Softail Models Standard, Custom, Night Train, Deuce, Springer, Heritage, Fatboy, Deluxe, Rocker and Cross Bones.
Sponsored by:
Sponsored by:

Engine hesitation when accelerating

Thread Tools
 
Search this Thread
 
Old Sep 20, 2018 | 06:57 AM
  #1  
JM Rossi's Avatar
JM Rossi
Thread Starter
|
3rd Gear
Joined: Sep 2018
Posts: 7
Likes: 0
From: Solon, OH
Default Engine hesitation when accelerating

I have a 2003 FLSTC that is backfiring and hesitating when I accelerate. The more throttle I give it, the more it jerks. Eventually, it "kicks in" and goes. It cruises smoothly at speed or if I accelerate slowly. I have tried fuel injector cleaner, but it didn't help.
 
Reply
Old Sep 20, 2018 | 06:59 AM
  #2  
Notgrownup's Avatar
Notgrownup
Seasoned HDF Member
15 Year Member
Loved
Top Answer: 1
Top Answer: 3
Joined: Mar 2009
Posts: 24,765
Likes: 9,320
From: Snow Hill, NC
Default

Fuel filter dirty maybe, sometimes 1 injector treatment isn’t enoug, remember, it didn’t get clogged overnight...
 
Reply
Old Sep 20, 2018 | 07:11 AM
  #3  
JM Rossi's Avatar
JM Rossi
Thread Starter
|
3rd Gear
Joined: Sep 2018
Posts: 7
Likes: 0
From: Solon, OH
Default

Thank you for your quick response. Is the fuel filter hard to change?
 
Reply
Old Sep 20, 2018 | 07:34 AM
  #4  
JM Rossi's Avatar
JM Rossi
Thread Starter
|
3rd Gear
Joined: Sep 2018
Posts: 7
Likes: 0
From: Solon, OH
Default

There is no mention of a fuel filter in my service manual.
 
Reply
Old Sep 20, 2018 | 09:23 AM
  #5  
Notgrownup's Avatar
Notgrownup
Seasoned HDF Member
15 Year Member
Loved
Top Answer: 1
Top Answer: 3
Joined: Mar 2009
Posts: 24,765
Likes: 9,320
From: Snow Hill, NC
Default

It's at the petcock... see attached link #27

http://partsfinder.onlinemicrofiche....=44&c=0&d=2003 FLSTC SOFTAIL® HERITAGE CLASSIC (CARB) (BJ) FUEL TANK SENDING UNIT ASSEMBLY
 
Reply
Old Sep 20, 2018 | 03:21 PM
  #6  
Pitbull_Dallas's Avatar
Pitbull_Dallas
Road Master
Joined: Nov 2013
Posts: 852
Likes: 54
From: Dallas tx
Default

Sounds a bit like the fuel pressure regulator housing in the tank has pushed off and you're losing fuel pressure. What you described sounds very much like what my bike did when the housing pushed off. They are notorious for that..

If you don't want to pull the fuel pump assembly out of the tank yourself, just ride it up to a dealer and have them check the fuel pressure. Just takes a minute.

I had a thread going on that problem a while back. Search it out and have a look.
 

Last edited by Pitbull_Dallas; Sep 20, 2018 at 03:28 PM.
Reply
Old Sep 20, 2018 | 03:33 PM
  #7  
Jackie Paper's Avatar
Jackie Paper
Seasoned HDF Member
15 Year Member
Community Builder
Liked
Top Answer: 1
Joined: Mar 2010
Posts: 38,728
Likes: 6,491
From: Honah Lee
Default

You say fuel injector cleaner. I sort of think you have fuel injection? But letters would be FLSTCI. If you do, the filter is in the tank from the top. If it is carb. Check screen at petcock. But first, remove the air filter and make sure you see a shot of gas looking back thru carb when you twist throttle wide open. A stumble is usually associated with accelerator pump for that extra fuel needed for that sudden increase with air from a rapidly opening throttle.

A stopped up filter on a carb bike will limit top speed or even the power to go up a hill. On a fuel injected bike, it will kill idle first long before it gets so bad to affect top end.

A cleaner is a waste in my opinion. If you dump it in a FI bike tank, if it does anything, all it does is screw up the tank, cause rust and then that dumps into the actual fuel filter and worst into the small screens in the top of the injectors.
On a carb bike, it rarely can open jets and just spraying in the opening of intake kills sensors by washing dissolved black crud up past o-rings and drying crud up in them.
 

Last edited by Jackie Paper; Sep 20, 2018 at 03:48 PM.
Reply
Old Sep 20, 2018 | 08:27 PM
  #8  
Burbur2's Avatar
Burbur2
Grand HDF Member
5 Year Member
Liked
Loved
Community Favorite
Joined: Aug 2017
Posts: 3,589
Likes: 891
From: Nowhere
Default

Had same exact issue in the past took me a year to figure out. Turned out spark plugs wires were faulty 20$ fix.
 
Reply
HD Forum Stories

The Best of Harley-Davidson for Lifelong Riders

story-0

10 Most Awkward-Looking Motorcycles Ever Built

 Verdad Gallardo
story-1

Jason Momoa Is Turning Classic Harleys Into PHEVs

 Verdad Gallardo
story-2

Harley-Davidson Fat Boy Becomes a Dark, Decepticon-Inspired Custom

 Verdad Gallardo
story-3

6 Weirdest Harley-Davidsons Ever Sold to the Public

 Verdad Gallardo
story-4

7 Times Harley-Davidson Chucked Tradition Out the Window

 Verdad Gallardo
story-5

7 Surprising Harley-Davidson Products that Are Not Motorcycles

 Verdad Gallardo
story-6

8 Best Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-7

10 Worst Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-8

Killer Custom's Jail Break Is The Breakout That Refused to Blend In

 Verdad Gallardo
story-9

Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

 Verdad Gallardo
Old Sep 23, 2018 | 08:06 AM
  #9  
JM Rossi's Avatar
JM Rossi
Thread Starter
|
3rd Gear
Joined: Sep 2018
Posts: 7
Likes: 0
From: Solon, OH
Default

Sorry for the delay in responding to you. I made an appointment to have the pressure checked. One more thing though, it seems the problem is intermittent. I took the bike out a couple days ago and it ran like a top. I could not get it to hesitate at all. Great power and acceleration. Then yesterday the problem returned..
 
Reply
Old Sep 23, 2018 | 08:09 AM
  #10  
JM Rossi's Avatar
JM Rossi
Thread Starter
|
3rd Gear
Joined: Sep 2018
Posts: 7
Likes: 0
From: Solon, OH
Default

My bike is fuel injected so I guess its code is flstci. Thank you for the tip regarding fuel injector cleaner.
 
Reply



All times are GMT -5. The time now is 08:00 AM.

story-0
10 Most Awkward-Looking Motorcycles Ever Built

Slideshow: Not every motorcycle can be a design icon, and these machines prove that bold styling doesn't always age gracefully.

By Verdad Gallardo | 2026-06-12 11:58:41


VIEW MORE
story-1
Jason Momoa Is Turning Classic Harleys Into PHEVs

Slideshow: Jason Momoa's latest restoration project blends 1920s Harley-Davidsons with modern electric technology, creating some of the most unusual hybrid motorcycles ever built.

By Verdad Gallardo | 2026-06-10 17:18:58


VIEW MORE
story-2
Harley-Davidson Fat Boy Becomes a Dark, Decepticon-Inspired Custom

Slideshow: Killer Custom's latest build relies on styling changes rather than performance upgrades, giving the cruiser an entirely different personality.

By Verdad Gallardo | 2026-06-03 18:28:05


VIEW MORE
story-3
6 Weirdest Harley-Davidsons Ever Sold to the Public

Slideshow: From military-inspired singles to scooters and three-wheel utility vehicles, these Harleys took the company far outside its comfort zone.

By Verdad Gallardo | 2026-06-02 18:34:10


VIEW MORE
story-4
7 Times Harley-Davidson Chucked Tradition Out the Window

Slideshow: Harley-Davidson built its reputation on nostalgia, but every so often, the company took a hard left turn into the future.

By Verdad Gallardo | 2026-05-20 11:18:19


VIEW MORE
story-5
7 Surprising Harley-Davidson Products that Are Not Motorcycles

Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.

By Verdad Gallardo | 2026-04-29 16:50:35


VIEW MORE
story-6
8 Best Harley-Davidson Motorcycles Ever

Slideshow: Not every Harley gets it right, but these are the ones that genuinely earned their reputation.

By Pouria Savadkouei | 2026-04-15 14:23:21


VIEW MORE
story-7
10 Worst Harley-Davidson Motorcycles Ever

Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.

By Pouria Savadkouei | 2026-04-01 20:01:09


VIEW MORE
story-8
Killer Custom's Jail Break Is The Breakout That Refused to Blend In

Slideshow: Killer Custom's "Jail Breaker" build focuses more on stance and visual aggression than mechanical overhaul.

By Verdad Gallardo | 2026-03-18 19:20:32


VIEW MORE
story-9
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.

By Verdad Gallardo | 2026-03-07 16:15:30


VIEW MORE