'07 FXDB Sometimes Won't Start When Hot.

[Tom H]

2007 Street Bob 96" Dyna 18,000 miles. Only mods that I know of are the handlebars, seat and saddlebags.

Issue is that when ridden on the freeway at about 65-70 for lets say 1/2 hour more or less and "normally" in hot weather (happened today with about 65 deg F) and then stop at a store for a few minutes, it will crank fine until you wear the battery down, but not start. This is at least the second time it has done this. To get it to start, a jump pack was needed. First time AAA and it started right up., This time a small bike portable jump pack. But, it still did not start right up, cranked faster though. Seems like I had to let it cool down 15 or more minutes before it would start.

I did check for spark by pulling the plug wire using a screwdriver into the boot and holding it next to the head. It did have spark.

One thing I have noticed when it wont start is the small of "nasty" burnt fuel. Sorta like it's rich. This bike is FI. The second thing I noticed today was with the stock air cleaner off, it would occasionally belch a bit of fire from the TB while cranking it with the butterfly about 1/4 open.

I did finally get it to start with the air cleaner off. Seemed to help if I held the throttle open a bit.

Once I got home and shut it off, tried to start it and it would crank, but again not start. Moved on to other things and then about 1/2 to an hour latter I tried to start it and it cranked and started up 3 times in a row perfectly just like it should.

The issue does not happen all the time, just once in a while. When it did this today, I got off the freeway and stopped for a few minutes. fired up normally. Stopped a few miles latter for about 10 minutes and that was when it would not run.

Any thoughts?

Thank you!
Tom

[FXDBI]

Heads venting into the TB? If so I would start with cleaning the TB with brake cleaner and wipe it clean. I would also pull the crank sensor and make sure there is nothing on it. Try those 2 things and see if it improves.   Bob

[Tom H]

TB looks very clean.

I'm thinking maybe the crank sensor as you mentioned. But I thought they work or they don't. Could heat effect it?

This issue is a hard one to replicate. Only does this once in a while.

Thank you!
Tom

[kd]

The easy test is the fuel cap / vent. The heat of the engine under the tank could be raising the fuel temperature and causing enough expansion to pressurize the fuel line if it isn't venting.  A dribble at an injector may be causing a flooded condition. 

Next time or any time you get it hot loosen the fuel cap off as soon as you shut it off to ensure the tank is venting.  When you return try to start it before retightening the cap.  If the no start problem goes away you probably have a venting problem with the cap.  If the problem persists you can probably assume the tank vent is OK.  If not the cap or an injector are suspect.


How good is the battery?  A battery that loses it's punch (even though it still cranks) may not be ticking it over fast enough for that instant fire-up.  The fact that a jump has resolved it previously may be indicating this unless it just sat long enough.  Check the voltage at the battery while cranking and expect to see around 10 volts minimum. Hot starts can be harder cranking and draw more from the battery when cranking. Letting it cool for a bit can alleviate the draw enough to get it to fire off on the first flip or two.

The engine temperature sensor can effect starting too.  It usually will warn you of a problem by running rich when it gets hot.  Often it will be bad enough to cause backfiring in the exhaust and intake like you describe.  The problem with diagnosing the ETS is it doesn't throw a code.  If all other tests and checks are good changing the ETS is an option.  They are not too expensive so if it doesn't work you will have a spare.  It is a fairly common failure so you may be glad you have a spare.

[Tom H]

I just pulled the crank sensor, no debris, just some oil on it. I guess to make sure it's not a corroded connection, I have to pull the regulator to access the connectors?

This last time it had the issue. I pulled the gas cap just to make sure that was not the issue.

As I mentioned the issue seems to come up after a freeway run but not often enough to test it. Freeway run, less than 5 minute stop (started perfect and ran perfect), another stop of about 10-15 minutes and the no start issue for at least the second time that I can remember. Once started it ran normal. Got home, shut off, tried to restart, it started, shut off, tried again and back to no start.

While I was cranking it, maybe twice it sounded like it was trying to start, but running on 1 cyl. and badly at that and needed to keep cranking the starter to keep it barely running.

The bike does not have a backfire issue from the exhaust. I believe it's the factory exhaust. The fire out the TB was when it was having it's issue ( I had the air cleaner off to see if I could see it flood) and I held the butterfly open a bit. Only saw the flame, but no backfire.

When the bike is hot, I do not smell a rich exhaust. But, again as mentioned, with the issue, the exhaust is the nastiest smelling and like it's rich.

Battery is about 3 months old has been reliable, better than my M Bat one. I had this issue the previous time with the M Bat and thought that it may have been the battery failing and bought a new battery, thundercrank I think. Been fine until now. Even sat for a few weeks and fired right up, the M Bat didn't seem to do that very well.

I'm pretty sure it's a heat issue. Just what component is it effecting is the question?

Thank you so far!!!
Tom

[kd]

Have you had the fuel line from the tank to the Injector connector off at the tank end?  It can be a problem if not reassembled carefully.   

[Tom H]

I have pulled the tank before, I think twice. But that was a few years ago. Been fine until about 6-8 months ago when "I think" it did this issue the first time.

Changed battery, thought I had it fixed. I only carried a small jump box so that in case it happened again, I wouldn't have to wait for AAA. When they jumped it, it started right up. But...then again, it had cooled for about 1/2 hour before AAA showed up.

Thank you!!
Tom

[FXDBI]

TB looks clean you say, but are the vents fed into the TB?  If so maybe when you get it hot the vents leak and there is oil fumes ect so the mixture wont fire? Still the original umberlla valves in the rocker box? Have you done a compression test on it?   Bob

[Tom H]

Stock setup. Changed the little hoses from the head vent bolts to the air filter because they had cracks. Dose not appear to have any leaks around the bolts. But it has "always" left me a drip under the air cleaner until I clean the air cleaner up. Then a some?? months latter I have to clean again. Could be 6 months?

I'm kinda new to HD, been working on Italian brand for many years. Umbrella valve???

EDIT: When I pulled the air cleaner off when the issue happened last, everything looked clean. No excessive oil residue. My fingers were clean after messing with the air cleaner.

Tom

[FXDBI]

Stock setup. Changed the little hoses from the head vent bolts to the air filter because they had cracks. Dose not appear to have any leaks around the bolts. But it has "always" left me a drip under the air cleaner until I clean the air cleaner up. Then a some?? months latter I have to clean again. Could be 6 months?

I'm kinda new to HD, been working on Italian bikes for many years. Umbrella valve???

Tom

Vents in the bottom rocker box for the heads and engine. Your air cleaner getting oil in it is from the carryover in the vent lines. I would still brake clean the TB if this is occurring regardless if it looks clean. Welcome the the world of HD. I see your new here has well my advice to you is get a drink and sit and read all you can here. Its the greatest book of knowledge ANYWHERE on HD motorcycles. Externally venting those heads will prevent a lot of problems later.   Bob

[Tom H]

Is there some sort of flapper valve in the rocker box?

When I have had questions about this bike, web search was my friend. Normally could find answers that my Factory and Chilton's manual couldn't give me a clear answer.

This is about the second time that I have posted in a HD forum. This issue is confusing. I'm fairly comfortable with Moto Guzzi FI and it's Ido/Idiot-synchrocies.

I know that a shut down engine can "cook" components. Component can work perfect "moving" down the road, then "cook" and fail intermittently.

I do appreciate the help!!!!!!!!!! I will work through all suggestions. I just kinda figured that someone has been there and it turned out to be the ?? I would just buy  the ?? and replace it.

I'm starting to think the crank sensor purchase is in my future.

Thanks very much again so far!!!
Tom

[Ohio HD]

The breather valves are in between the rocker arms just under the rocker cover. If yours are original they should look like these. If they've been replaced, they may look like the lower image.


EARLY STYLE



LATE STYLE

[Hossamania]

I would lean toward crank position sensor and temperature sensor. As mentioned, clean up the throttle body.
New plugs might not hurt either.
Next time it happens, try turning the key on, 2 seconds, key off, key on, key off, key on, key off, key on and try starting.

[Tom H]

I did try cycling the key and kill switch many times while trying to get it started. That would be to simple to diagnose and fix.

Thank you for the images. I would guess I have the original style. Do they need to be cleaned or replaced every so often. Or is it just better to close off the vent in the  bolt and do one of the changes to make the engine vent to ground?

Thanks you all again so far!!!!!!!
Tom

[FXDBI]

I have a 2006 Dyna. First time I had hot start issues heads were vented to the TB. Vented them to the ground and cleaned the TB real good, problem solved. Next year hot start problem did a oil change and pulled crank sensor it was filthy. Cleaned and re-installed problem gone. Head vents had a good drip that fall re moved engine re-built to 95cu in with my heads re-worked. Hot start problem, replaced battery with 720amp anti-gravity lithium battery end of problem for years now. Even re-worked to a 110 it spins over and starts hot on the touch of the button.  Bob

[Tom H]

Sounds like a battery solved your issue if I'm reading right.

For the crank sensor. I searched for one. Prices varied. For instance a major prime member site had them for about $28 or a bit more. But they were made overseas. I'm guessing that the dealers part would also be made there. Is there any reason not to go with the prime member site?

Sorry, don't know the rules here about mentioning name brands of things, especially if you don't particularly care for that brand.

Thanks everybody again!!
Tom

[Hossamania]

I vent mine to ground, I don't like the idea of all that oil blow-by being sucked through the throttle body or carb into the motor. Keeps the TB much cleaner. There are quite a few posts showing methods to do the external venting.
There is no need to disassemble and clean the umbrella valves. Put your finger over the breathers while the bike is running, you should feel the air pulses pushing out. If they suck in, there are issues. They could occasionally be replaced, mine have 100,000 miles and seem to be working fine.

[Tom H]

Once I looked at a picture of it, it's basically a PCV valve. My BMW uses one similar to the HD.

Before I change the venting, yes I have read about numerous way of doing it, even venting into the top cover of the trans. Since my last oil change a few weeks ago, I'm runnig the oil level about half way on the dipstick or just a little less. Read that this can help the oil in the filter. This does work on my Guzzies.

I think I will try a crank sensor. Again, any reason not to just grab one from the web site I mentioned?

Thank you very much again!!!!
Tom

[Ohio HD]

My mind is backwards, I originally said suck against the hose. You want to blow into the hose to see that the valve doesn't suck air inwards. 

I like the OEM crank sensors. I have more faith in them. 

[smoserx1]

Once I looked at a picture of it, it's basically a PCV valve. My BMW uses one similar to the HD.

Exactly.  That is the theory of it and I have always kept mine hooked up contrary to many who vent to the ground.  It does not seem to hurt cars and seems to me like the slight amount of oil mist going back into the engine would help upper cylinder lubrication.  It will increase carbon in the combustion chamber however.

You said you had spark when this no-start occurred.  With a bad crank sensor you should not get a spark.  Sounds like your engine is flooding (mine will do the exact same thing occasionally but I have a carburetor).  KD's explanation seems the most probable to me and I know Harley has had issues with fuel tanks venting in the past.  The simplest solution is to drill a tiny pinhole through the diaphragm of the gas cap.  If you don't want to mess up your 'H-D" gas cap, a  generic one will fit just fine.

Whenever mine floods I hold the throttle wide open when cranking and it starts right up every time.  Next time you get a no-start issue try that.  If it starts up you know what your issue is.

[Hossamania]

Before I change the venting, yes I have read about numerous way of doing it, even venting into the top cover of the trans.

If you set up a catch can and see the shmutz that comes out of the tube, you would not be a fan of putting that crap into your transmission, a mixture of water and oil.

[Tom H]

I did try holding the throttle wide open a few times. With the air cleaner removed, I was about 3/4 open when it finally did start. But....I'm now thinking it was more that it had time to cool of a bit.

I'm not a fan of venting to the trans. I just mentioned it. If/when I do change the venting, it would either just be to ground or a catch can.

Thanks again!!
Tom

[fbn ent]

NEVER to the transmission. That's just dumb  .

[Tom H]

I've been giving more thought as to what happened just before I shut it off.

I was in a parking lot looking for a spot, probably first gear. Saw a spot open behind me and made a u turn. The isle is slightly down hill to the open spot. While off throttle and in gear turning into the spot, I vaguely remember hearing some popping from the exhaust. Not big backfires, just a popping. I was thinking that's odd, don't remember it ever doing that. Remember I'm in a parking lot, so my full attention was not on how the bike was running, more on the traffic.

So now this has me thinking.

Crank sensor. I think they normally work or they don't?? While in no start issue. I did pull a plug cap and put a screwdriver in it. Held it near the head, cranked and got a spark. Cap back on plug and still no start. No start for at least 5, probably more minutes.

Now I'm starting to think the temp sensor as KD mentioned. Could it really throw the fueling off that much that it would act flooded??? Is there a way to test it while cold?

Thanks again!!!!
Tom

[Coyote]

Could it really throw the fueling off that much that it would act flooded???

Yes

Is there a way to test it while cold?

Yes, you can measure the sensor resistance as it warms up (in the service manual) or monitor the reading using a tuning device.

[Tom H]

Thank you for that info. I did look at the manual to see where the temp sensor was. I didn't notice anything about testing it, just replacing. I'll have too look again, must be in there somewhere.

Thanks again!
Tom

[Coyote]

Thank you for that info. I did look at the manual to see where the temp sensor was. I didn't notice anything about testing it, just replacing. I'll have too look again, must be in there somewhere.

Thanks again!
Tom

It's in the EDM

[Hossamania]

Throttle wide open at start puts it in flood mode and shuts off fuel, theoretically.

[kd]

The ETS tells the ECM that the engine is getting hot.  The ECM then fattens out the fuel mixture to remove any lean conditions and that typically cools the engine.  It also can cause fuel smell and carbon in the exhaust tip(s).   If the ETS is failing but not to the extreme yet you may get the type of symptom that you are describing (or worse).  The risk is that once started, it can tip over completely at any time and leave you stranded so your quick attention to it is a good thing. 

Because it doesn't throw a code, many just change it.   If you can, do the test procedure as Coyote suggested. If you decide to just change it and it works, all is good.   If it doesn't help, you have a spare to take with you.   Either way, it's  a high probability fairly common item with your symptoms.   Waiting too long may confirm it for you when you're down the road somewhere. 

[Tom H]

If the EDM is the electronics manual. don't have one. Maybe I can search for the specs online.

I decided to order the ETS. As I mentioned. kinda ruling out crank sensor since I was getting spark. Should be here in a day or two.

Unfortunately, this issue does not seem to come up on demand. So it will be just riding it and do some freeway and then stops to see what happens. If it does or does not help, I will update this thread in case someone else has my symptoms and this helps them.

Thank you very much!!!!
Tom

PS: might just be hanging around here a bit. Lots of great info!

[Hossamania]

Good luck, hope that solves your problem.

[Coyote]

If the EDM is the electronics manual. don't have one. Maybe I can search for the specs online.

I decided to order the ETS. As I mentioned. kinda ruling out crank sensor since I was getting spark. Should be here in a day or two.

Unfortunately, this issue does not seem to come up on demand. So it will be just riding it and do some freeway and then stops to see what happens. If it does or does not help, I will update this thread in case someone else has my symptoms and this helps them.

Thank you very much!!!!
Tom

PS: might just be hanging around here a bit. Lots of great info!

[Tom H]

Thank you for the table!!

Tom

[Tom H]

After replacing the engine temp sensor and taking the bike out for a ride that "may" have made it have the issue, so far so good.

"Seemed" to start a bit easier when hot after about a 1/2 hour freeway ride. Tried it twice right away, then about 20 minutes latter twice again. Both times it fired up right away.

Also, when I got home after another 1/2 hour ride, the engine "seemed" to be a bit cooler (with about the same air temps) than it has been. Could just be wishful thinking and my imagination. I didn't seem to feel as much heat off of it at traffic lights. Normally chestnuts seemed to be roasting over an open fire .  Cool down time after the ride seemed to have less pings and pops that it normally has been since I've owned it.

Still...Time will tell if the issue comes up again.

If it does, maybe a sticky injector. Though, the bike runs just fine in all air temps. Except for a tad bit of ping in 6th at about 65mph when I want to make a quick pass in traffic, bit of pinging. Probably should have grabbed 5th. Could also be a lean factory map in the ECU?

I'll update again latter.

Thank you all!!!!!!
Tom

[Hossamania]

Were it an automatic transmission at 65mph in 6th gear and you hammered it a bit, it would have gone to 5th gear and probably 4th right away. The little bit of ping you had was not abnormal.
Good luck, hopefully you got the problem sorted with the new sensor.
Go ride and have fun! (I'm jealous, as it is -2°F right now with 6" of snow today, more tomorrow.)

[Hossamania]

.

[Tom H]

That's what I figured on gear selection, should have grabbed 5th.

Brrrr. Sorry. Glad I'm in So Cal. 40 at night and "I" think "it's" cold.

Thanks again!!
Tom

[Tom H]

I haven't gotten out much due to rain. But I've had it out a coupla times. So far it's been good until today.

Started fine a few times even after a freeway ride that gave it trouble before. Then I headed home with just a city street drive. Shut it down to for a bit to get my gear off and open the garage, maybe 10 minutes. Had the no start issue for a short crank and stinky exhaust. Then the next crank it sounded like it was on one cylinder and stalled. Next did the same. Then it started on the 4th after a short crank. Got in the garage and 5 times in a row it fired up in a turn over or two like it should.

More riding time needed to see what happens. Any thoughts??

Thanks again!
Tom

[Tom H]

An update.

I ended up changing my injectors. Bought a set on fleabay that claimed OEM spec. The originals looked a bit dirty, even though they have maybe 20K miles on them.

Again, not enough test time yet to know it that solved my issue. So far so good though. But the weather has been on the cool side. When the weather warms up, it may get the issue?

I'll update as this latter.

Tom

[tdrglide]

I hate intermittent problems. In my limited experience they have been wiring issue. Weak connection or break in wire inside insulation. Would loose continuity when temps were hot. Found problem with ohm meter and wiggling wires

[Tom H]

Your right. Intermittent issues are a pain. That's why this one is taking so long to be sure the temp sensor or the injectors has solved it.

Could have been as simple as an injector would intermittently get stuck open.

Thank you!
Tom

[Tom H]

Well it appears that new injectors has fixed my issue.

So far it has been fine since I changed the injectors. Even in the heat we have had lately where it would have had it's issue, it's been fine. Only 1 minor hiccup when I shut down, started it right away and then shut down again about 20' latter. Withing about a minute I started it again and it acted like it was missing? Then it quickly cleared up.

Thanks again!
Tom