooey and causes all sorts of issues with fuel delivery.

[SE-Mike]

grc
Bike only sat for a couple months and I get no black smoke out the exhaust. Plugs look great, even down at the bottom of the insulator.

hdbrad03
Under 10k

StrokedRider
I get no black smoke out the exhaust. Plugs look great, even down at the bottom of the insulator.

DESERTBEAR54
I don't see how it could get dried up if it was submerged in gas?

[lvse110se5]

What about a vacuum leak? I can't remember for sure, but I was thinking that the symptoms would be similar. Just a thought.

[jayray00SERG]

Ethanol wreaks havoc when sitting in a tank longer than a couple weeks. 10% being in just about all fuel, the volatile water  vapor eats fuel lines and clogs injectors. The rusting of a less than full untreated tank only adds to the problem. You don't want to know how I found out.

[DESERTBEAR54]

Mike I thought I read that you only had a gal of gas in the tank? Just sitting though and holding fuel they build up varnish and play havoc when you want to put the coal too it at higher RPMS. Don't ask me how I know that.

[HUBBARD]

Ethanol wreaks havoc when sitting in a tank longer than a couple weeks. 10% being in just about all fuel, the volatile water  vapor eats fuel lines and clogs injectors. The rusting of a less than full untreated tank only adds to the problem. You don't want to know how I found out.

Yeah, 'er 'uh, jayray,
 We called that chit "Moonshine" 'round here for the last 200 years.  I was readin' somewhere about makin' fuel out of sugar beets. Eco104, I think.  Later--HUBBARD 

[SE-Mike]

Had the bike in the shop and it turns out this problem was the check valve inside the fuel tank.

Problem fixed. 

[Hawg]

Had the bike in the shop and it turns out this problem was the check valve inside the fuel tank.

Problem fixed. 

good info  thanks