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Lack of Power

BUBBIE said:
....If you were to test the pressure of the fuel pump , that is all i can give you...We have had a rash of problems on some FI bikes with the tube in the tank rubbing a small hole in it and causing a Under Pressured fuel system...
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I could be wrong, but I think the black plug pretty much eliminates the fuel line/rail rub-hole. If it had a hole, it would be runnning way lean, resulting in clean to glazed plugs (both). Also, the ECM would have a hard time trying to make it idle. She has been stated to idle fine. Higher rpm flattening sure sounds like a coil to me. Since the coils have been checked out, I'm at a loss. I'd check them and their connecting circuitry again.

Good luck,
Rich P
 
Thanks RibEye,

The HD Tech said the coils were fine but I'm wondering if he tested them under load at high RPM. could they be malfunctioning at high load???

By the way....the fuel pressure is showing 3psi above required, so is fine according to same HD Tech.
 
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You mentioned troubleshooting and discovered that the front plug was "black and carboned" and the rear plug was clean. In my simple world that is where I would start with further investigating. Does the front exhaust pipe with the blackened plug get hot when you start it up? Have you tried a new plug in there? Have you traced the plug wires back to where they plug in? You said the bike was fine before the drive belt cratered. You did a compression check so the valves are holding. You replaced the injectors so that kind of eliminates fuel delivery. I am leaning toward something they did when they were tearing the bike down for a belt replacement. I am guessing you have a problem with a wire somewhere. I would be curious as to whether you have combustion in that front cylinder. This sounds like a simple problem but in the real world it can be very frustrating. The only thing to do is to start ruling things out, one by one until you finally step on it. Sometimes things like this can drive you to pull out the hard lemonade.
 
Several here have suggested it be electrical. They are probably close.... Did you say you replaced the spark plug and a new set of wires? or checked the spark wires? also are the coils Two separate ones? if so? reversing them to see if front cyl. runs clean and the back plug starts to be sooty?

Just a thought.... The others have mention on electrical...


On the coils - can check out like OK but still be bad under Load and Heat.
signed....BUBBIE
 
Retrop, yes the front cylinder does get hot on startup. She idles as normal and although accelleration not great up to 50mph, it doesn't struggle like it does after that. It never completely goes onto one cylinder as far as I can tell. Plugs have been replaced twice, recently for the screaming eagle set. Plug wires also checked using multimeter and seem fine and solidly connected.

Bubbie, I am leaning towards the coils at this stage and reversing them would indicate whether one was faulty under load. A mate of mine has suggested doing this also.

Although....The HD tech has stated that since I have a Terminal Velocity 3 module to cope with the S&S cams that the ECM could be going into "Limp home mode" all the time but all the sensors are coming up "OK" and I did a 10,000 mile road trip to Alaska last summer without a glitch...?
 
Not that I know anything, but, I have heard that if the crank sensor goes out, the ECM will derive timing from the other sensors, and limp well enough to run. It is possible that at idle rpm, the derived "limp" timing could be more accurate than higher rpm. However, 50mph is not exactly higher rpm, just higher speed. Also, limping should, in my mind anyway, manifest pretty much equally in both jugs, and the single sooty one is working against that analysis.

I'm just thinking out loud here...

Enjoy,
Rich P
 
I don't know much myself hence on here. I seem to remember reading somewhere that the rear cylinder fuel supply is trimmed back based on the fuel going to the front. Is this correct? and if it is and we assume we are in "Limp" mode would that account for the sooty front and not the same effect in the rear.

just to recap, I know I said idle is smooth but acceleration is not exactly what you would expect even up to 50mph. This was very obvious recently when I could not keep up with the sportster 883 accelerating in front of me, embarrassing???
Over 50mph a throaty sound seems to be coming from the lower left side when you twist the throttle and she is struggling.
 
Willie,may sound crazy but hows the air cleaner look, also what kind of pipes r u running [clogged baffles, etc.] speicaily after injecters where replaced, good luck, sorry about the spelling to early.
 
Boy you have gotten some great advise, and it seems that most think it is some type of electrical problem and it might be. I don't want to sound to dumb here but it was after the belt was replaced. Have you raised the rear wheel up to see how freely it spins? It seems to me if there is enough resistance it can cause the engine to lug down and for the throttle response to be less than what you are used to. It's just a wild guess but if the wheel is misaligned or belt tension to tight might be enough to cause a problem.
 
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