My first post here, although I've been reading up some. I'm working on a Friend's F.I. 2005 California Platinum.
The problem is this:
It sat for a several months, wouldn't run off an idle. Grab a fist of throttle, and it coughs, spits back, hesitates, and dies unless you let off.
Pulled the tank and someone had removed the filter that comes unhooked, and bypassed it. So I left it that way.
I started checking stuff out, eventually remounted the tank, started it up, and voila, after tweaking the position of the TPS slightly, it started running just fine. Now, I moved the TPS like an old fashioned mixture adjustment, just slightly moved it till the idle smoothed out and it then responded smoothly to throttle.
Fine. Done.
Couple of weeks later, my friend tries starting it again, the problem's back.
Did some reading on the web, sounds like the TPS. Pick up a TPS at a swap meet, it's a harley part, but it's a PF1C, not the PF3, or 4.
Well, didn't solve the problem, put the original PF3C back on, get out the oscilloscope and look at the waveform off the variable output of the TPS. It presents a smooth flat DC waveform that changes with the throttle position and appears to be doing just what a fancy potentiometer should do.
H'mmm. Next look at the wave form on the fuel injectors.
It's a negative going pulse, from 12v to approx 0v, that varies from about 5millisec to 15 millisec when I grab a fistful of throttle. The engine, however, when I grab that fistful, coughs, backfires, hesitates and otherwise does not want to rev up.
So, the question is, does it seem reasonable to assume that perhaps it isn't an electronic issue, but a fuel delivery issue, as in not enough?
Obviously, I don't have access to the fancy software diagnostic tools.
Also, when I had the tank off, I checked the pressure fuel pump press. by jerry rigging it up to run and putting a press. gauge on the output. looked o.k, ideas?
Thanks,Dick
The problem is this:
It sat for a several months, wouldn't run off an idle. Grab a fist of throttle, and it coughs, spits back, hesitates, and dies unless you let off.
Pulled the tank and someone had removed the filter that comes unhooked, and bypassed it. So I left it that way.
I started checking stuff out, eventually remounted the tank, started it up, and voila, after tweaking the position of the TPS slightly, it started running just fine. Now, I moved the TPS like an old fashioned mixture adjustment, just slightly moved it till the idle smoothed out and it then responded smoothly to throttle.
Fine. Done.
Couple of weeks later, my friend tries starting it again, the problem's back.
Did some reading on the web, sounds like the TPS. Pick up a TPS at a swap meet, it's a harley part, but it's a PF1C, not the PF3, or 4.
Well, didn't solve the problem, put the original PF3C back on, get out the oscilloscope and look at the waveform off the variable output of the TPS. It presents a smooth flat DC waveform that changes with the throttle position and appears to be doing just what a fancy potentiometer should do.
H'mmm. Next look at the wave form on the fuel injectors.
It's a negative going pulse, from 12v to approx 0v, that varies from about 5millisec to 15 millisec when I grab a fistful of throttle. The engine, however, when I grab that fistful, coughs, backfires, hesitates and otherwise does not want to rev up.
So, the question is, does it seem reasonable to assume that perhaps it isn't an electronic issue, but a fuel delivery issue, as in not enough?
Obviously, I don't have access to the fancy software diagnostic tools.
Also, when I had the tank off, I checked the pressure fuel pump press. by jerry rigging it up to run and putting a press. gauge on the output. looked o.k, ideas?
Thanks,Dick