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Engine skip or "Bucks"

Lobo1

Lobo1

Junior Member
Hopefully I am in the correct forum with this thread. If no maybe one of the moderators can move it to the correct one.
My 05 FLHTCI just started acting weird this past Wednesday night on my way home. It began an occasional "skip" or maybe a better way to describe it would be a "Buck" when the RPM's were around 3000. At first it would only do it once but it got progressively worse to the point I was beginning to wonder if it was going to make it home. At faster speeds and higher RPM's it doesn't do it. In 4th gear around 37-40 mph or in 5th at around 50-55 it does it. It also began being a little stubborn about firing up when I shut it off for 2 - 3 minutes with the engine at operating
temp. It wants to spin over several times and then spit back through the intake / breather. I thought maybe the crankshaft position sensor might be the culprit. But I just had a cam tensioner job done two weeks ago. Upgraded to hydraulic tensioners with new oil pump, guides, cam support plate. Also had front head replaced due to broken exhaust stud which I inherited from previous owner. I burn Shell 93 octane gas. 46,144 miles on the clock. Any suggestions greatly appreciated.
 
Have you checked for codes? It could be your CPS, although strange at certain rpms and not more consistent. I wouldn't think your cam chest work would have anything to do with it either. Possible intake leak?
tourbox
 
I checked for an intake vacuum leak just a few minutes ago. Didn't see and difference in RPM's. I'm getting it scanned later today. Buddy of mine has a scan tool for Harley's st his shop. He thinks it's the tubing in the fuel tank or possibly the tuner out of whack since the hydraulic upgrade is so much more precise in keeping the timing in tact. ?????
 
Remove the gas cap and turn on the ignition, listen for the pump to energize. If you get the 3 second or so buz that's normal, listen for a swishing or spraying sound. If you have that sound you most likely have a pin hole in the fuel tube.

As tourbox said, check for codes, that could tell you a lot about what's going on.
 
I will check the fuel line in the tank for pressure bleeding off when I get back home. I will also update the findings when I get the codes scanned today. ( if it doesn't start raining again) otherwise it will be tomorrow.
 
I would also check on the forum for info about cleaning the IAC. The symptoms you described are sometimes characteristic of a gummed up IAC.

Cleaning the IAC is not too difficult, but in my experience does not last very long as a solution. I was cleaning the IAC on my '03 every few months. So I finally bit the bullet and replaced it. Not difficult or expensive to do. But I do not think you need to follow the Service Manual on this replacement. I did NOT remove the throttle body assembly when I did it. Just raised up the tank a bit so I could get hands and tools in to take it out and install the new one. Did remove the A/C backing plate I think, just to have a better view and easier access.

Cheers,

TQ
 
I will check the IAC this weekend. I called the dealership after reading your comment and they have it in stock.
BTW, my buddy checked fuel pressure with his gauge and it was fine. We checked for codes both with on board diagnostics and his scanner. No codes. I told him to get on it and ride it while keeping the RPM around the 2000 range. (I think I said 3000 in an earlier post but that is a result if my big ole finger hitting the 3 instead of the 2. He got back about 20 minutes later. Said it did it once and no more. I rode home and tried every way in the world to make it do it. Never did.
I am still going to check the IAC along with checking for an electrical short. I know it will come back sooner or later.

I just bought this scooter a couple months ago. I had a 1988 FLHS Electra Glide sport I bought new. Gave that to my son when I bought this one. First twin cam I ever owned. I had 7 other Scooters during the 29 years I had the FLHS. Always had Evo's and a couple shovels. Still trying to get edjumacated on Twin Cams.
 
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To follow up on TQ's post the best way to avoid the IAC from gumming up with the oily junk is to vent to the atmosphere.
The procedure can be found in the self help section of the forum. It's pretty straight forward and takes about 15 minutes to do.
 
I'll look it up in the self help forum. This weekend I will jump into it. Thanks
 
I'm wondering if maybe the ignition coil may be showing early signs of failure? With 40,000+ miles on her, sounds like all is ok at cold start-up and begins to "buck" when warmed up to operating temps, it's a possibility, eh?
 
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