Hey guys, could use some help diagnosing.

2 nights ago the bike sputtered, gasped through the Air cleaner and died on the highway just cruising along at 60 mph in 6th gear. I had to turn off the kill switch and back on and then it started right up. This happened after 30 miles of riding. Then it got worse from there. Felt like fuel would cut out and surge. Random RPMs so not just off idle. Like you'd be pulling through 4th and right in the middle a big let off of power then back on in a half second, a stumble. I'd rap the throttle and could see fire shoot out the exhaust about 5 inches during the stumble part. Like it's trying to clear something out of it's system!

Then today after much research, I replaced the probably bad Crank Positioning Sensor. On my test ride it still happened after 15 miles of riding. That wasn't it I guess.

This time I saw a little oil on the rocker box cover of the front cylinder. I traced it to 2 of the bolt heads. Both felt a bit loose when I put the wrench to them. I did powdercoat the rocker covers two years ago, could they have come loose and caused this reaction?

The other variable is I filled up with gas the same day all this happened. Could it be a tank of bad gas? After half was gone I filled up again at a different station just to see, and put some HEET in to counter any possible water. Didn't fix it but then again I've still got some of that old tank of gas in there since I didn't completely drain it.

The tank was painted about 3 months ago...could there have been foreign particles clogging my fuel filter?

So, what I plan to do next is empty the tank, replace the fuel filter, pull the tank off to pull the rocker box covers, check the bolts and gaskets, then re-torque in sequence with a torque wrench. I did feel one of those rocker bolts give way and get easier when I reinstalled the cover 2 years ago after powdering them---it's one of the bolts that had oil on it and was loose. Maybe I stripped it back then. Would that really cause the bike to sputter and die though?

The bike did overheat on me last summer once, really bad with the engine light flashing and going solid. Could that heat have warped the rocker box cover? Would that cause these symptoms I wonder?

Not throwing any engine codes. All instruments and lights work when the bike dies on me so don't think it's electrical.

'07 SB with Thundermax ECM, Roland Sands Turbine A/C, and Bub dual exhaust. And I've been over the tuning multiple times and nothing out of whack. No loose wires or connections that I can see anywhere on the bike. Fuses are all good, and battery connections checked and clean/solid tight.

 

Couple ?? Did you wash the bike that day, do you have a pcIII.
The rocker box cover will not cause the bike tom run bad. Crank sensor should set a code.

 

My first guess would be bad gas, and just putting in a half tank of presumed good gas won't fix the problem. If there's something bad in the tank, and it's heavier than the gas itself, it's going to be at the bottom which is where the fuel pump is going to suck it up.

I think to be safe, I'd pull the tank and pull the fuel pump assembly out. Do a complete cleaning and inspection of the tank to ensure there is no water/foreign contaminants left in the tank. I can't remember if stock tanks are treated with a lining similar to KREEM, but you may want to check to see if you have any rust spots, etc...If you do, it's probably a good idea to get yourself a KREEM kit and treat your tank.

The rocker box cover won't cause the running problems you describe, but it should be fixed. You most likely do have a stripped receptacle, but I believe that can be fixed with a helicoil. At least it's worth a shot before you go out and buy a new head.

As for the overheating, it could have warped the rocker box cover since it was most likely loose at the time too. An easy way to check is to get a glass pane from a window that's big enough (glass is typically used because it is perfectly flat in order to avoid distorting the view through it) and put it on there. If it wobbles, it's warped. But warped doesn't mean unusable. If it's within a few thousandths of flat, proper torque and the gaskets would make up the difference.

 

No PCIII...I have a Thundermax ECM. Didn't wash the bike that day, but I did drive through a rainstorm about 8 days prior to this all starting.

Bad gas could be it...that wouldn't throw any codes? Should I use injector cleaner too? I doubt there is rust but I'll check. It's been garaged the entire time, 7000 miles on the bike, and only in the rain a few times.

I'll take care of the loose rocker cover, yes I think I'll have to helicoil it--my first time doing one! Also while diagnosing this problem I've been riding it pretty hard, and high RPMs sometimes, that could have led to the oil seeping out now and never before.

Here's to hoping it's just bad gas! Unfortunately I'm away from the bike for a couple weeks so I won't know for awhile.

On the crank sensor...all the symptoms of it failing exactly matched what I have. A large percentage didn't throw a code according to other posts and forums. When it did, it pointed to the CKP sensor and was solved when replaced. HD told me the crank sensor is on it's 4th revision for that part ("C" at the end of part number) so for $50 it was an inexpensive try I suppose.

If it's not bad gas or fuel filter clogged, I think I'm heading down the road of a possible Thundermax ECM problem, or injector wiring or ignition module? I would think a code would pop on most of those however. I wish the damn thing would just throw a code so I have a clue! May have to bring it to HD and have them conduct 1 hour of diagnosis, then fix myself. I just don't know.

 

Not sure on the thundermax but the pcIII connector to the ECM and pro gamer got wet and would cauSe all kinds of weird problems like you described

 

Here's my plan, chime in if you think order is wrong or I'm missing something.

1. Spray starter fluid between Roland Sands air cleaner and throttle body area to check for leaks.
2. Check exhaust header bolts for tightness and leaks
3. Empty tank completely and purge fuel lines
4. Remove fuel filter & check for clogs/debris, check internal fuel lines for pinholes, vent tube for clogs
5. Remove tank, rocker covers, clean bolts, re-torque usiug blue locktite (all to stop unrelated oil seepage)
6. Add fresh fuel, injector cleaner, and seafoam 1oz per 1 gallon
7. Check Tmax ECM connections and ensure they are all dry/clean
8. Back out wideband O2 sensors, then reapply anti-seize and put back in after cleaning tips

Check plugs/gap, check A/C for tightness.

If all that doesn't work, try to swap out the TMAX for the stock ECM for a test run.

IF didn't fix by now...take it in to the dealer and pay them to fix it or at least diagnose it so I can fix it.

Good plan??

 

When you take the TMax plug off the module, give it a coat of dielectric grease. But before you unplug it, remove the ECM fuse. And while you're at it, pull all the fuses, clean off any crud and put some of that grease on them.
Check all your battery cables, including the ground.

 

It sounds electrical, something shorting or rubbing? Would prob get a code if this was the case though. I had the same symptoms every time I put the brakes on, there was a short in brake light wiring.

 

I pulled all the fuses and didn't see anything that day...but I'll check again. I think I'll check fuel pressure...wonder if I can ride with a gauge on the line and see the drop or when it stumbles/hesitates?

 

Still having this problem. I pulled all fuses & applied dielectric grease and greased every connection under the seat, and on many sensors and plugs around the bike. Replaced fuel filter and cleaned inside tank and inlet sock. No pin holes in fuel lines inside the tank either. Pulled off intake, cleaned the butterfly valve and re-installed everything tight. Tightened a few rocker box bolts that were a little loose. Downloaded a fresh ECM basemap from Thundermax and applied it. Wiggled the injector wires looking for the infamous breaks and found nothing. Wiggle tested each wire I could find on the bike while idling and nothing induced the stumble/hesitation/dying. Checked O2 sensors close for loose nut or wire damage. Nothing. Added fresh fuel and Lucas fuel system cleaner (the guys have told me it's just as good as Seafoam?). I pulled the fuel cap off when it was surging, bucking, hesitating it and it didn't help so no vapor lock going on.

After all that it has gotten better. After 135 miles on this tank I've only had it die twice, and it just quit on me like I turned it off. Each time it wouldn't bump start...had to pull over and turn off/on RUN switch and then it fired up. Each time I could rap the throttle hard and hear some gurgle like it's a bit rich, with some back fire. Then it goes away for many miles. Before it would just get worse and worse and now it just goes away for a many miles.

Now the last 50 miles after sustained highway speed for 15-20 miles it will surge a bit, then start missing or hesitating, then will go away and pull strong for many miles after that.

I'm lost chasing this gremlin...still no engine codes! I wish something would just break already. Can't have it doing this on the way to Sturgis in a few weeks!