Oil Change followed by misfire - WTF?

[CoreyL]

Today was one of those days that makes you happy to live in South Central Texas; 75 degrees with cloudless sky of azure blue.

 

Anyway, we did a little 200 mile ride for lunch out to Utopia TX I was on my 2001 V11 Sport, with a couple of friends on a Quota and a 750 Breva.

 

It was about time for an oil change so, when I got home, I shut off the bike and rolled it into the garage. I put the bike on a stand, removed the drain plug, ;et the oil drain and took out the old oil filter. Once the oil had stopped dripping out, I replaced the drain plug, and put in a new oil filter (pre-filled with oil). I refilled the sump and started the bike to circulate the oil before checking the level.

 

To my puzzlement, the bike ran like crap! Backfiring, it wouldn't idle and stalled when I tried to give it some gas. I pulled the plugs and put in a fresh pair: no improvement. I next verified that I had good spark: yes. I also checked compression: both cylinders good. I did notice burbling sounds coming from the gas tank after the fuel pump came on, so I tried running the bike with the fuel filler cap open: no improvement.

 

At this point, I'm stumped. I can't figure out what changed between going on an troublefree 200 mile ride and then re-starting the bike after an oil change.

 

Anyone have any idea of what's going on?

 

Thanks in advance for any input.

[Steve G.]

This sounds like a heat related issue with the fuel system, caused by the engine superheating the fuel lines around the cylinder. Lets call it vapour lock. To fix this short term, you will have to "burp" the vapourisation from the fuel line from the fuel tank on/off switch/lever. Not sure which one you have, but probably the electric one. Loosen the hose clamp from the tank outlet, and it should start to vent air with some gasoline bubbling as well. Release this vapour, and all will be well.

Long term, you will have to check the routing of your fuel lines to make sure none of them are near either of the two cylinders. Then try to wrap the fuel pump in the same material you find glued to the underside of the fuel tank.

I had exactly the same issues you had with the running. If you wait, it will start when the fuel system gets cold, about an hour. But it will happen regularly if you don't get rid of the vapour. I have no such problems now that I have routed the lines away from the heat sources of the engine, namely the cylinders.

Ciao, Steve G.

[richard100t]

Now thats a real head scratcher I'd let it cool down to room temperature & see if it still runs poorly. My only guess is that you may have inadvertently loosened a vacuum line or loosened a wire. The thing is I dont know of anything like that, that could come loose from an oil change. Dont worry someone here will have a good idea of whats up. Btw I have #74 nice valve cover guards

[Guest ratchethack]

Corey, this is a bit of a baffler without more info. I wouldn't make the common mistake of assuming that the symptoms are related to anything you did changing the oil. By your post, there's no reason to tie the two in a cause-and-effect relationship.

 

You didn't indicate that you'd done any modifications. If so this may be significant. How many miles? All scheduled services up to date? One backfire can blow off an intake rubber. They tend to degrade slightly over time via ozone and Uv attack, and the clamps should be snugged up periodically, or a backfire will blow 'em off.

 

That's all I got without more info, sorry.

[CoreyL]

The bike has about 13K miles.

 

All the cannisters and hoses have been removed. I have K&N pods on the injector bodies. I'm also running a Power Commander. Stucchi crossover and Mistral pipes.

 

I agree that the problem does not seem to be related to the oil change in a cause and effect way.

 

The heat induced fuel delivery problem sounds like it might be the problem. I will try to start the beast up again after it's cooled completely.

 

I've had the bike for several years and done many oil changes, and, even during today's ride, there were many times when I stopped, shut the bike off for a few minutes (waiting for others to catch up) and then restarted without incident. Maybe while in the garage with no air movement, heat was getting trapped up under the tank or in the vicinity of the fuel lines.

[Guest ratchethack]

IMHO, it's highly unlikely that vapor lock would occur after cooling the length of time it takes to change the oil - particularly if, as you indicated, you never had symptoms of VL before.

 

Did you check the intake rubbers?

[CoreyL]

OK. I just went out to the garage to check the intake rubbers: they're fine.

 

The bike was cool so I fired it up and it ran fine. So, the problem appears to be heat-related.

 

Next step is to take a close look at routing of fuel lines and try to insulate things.

 

Thanks to all who responded!

[Ouiji Veck]

Corey, this is a bit of a baffler without more info.  I wouldn't make the common mistake of assuming that the symptoms are related to anything you did changing the oil.  By your post, there's no reason to tie the two in a cause-and-effect relationship. 

 

You didn't indicate that you'd done any modifications.  If so this may be significant.  How many miles?  All scheduled services up to date?  One backfire can blow off an intake rubber.  They tend to degrade slightly over time via ozone and Uv attack, and the clamps should be snugged up periodically, or a backfire will blow 'em off.

 

That's all I got without more info, sorry.

72934[/snapback]

My first guess too ratchet...intake boot got blew off.

It's happened to me twice.....Ya get the few seconds of a panic attack

then do the while your buddies just roll thier eyes.

Intended to REALLY clamp those babys on last time but my "mechanic sevant"

(in green t-shirt)

indicated a blown off boot shure beats a bent throttle plate. yea it does...

[Van]

Slightly off topic l know but......

you mentioned that you put your bike on a stand, what do you use???

l got a low cost stand from Canadian Tire (sort of like your pep-boys) and want to modify it, any thoughts??

Cheers

Van

[Steve G.]

IMHO, it's highly unlikely that vapor lock would occur after cooling the length of time it takes to change the oil - particularly if, as you indicated, you never had symptoms of VL before.

 

Did you check the intake rubbers?

72937[/snapback]

IMHO, the time it takes to do a quick oil change is the perfect amount of time it takes to superheat the fuel system to cause a VL. As well, IMHO, it was the VL which caused the lean condition, which caused the backfire. Common sense and understanding of a basic engines needs would make a person read the backfire as a symptom of an outstanding problem. Thinking it's the intake rubbers only is just treating the symptom.

This is a problem that predominates with pre-'02 bikes that has been talked about before, and is just now being understood more. Ryan [badmotogoozer] has a great understanding of it, and came up with the great idea of reducing the pump temperature by wrapping it, and the fuel lines in a temperature reducing product from the aeroplane field.

Ciao, Steve G.

[al_roethlisberger]

IMHO, the time it takes to do a quick oil change is the perfect amount of time it takes to superheat the fuel system to cause a VL. As well, IMHO, it was the VL which caused the lean condition, which caused the backfire. Common sense and understanding of a basic engines needs would make a person read the backfire as a symptom of an outstanding problem. Thinking it's the intake rubbers only is just treating the symptom.

This is a problem that predominates with pre-'02 bikes that has been talked about before, and is just now being understood more. Ryan [badmotogoozer] has a great understanding of it, and came up with the great idea of reducing the pump temperature by wrapping it, and the fuel lines in a temperature reducing product from the aeroplane field.

                                                                          Ciao, Steve G.

72948[/snapback]

 

 

*if* VL related, and *if* interested

 

Vapor Lock FAQ

 

 

....I spent months and months researching this, shielding pumps and lines, and even relocating the pump. Ultimately the only real/sure solution is to ditch the external system and go with a 2003+ tank.

 

However, shielding the pump, and making certain the fuel lines are not in close proximity to the "hot bits" can help. Also, moving the pump to the old Sport-1100i/Centauro location "out front" of the engine seems to cure this problem.

 

Good luck

[Alex-Corsa]

*if* VL related, and *if* interested 

Also, moving the pump to the old Sport-1100i/Centauro location "out front" of the engine seems to cure this problem.

 

Good luck 

Perhaps it does , I never had this kind of problem in my Sport-i in the over 40K km I have it and driven in most any conditions.

[Guest ratchethack]

IMHO, the time it takes to do a quick oil change is the perfect amount of time it takes to superheat the fuel system to cause a VL. As well, IMHO, it was the VL which caused the lean condition, which caused the backfire. Common sense and understanding of a basic engines needs would make a person read the backfire as a symptom of an outstanding problem. Thinking it's the intake rubbers only is just treating the symptom.

This is a problem that predominates with pre-'02 bikes that has been talked about before, and is just now being understood more.

Steve, I didn't realize that an opinion that differed with yours would provoke offense. I'm truly sorry if I offended you. That was not my intent. Of course you could be right about heat-caused symptoms. It's a little difficult to diagnose things over a Forum post, and you have to make assumptions, or there's little potential of finding a workable solution. Wouldn't you agree? I was just offering one possibility. Troubleshooting is a game of probabilities. Is there no room here for different points of view when trying to help out a guy with a problem without offense being taken?

 

Common sense and a fairly thorough understanding of basic engine operation IMHO would tell me the following:

 

1. I also prefer to have my engine at full operating temp prior to an oil change. By the time I've allowed the old oil to stop dripping, pre-filled the new and changed out the old filter, and refilled and checked the level, as Corey had indicated, my engine is cool enough to the touch that I can comfortably hold my hand on any part of the cylinder heads - or anywhere else on or around the engine - with no problem. By this time, the fuel lines and TBs are relatively cool to the touch. Common sense tells me that at this point, neither the fuel pump nor any part of the fuel delivery plumbing have anywhere near enough heat to vaporize fuel. Even if you have a bike that's already known to be prone to heat-soak induced VL, AND you change your oil and filter immediately after shutting down after a long hard run (again - waiting for the old oil to stop dripping!) - if you did it racing against the clock, it might be possible to do it fast enough to still have enough heat somewhere in the fuel system for vapor lock to occur, but common sense and experience tell me it's exactly as I said in my post - highly unlikely.

 

2. My Guzzi and my friend's LeMans have both very occasionally and very briefly coughed back through the TBs for unknown (not very important, IMHO) reasons starting up from cold, obviously unrelated to vapor lock. As in Corey's case, neither bike has ever had any non-start or lean-condition symptoms that would be consistent with vapor lock, in every conceivable heat-soak condition - even on 100F+ days. Common sense tells me that the cough-back (backfire, if you will) that blew off my pal's intake boot and caused symptoms identical to what Corey described might have happened to him, too.

 

3. I'm fully aware that many Guzzi models have experienced chronic vapor lock symptoms. Corey indicated he's never experienced it before. I've got 27K miles without any such symptoms and 2 fellow V11 owners I know (also with pre-'02 V11 Guzzi's) have also never experienced it. Common sense tells me that the liklihood of it suddenly appearing for the first time on a relatively "cooler" winter day, even where he lives, would be very low - especially after cooling down for the time it takes to do an oil change - though it's certainly not impossible!!

 

Common sense also tells me that when an intake boot pops off from an engine cough, continuing to try to start it (as happened to my pal), the cause of the cough-back is now irrelevant, because now the cause of the lean symptoms and non-start condition is a blown-off intake boot! Experience tells me that this happens with lots of bikes (BTDT). Common sense tells me that it's well worth checking when the symptoms line up. It's easy enough to do...

 

As far as common sense and basic understanding of engine operation making a person read a backfire as a symptom of an outstanding problem, I would have to disagree here. I've owned a dozen bikes of all sizes and configurations, I've partially or completely rebuilt many of 'em, and I've tuned 'em all myself. I believe that at some point, very likely every one of the four-stroke bikes coughed-back, even while in a high state of tune. Unless you consider the inherent design of many engines itself "problematic" enough to allow a very occasional hiccup, I reckon common sense would tell you NOT to make an assumption that there's necessarily an "outstanding problem" every time it happens.

 

Common sense also tells me that Guzzi's - like any IC engine, can occasionally seem to defy common sense.

 

BAA TJM & YMMV

[dlaing]

My money is on relays.

I suppose the coils, spark plugs, leads, etc. could be bad, too.

Or bad gas...

Or an intake leak

Or an exhaust leak

Or vapor lock

Or...

[CoreyL]

Slightly off topic l know but......

you mentioned that you put your bike on a stand, what do you use???

l got a low cost stand from Canadian Tire (sort of like your pep-boys) and want to modify it, any thoughts??

Cheers

Van

72946[/snapback]

 

 

I started with one of the "factory" stands that I got from Mike Haven at MPH. It's one of those units that you slide under the bike from the rear and it levers the rear end of the bike up in the air, using the two nuts on the hambone footrest plate as supports. I use it when I need to be able to rotate or remove the rear wheel.

 

I later bought one of the those LA Sport Chocks (http://www.baxleycompanies.com/Sportchock.html) which I now use routinely. It's great; you just roll the bike onto the stand and that's it. The bike is upright, the rear wheel is not off the ground, but for oil changes, other maintenance and just parking the bike in the garage (or in the bed of a truck) it's great.

 

I apologize since this information may not help you much with modifying the unit you now have, but I thought I'd pass along my experience with the two stands I have now.