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'03 FLHTCUI running lean

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coop85

Member
I have been chasing a issue with my bike for months with no luck so far. It was running great for 30,000 then suddenly started to miss with it popping through the intake. All the 'experts' say it's running lean, as to the problem nobody is in agreement. I've replaced nearly all the sensors in the engine as well as the throttle body. I did some testing and discovered it runs great for about 34 seconds after starting. Doesn't matter how long it ignition switch has been on, but timing after the actual start is significant. Also doesn't matter if the bike is cold or hot. I can be on the highway, wait for it to sputter, turn it completely off while coasting, wait a few seconds, turn it back on and it will run great for 34-45 seconds and then start to miss.

My question is, is there a particular event in the ECM that causes the bike to run a predetermined fuel setting without looking at any sensors for around 30 seconds, or any sensor this would lean to? Again, I've replaced all the sensors except the crank position sensor as well as wiring from the terminal back about 12" to all sensors and replaced the pigtails to the fuel injectors.

BTW, the bike misses the same on each cylinder with the other plug disconnected.

Thanks!
 
Two things come to mind, they are an intake leak or a cylinder head temp sensor.

Might be helpful if you tell us the sensors that were replaced.

Have you tried spraying around the intake module also with some carb cleaner to see if it stumbles.
 
Thanks, yep I should have provided ,more info.

It has the following work done already:
new plugs and wires
map sensor
engine temo sensor
intake seals
throttle body
fuel filter
wiring to MAP, TPS, eng tem sensor, fuel injectors

After I replaced the throttle body I now get a check engine light. Using the engine light diagnostics I may be getting a code11. After the light comes on after the 4" on 6" off cycle it stays on for about 10" then a very momentary flash then back on indefinitely. Not really sure if that's a 11 or not. If so one sheet I have says open system relay contacts, another says TPS open or closed.

Thanks
 
coop85 said:
Thanks, yep I should have provided ,more info.

It has the following work done already:
new plugs and wires
map sensor
engine temo sensor
intake seals
throttle body
fuel filter
wiring to MAP, TPS, eng tem sensor, fuel injectors

After I replaced the throttle body I now get a check engine light. Using the engine light diagnostics I may be getting a code11. After the light comes on after the 4" on 6" off cycle it stays on for about 10" then a very momentary flash then back on indefinitely. Not really sure if that's a 11 or not. If so one sheet I have says open system relay contacts, another says TPS open or closed.

Thanks
Click to expand...

Harley Davidson Community self help section:s
 
Thanks, that was one of the sheets I referenced. However, the light only came on after I replaced the throttle body so it was probably me although I can't imagine how. The symptoms remain the same either way.
 
coop85 said:
popping through the intake.
Click to expand...

Popping through the carb, sounds like scattered spark timing or extra spark events. I would take a close look at ignition triggering.
Is your 2003 single fire or dual fire ignition..

When you replaced the throttle body did you measure the TPS voltage when at zero throttle. That can be off if you transferred your TPS to the new throttle body.
 
"When you replaced the fuel filter, did you inspect/pressure check the conveluted plastic fuel line inside the tank for pin holes?"

No, but the fuel pressure check came in at 38 psi. Should be 58 so there may be an issue, however I was told that was plenty of pressure to run the bike at idle power. There is also no sound of a leak after the fuel system pressurizes. Also, at least in my mind it wouldn't make sense for the leak to not be a factor for 30" after starting.

Also, I fixed the check engine light...installation error on the TPS.

"Is your 2003 single fire or dual fire ignition."

The ignition is stock so I presume dual fire ignition.
 
coop85 said:
No, but the fuel pressure check came in at 38 psi. Should be 58 so there may be an issue, however I was told that was plenty of pressure to run the bike at idle power.
Click to expand...


38 lbs will just run at idle but will not be enough to run at any more than idle on a good day.


Have you checked the filter ? You may have a bad pump too.
 
glider said:
Have you checked the filter ? You may have a bad pump too.
Click to expand...

I replaced the filter and wouldn't be surprised if I managed to cause the low fuel pressure by not getting the clamps quite right. However, swapping out the filter had no effect on the way it runs. It misses at idle and will eventually quit. The bike accelerates pretty well up to highway speeds, although not quite as well as it used to.
 
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