Vapor lock, most unfun

[raz]

But this intake side discussion has me confused. As far as I know, when the pump is not running it essentially blocks the line. That is, with an open petcock, there is only gravity pressure on the left side when the pump stops, while the pressure on the right side remains (for a while). I can't figure out why burping left side would solve anything.

Ah, it seems you have the petcock on the right and the FPR on the left. Never mind me

 

Edit: no... wtf. In the WHB for V11 Sport, the pictures show petcock at the right and FPR at the left, but the text says the other way round. I guess we just can't talk about right and left but petcock and regulator.

[ALdad]

You say in the other thread no fuel comes out when you remove the hose. That's another wierd story but I can't think of any other explanation for it than that the pump can actually overcome the solenoid valve.

When I remove the hose at the solenoid, fuel and pressure comes out of the hose, Not the solenoid. The pump stronger than the solenoid sound possible. I have not tried to break the tank vacumme via the gas cap, with the hose disconneced to see if gas free flows out the solenoid. I will try that tonight.

[raz]

 

Let's continue the discussion from this picture, regardless of what is left and right on a real bike. Where do you burp?

[raz]

When I remove the hose at the solenoid, fuel and pressure comes out of the hose, Not the solenoid. The pump stronger than the solenoid sound possible. I have not tried to break the tank vacumme via the gas cap, with the hose disconneced to see if gas free flows out the solenoid. I will try that tonight.

Unless your bikes are totally different from all I know, there should be no pressure there. With pump running, this hose will probably contain a lower pressure than ambient air. Especially if it has to overcome a solenoid valve...

 

Pardon a stupid question but you are not talking about the pressure regulator side are you? That one will behave like you say. But then the broken wire would not be on that thing.

[jtucker]

It seems it's been 6 or 7 years since this problem was first reported here on the forum, and we're still no closer to a fix. Well, short of getting a newer bike with the in-tank pump, that is...

 

I too thought the manual petcock might fix the problem, which is why I had one installed during my rebuild project. Sadly, anecdotal evidence here seems to suggest that was futile. I've also wrapped my fuel lines in aluminized insulation... not sure if it helps or not, though. Time will tell if any of the things I did had any effect. Or maybe it won't. The strange thing is, my bike ran fine for about a year or so with NO vapor lock issues at all, and then suddenly it started happening fairly regularly (change in fuel formulation? )

 

When the problem happens, there is a very noticeable change in the pitch of the fuel pump. I always assumed this was because the pump was sucking vapor rather than liquid, and that once it sucked vapor it was useless until it was "primed" again (somehow). I had thought - possibly incorrectly - that allowing the petcock to vent while the bike was parked might fix this condition. Hmmmph.

 

I guess the question I have now is: What actually causes the change in pump "pitch". Is this really because it is trying to pump vapor? Or, is it something else. The only other "else" I can think of is that it is encountering resistance on the regulator side... like a blockage shortly after the pump (or in the pump?).

 

Just thinking out loud here. Since I got my bike back on the road, I haven't experienced any really hot days yet. If I keep having problems - despite my cheap & lazy attempts to fix - I may start investigating a bit further. I've got a fuel pressure gauge kicking around here someplace, and might consider hooking it up to try and get some empirical data - like, when the pump spins up, does the fuel pressure actually increase, or not. The fact that the pump shuts off leads me to believe that there is, in fact, a pressure build-up, but who the hell knows.

 

Maybe next time it happens, I'll just pull out my trusty V11 voodoo doll and start poking needles in it. Seems about as plausible a fix as anything else, no?

 

__Jason

[raz]

The pump is not ever pressure controlled; when the engine is running, the pump runs continously. The reason it does run for a couple of seconds when turning ignition on is just for priming. So the fact it stops does not mean the pressure increased.

 

One thing I would try if I had the problem, is jumping the fuel pump relay so it runs until the sound changes. I've jumped the pump for other reasons, it's very easy. On my bike, just remove the power relay and short the NO terminals (numbered 30 and 87). Running the pump with engine off is completely harmless except you could drain your battery. That would take a very long time though, the load is about the same as a headlight.

 

I don't even have the problem, but I find it interesting. I never heard of any Sportis having it - that is something one could delve deeper into. I think the reason the problem goes away for a long time and then comes back may be in Fuelcooler's post here, alkylates. There is also good info at wikipedia. But those are just general background info. What is more interesting is why some have it and some don't.

[jtucker]

Good info, Raz - thanks for that. I'm going to keep this "pump jump" in mind.

 

As for why it happens to some, and not others? Who knows? Why do some V11s ping, while others do not (BTW.. before my rebuild, mine pinged... not any more!). As the folks trying to set up their TPS seem to be finding out, each one of these bikes seems to have its own "special" characteristics. Perhaps some bikes are running hotter than others for some reason, which makes them more susceptible to vaporizing the fuel in the lines.

 

There is tremendous opportunity for a science project here, if only someone had enough time, gumption, and access to a pool of V11 "test subjects".

 

__Jason

[Guest frankdugo]

my gm engineer buddy rpeterson suggested wraping the fuel pump with space blanket material, like gm does with their starters that are close to exhaust.been meaning to try it ,haven't got around to it yet. ps, his 00 quota champange&blue won best of class at "riding thru time" bike show last week.

[ALdad]

 

Let's continue the discussion from this picture, regardless of what is left and right on a real bike. Where do you burp?

This is weird. My 2000 is opposite of this picture. My fuel pump is on the bottom and the solenoid is on the left, when sitting on the bike. Anyway I ordered a manual petcock should have it in a couple of days. That will fix the broken wire concern ,and maybe help with the vapor thing. I am also going to insulate with fire sleeve.

[Steve G.]

 

Let's continue the discussion from this picture, regardless of what is left and right on a real bike. Where do you burp?

 

 

I've always burped mine at component #4, the line that goes to it. And it's on the left side of my bike.

I drain ALL the pressure off of here to fix it.

Don't ask me why, but it does cure the problem.

?????

Steve

[ALdad]

I've always burped mine at component #4, the line that goes to it. And it's on the left side of my bike.

I drain ALL the pressure off of here to fix it.

Don't ask me why, but it does cure the problem.

?????

Steve

That's the pressure adjuster. on my bike it is on the rt. side. Those crazy guzzi guys always changing it up just to keep us on our toes. I will burp it from the pressure valve next time, and see if it works any better. It's easier to remove that hose anyway and makes more sence since it is at the end of the line. Cheer!!

[dlaing]

That's the pressure adjuster. on my bike it is on the rt. side. Those crazy guzzi guys always changing it up just to keep us on our toes. I will burp it from the pressure valve next time, and see if it works any better. It's easier to remove that hose anyway and makes more sence since it is at the end of the line. Cheer!!

If you carry a hose to fit the vacuum line, it could be a lot easier to activate the relief valve to reduce pressure than to detach and reattach the fuel lines...assuming it works.

I ALMOST wish I had the problem so I could test it.

Of course it won't lower the pressure as much as detaching the fuel lines, but if it does the trick, you will be a happy camper, with no gas all over your hands

Don't suck on it too hard. I suppose it is possible for the diaphragm to rupture and for you to get a lung full of gas.

As I said, our lungs can create about 200mm HG and only 20mm Hg is necessary. There was talk that the pulse of the engine could damage the diaphragm. If that is the case, than maybe 200mm Hg can damage the diaphragm too.

Just suck it like drinking a sodapop with a straw, not like drinking a thick milk shake through a straw.

[Admin Jaap]

There is a solution! Use the Tenni gas pump layout above the oil-cooler and I think you're sorted. I somehow have this setup on my bike thanks to Luigi. (I think it was supposed to become a Tenni, but they decided to fit the normal Le Mans bodywork). As I don't have the oil cooler anymore I can't take a new pic.

 

This mod could look easier than it is. Rererouting fuel lines, making new brackets for the oil-cooler and pump and probably a lot more I can't foresee...

[nose2wind]

I had this problem years ago and fixed it by locating the pump where the filter is and filter to pump location. I did a write up with pictures.

 

If you need to burp the line just disconnect the line at the petcock to the pump.

 

good luck.

[ALdad]

I had this problem years ago and fixed it by locating the pump where the filter is and filter to pump location. I did a write up with pictures.

 

If you need to burp the line just disconnect the line at the petcock to the pump.

 

good luck.

Was your pump on the top or bottom? Where is it now? Petcock to pump is where I have been burping. Sooo many opinions.