Hesitation Solved! Maybe someone can take away something from my experience

Started by Tacocaster, May 11, 2019, 02:37:07 PM

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Tacocaster

2007 Street Glide - original owner, HD 103 Kit, S&S EZ-Start 551 Cams, Big Boys ported heads/Dyno tuned, V&H True Duals w/Monster Ovals and over 120K miles (and gremlin bell).

It's been two years since the first time she hiccupped on me (suspected bad gas – always burn 90+ Octane) running w/Cruise on at 75 mph. Re-occurred only two or three more times that year - always on cruise and never reflected in the tach needle dropping-out. Also no codes whatsoever - ever!

The next year (2018) the hesitation started to become more frequent, yet still intermittent and now frustrating! Occurring at cruise and ONLY when hot (operating oil temp. showing min. 190 deg F) simple light increase rpm on the throttle clears the hesitation immediately every time - yet never a start-up, idle, roll-away or hard sustained roll-on throttle problem with engine hot or cold. WTF?

First observation was the throttle body intake tract very "sooty" with the air cleaner off for cleaning. So, removed the TB and Intake to clean the fuel tract (twice), fuel injectors, TPS, MAP, IAC and K&N Filter.
How did this happen? During a senior moment I had over-lubed the air filter and gummed-up the intake tract pretty good. I replaced the manifold intake seals and made a mental note not to do THAT again!
Follow-up test ride showed no change.

To next approach the problem I installed a known good spare coil, new plugs and known good spare plug wires because I had them (even though the tach never showed deflection) but the hesitation continued and was again increasing in occurrence. I stopped riding with my possie to avoid ruining a good ride with a complete breakdown.

Now using the factory electrical diagnostics and service manuals, I began bench testing the Fuel Injectors for flow and pattern, the Engine Temp Sensor for steady output over an increasing heat range and the Throttle Pos. Sensor for smooth transition while slowly increasing/decreasing the throttle grip, the O2 sensors - and of course the tried and true "wiggle test" (built an ECM breakout box by re-purposing the cables from an old PC-V module). Nothing stood-out.

Justified by over 120K miles on the clock I next began systematically replacing then test riding each of the fuel-related EFI sensors and both O2 sensors one at a time thinking maybe my bench testing was flawed - all to no avail. Now very perplexed and too cold to ride, I put her to bed for the winter.

This year I replaced the fuel filter (just over 50K miles) then battery (7 yrs old tested weak on Load test) and gas cap (borrowed a buddy's). No joy!

Finally the fuel pressure regulator (over 120K miles) was replaced.  Today was the first time in two years it ran without a glitch.

Am I happy? Betchurass!

What did I learn? With EFI bikes, you need the proper test tools - or in their place, patience, persistence and luck. Deep pockets are a necessity either way but I justified the expenditure for the new parts over the tools this time with, "she's a keeper so the aged components replaced now become 'known good' if I ever need to troubleshoot again." Well, that's my logic....flawed or otherwise.

With my home-built ECM Breakout box I'm now tracking Fuel Pressure Testers online (HD compatible testers range from $110 - $900 USD). Gotta build-up the EFI Tool box!

Hope there might be something in this experience that might help someone else.

Tacocaster
We're all A-holes. It's to what degree that makes us different.

Pirsch Fire Wagon

Fuel Pressure Test would have showed that immediately when the ignition was turned off (fast bleed down every time) . You can build one for about $40 I'll see if I can find the link for parts and post it.
Tom

pauly

I believe an even rude outboard fuel fitting will fit the tank fitting - then get a cheap pressure gauge and job done.
Thanks
Pauly