2012 120R LOADS UP (no spark)

[fbn ent]

Friend's '12 FLT with a 120R will start on the first spin initially then (doesn't matter if it's a minute or an hour riding) will either crank through a few revolutions and start or will have no spark (it seems) and after a few attempts will back fire or make that hollow/flooded sound in the exhaust and lite up. This has been going on for a while and is getting to the point he can't trust it. It is getting fuel and runs like, well, a 120R hotrod otherwise.

It shows no codes. I figure it is losing spark somehow (CPS?) and told him to pull it and we will try my known good one. Any other K.I.S.S. ideas?

[fbn ent]

No CRs.

[1workinman]

Will the key fob keep it from starting if battery dies .

[fbn ent]

Yep..new batteries. It starts fine when it starts...

[Scotty]

So you tried a known good crank sensor (CKP) and that did not change anything is that right?  CPS stands for cam position sensor which they haven't used since 2001.
CRS = can't remember "Potty mouth" 

[Durwood]

How old is the battery in the bike?

My old Twin Cam Road glide would do the same thing when the battery was getting weak.

Fire right up when cold, ride it to get gas, shut it off, then on restart it would roll over a couple of times and backfire before finally starting.

[fbn ent]

So you tried a known good crank sensor (CKP) and that did not change anything is that right?  CPS stands for cam position sensor which they haven't used since 2001.
CRS = can't remember "Potty mouth" 

...............yeah, I suffer from CRS for sure. Yes, I was referring to the CranKshaft Position sensor.....

And he hasn't pulled it yet to try mine. Plug is under all kind of stuff up front and he's hoping for it to heal I guess.

Durwood....don't know about the battery, guess it could be an issue. I'll check the drop today.

[fbn ent]

Battery is new, just spent some time with him trying the known good CKS. No change. Running a HD tuner.

Again,
*  It starts and idles fine at first.
*  On restart, after cycling the ignition, it will start after cranking a little longer than the first start.
*  On second restart, again after cycling the ignition, it will crank maybe four or five revolutions before firing.
*  On third restart, yes after cycling the ignition, it will not fire.
*  Fourth attempt will give a burp out of the pipes.
*  Fifth attempt will give a backfire from the pipes and it will start.

Mostly the same pattern whether it is a short duration or an hour riding....

Runs strong when it runs. He is going to have to take it back to the shop that did the work (3 hours away) if we can't figure it out.

It is so predictable it's driving us nuts ! 

[chaos901]

Sounds like something electrical is getting warm/hot and not working any longer.  I can't recall enough to properly suggest where to start looking though.

[fbn ent]

Yeah, that's what I was thinking but to run great any other time than this start thing baffles me.

Swapped the system relay with the brake relay...nope.

[chaos901]

So, is there anything that is different in the starting sequence checks and balances that is not present during a normal running sequence?   Again, not something I know off hand. 

[fbn ent]

Don't know, I'm hoping someone can shine some  on it. You are right though, it's like something is missing in the sequence.

[Scotty]

So many things it could be.........a sensor, throttle body (plate or shaft), ECM, wiring, coil, plugs, plug wires and the tune
It could be a number of things but who did the tune and do they have to much fuel going in on a warm startup that is fouling the plug as a backfire in the pipe tells me raw fuel is igniting in the pipe. That is where I would start now that the crank sensor is tested fine.

[fbn ent]

They tuned it, they can figure it out.....I don't have the time to spend on it....he's going to have to take it back in to the shop. I don't have the software for it to even try...

[Hossamania]

Temp sensor is all I've got to contribute.

[Ohio HD]

Didn't the 2012 originally have ACR's? Are they just not being used?

If they're just unhooked, or the heads being used don't have provision for them, could this be effecting the ECM after initial start?

[Coyote]

Didn't the 2012 originally have ACR's? Are they just not being used?

If they're just unhooked, or the heads being used don't have provision for them, could this be effecting the ECM after initial start?

The ECM will throw an error code if they are enabled but not installed.

[Ohio HD]

Didn't the 2012 originally have ACR's? Are they just not being used?

If they're just unhooked, or the heads being used don't have provision for them, could this be effecting the ECM after initial start?

The ECM will throw an error code if they are enabled but not installed.

Could be, but wondering why there are no CR's?

No CRs.

[fbn ent]

He said he was told they weren't recommended for the S&S heads he put on it...

[Ohio HD]

OEM ACR's won't bolt onto S&S heads, but they could have been made to fit by a competent cylinder head shop. Head type really has no bearing on effectiveness of compression releases. If he has any compression to speak of, I'm surprised it cranks over hot.   

[FSG]

a 120 with no CRs ........  what Cams  ?


pull the front plug out once is't been run and hot, will it crank and start on the rear cylinder ?

[fbn ent]

I told him to try that but he didn't make it happen. Maybe tomorrow....

It cranks fine and should fire but when it is in the "no fire" state it's like the spark has been turned off. I'm going to try and check the spark when warm and acting up just to see if for some reason there is none. The plugs aren't all sooted up from restarting it so many times so I kind of don't think that it is over fuelling.

Don't know what cams but I'll ask him. Goes like the proverbial bat though!

[fbn ent]

He says "Easy Start" cams.....I can get the build from him if it makes any difference.

He's gone riding, see if he gets back. LOL!

[Scotty]

S&S easy start cams and adjustable pushrods set to deep into the lifters if they bleed down to much will cause those problems as will to much startup fuel as I mentioned before.
If he has adjustable pushrods tall him not to go past 3 turns deep.

[fbn ent]

Scotty....Thanks for that. This issue started last year after the build but wasn't as bad as now. He wasn't able to ride it much since he was incarcerated....would the lifter issue get worse as the top end breaks in?