V11 Vapor Lock or Something Worse?

[Steve G.]

SOunds like a bad petcock or a venting issue. Do you still have the electric petcock? If so, replace it with a manual petcock. Leave the manual one open all the time unless removing the tank. While you are in there, re-route or shield hoses to reduce the tendency to vapor-lock.

 

 

I have much experience with this issue, and had exactly the symptoms you have. Here's what's happening. Collective hot starts have built up the vapourized gas to a volume big enough that the fuel pump is now cavitating in 'air'. Short term but instant fix, you will have to "burp" the pressurized vapour [pressurized because the electric fuel pump your bike has shuts closed the moment you turn the ignition off] where the fuel line meets the bottom of the fuel petcock. It will hiss at you even when the thing is turned off. Once hissing and possible gurgling of fuel/vapour stops, your good to go for perhaps 10-20 hot starts where the problems will start again.

As Greg mentioned about the manual petcock, what I'm sure happens is, installing a manual petcock eliminates the collection of vapourized gas, any super heated gas which chooses to vapourize inside the fuel line right near the inside left cylinder simply vapourizes and bubbles up through the still open manual petcock up into the fuel tank harmlessly. The electric one traps this.

You could go a step further to eliminate this issue, by getting a product called 'Firesleeve', a fuel line insulator used primarily in aircraft, which will vastly reduce the heat issue inside that area behind the left cylinder.

 

Steve

[ScottS]

I have much experience with this issue, and had exactly the symptoms you have. Here's what's happening. Collective hot starts have built up the vapourized gas to a volume big enough that the fuel pump is now cavitating in 'air'. Short term but instant fix, you will have to "burp" the pressurized vapour [pressurized because the electric fuel pump your bike has shuts closed the moment you turn the ignition off] where the fuel line meets the bottom of the fuel petcock. It will hiss at you even when the thing is turned off. Once hissing and possible gurgling of fuel/vapour stops, your good to go for perhaps 10-20 hot starts where the problems will start again.

As Greg mentioned about the manual petcock, what I'm sure happens is, installing a manual petcock eliminates the collection of vapourized gas, any super heated gas which chooses to vapourize inside the fuel line right near the inside left cylinder simply vapourizes and bubbles up through the still open manual petcock up into the fuel tank harmlessly. The electric one traps this.

You could go a step further to eliminate this issue, by getting a product called 'Firesleeve', a fuel line insulator used primarily in aircraft, which will vastly reduce the heat issue inside that area behind the left cylinder.

 

Steve

 

Thanks Steve for the analysis. Hwo do you burp the line ? Do you carry a tool to be able to take the line loose ? As a test , the other day I spritzed the engine down with water when it was in a no- start conidtion, and it fired right up. I even can tell the difference now when the pump runs in air vs in fuel.

[Guest ratchethack]

. . .the other day I spritzed the engine down with water when it was in a no- start conidtion, and it fired right up. I even can tell the difference now when the pump runs in air vs in fuel.

Best be careful about throwing water on a hot engine!

 

Not saying that this would NECESSARILY happen on an alu Guzzi block, barrel, or head, (or any other moto, for that matter) but doing this on a cast iron engine block has been known to instantly convert it into a multi-piece part.

 

Yeah, I know -- many's the offroad moto that's survived a splash in a stream without incident. BTDT many times.

 

I wouldn't tempt fate with the Guzzi donk.

 

But o' course, that's just me.

 

EDIT: The effect of raindrops is much different than splashing water on one area of a motor.

[ScottS]

Oh and does anyone have thepart # fort the manual petcock- my local dealer wasnt able to figure it out - maybe someone can direct me to a parts vendor that is prefrerred

[gstallons]

You need to call Joe Eish in Salineville,Oh. 330-738-3944

[Steve G.]

Thanks Steve for the analysis. Hwo do you burp the line ? Do you carry a tool to be able to take the line loose ? As a test , the other day I spritzed the engine down with water when it was in a no- start conidtion, and it fired right up. I even can tell the difference now when the pump runs in air vs in fuel.

 

 

Hi Scott, as Ratchet mentions, cold water on a hot engine could cause metal warping or cracking in extreme cases. I've actually seen it happen with cast iron engines, never aluminium, but who knows. I must admit I did the same thing 3 yrs ago in the middle of nowhere [Midway, B.C.], totally pissed at the bike, didn't care if I cracked the engine, found a hose at a gas station, sprayed it up on the external pump & lines, fired right up.

The term 'burping' I used when I first started poking around with the bike on the side of the road one hot August afternoon with my buddies watching. A slotted screwdriver is enough to loosen the hose clamp coming off the bottom of the petcock. You may have to pull the line right off to release, but I just kind of spun the hose on the petcock orfice, that was enough to start releasing pressure, mostly atomized fuel [air] but there may be some liquid gasoline spit out as well, so be carefull where it lands if the engine is hot, if you know what I mean.

Check with Greg Field or Pete Roper on this forum, but I'm pretty sure that 1999, 2000. and 2001 V11's had the electric petcock, after that, manual petcocks were exclusively used. Why they went electric I'd like to know, it was stupid fucking idea. The manual petcock is quite inexpensive, I rode down from Vancouver to Moto International in Seattle one day to get one, Greg had them in stock. I'd get rid of the electric one for other reasons besides the vapour entrapement issue. The wires at the bottom of it are not very big, and vibration damage can cause the fuel delivery to stop, yet you'll never see the wire broken inside the isloator, exactly what happened to me, twice, both covered by warranty in the early 2000's. My local dealer, British Italian in Vancouver, would not upgrade [the manual one's actually cheaper] to the manual, so I had to play the game Moto Guzzi used to play during the Aprilia years.

 

Steve

[kevdog3019]

My '03 cut out the other week when sitting at a light in pretty hot weather. I rested in the shade awhile and it started up. As I took off down the road at 35 mph it once again cut out. From that point on I couldn't get the fuel pump to dance upon turning the key. I opened the tank twice, have never had vapor lock anyhow EVER, and no pressure. The fuses are all fine and the relays are new and are fine. They click when I turn the key on. Why is my pump not working? Any thoughts... burned out or would it not work due to pressure? When there is vapor-lock does the fuel pump still still fire up when turning the key on or does it shut off for safety reasons?

Thanks,

-Kevin

[ScottS]

Hi Scott, as Ratchet mentions, cold water on a hot engine could cause metal warping or cracking in extreme cases. I've actually seen it happen with cast iron engines, never aluminium, but who knows. I must admit I did the same thing 3 yrs ago in the middle of nowhere [Midway, B.C.], totally pissed at the bike, didn't care if I cracked the engine, found a hose at a gas station, sprayed it up on the external pump & lines, fired right up.

The term 'burping' I used when I first started poking around with the bike on the side of the road one hot August afternoon with my buddies watching. A slotted screwdriver is enough to loosen the hose clamp coming off the bottom of the petcock. You may have to pull the line right off to release, but I just kind of spun the hose on the petcock orfice, that was enough to start releasing pressure, mostly atomized fuel [air] but there may be some liquid gasoline spit out as well, so be carefull where it lands if the engine is hot, if you know what I mean.

Check with Greg Field or Pete Roper on this forum, but I'm pretty sure that 1999, 2000. and 2001 V11's had the electric petcock, after that, manual petcocks were exclusively used. Why they went electric I'd like to know, it was stupid fucking idea. The manual petcock is quite inexpensive, I rode down from Vancouver to Moto International in Seattle one day to get one, Greg had them in stock. I'd get rid of the electric one for other reasons besides the vapour entrapement issue. The wires at the bottom of it are not very big, and vibration damage can cause the fuel delivery to stop, yet you'll never see the wire broken inside the isloator, exactly what happened to me, twice, both covered by warranty in the early 2000's. My local dealer, British Italian in Vancouver, would not upgrade [the manual one's actually cheaper] to the manual, so I had to play the game Moto Guzzi used to play during the Aprilia years.

 

Steve

 

Thanks for the great advice- yes I too was concernd about the water on a hot engine thing, so I let it cool down and then I used a fine mist , not a direct flow.

 

Teh dealer sugested (Joe) is wonderful and a petcock is on its way to me.

 

Wow I love this bike. What a hoot

 

Thanks again for the help.

 

Next on the list is valve adjustment and mixture/TPS stuff , I been reading lol /.

[ScottS]

You need to call Joe Eish in Salineville,Oh. 330-738-3944

 

Thank you , the guy is wonderful to deal with

[Guest ratchethack]

My '03 cut out the other week when sitting at a light in pretty hot weather. I rested in the shade awhile and it started up. As I took off down the road at 35 mph it once again cut out. From that point on I couldn't get the fuel pump to dance upon turning the key. I opened the tank twice, have never had vapor lock anyhow EVER, and no pressure. The fuses are all fine and the relays are new and are fine. They click when I turn the key on. Why is my pump not working? Any thoughts... burned out or would it not work due to pressure? When there is vapor-lock does the fuel pump still still fire up when turning the key on or does it shut off for safety reasons?

Thanks,

-Kevin

Kev, there's no reason for the fuel pump not to spin when vapor locked, but you can burn it out by spinning it too much "dry". You should hear it even when it's cavitating in vaporized fuel. You could test it by applying voltage directly. The 10A pompa fuse (#2 front-to-back) could have burned out and still look good (BTDT). I would suggest testing it for continuity and/or replacing it. Hearing a relay click is no guarantee that it's working properly. If you're able to rotate relays from one socket to the next (all 5-pin required), I would try this in an attempt to ID a bad relay. If a relay fault is discovered, after having tried all the usual suspect relays (Seimens, Bosch, Tyco, GEI), and finally going to the only ones that have NEVER given me trouble, I highly recommend Omron relays from Forum member John Mickowski.

 

Order here: http://www.motratech.com/Motratech/MGRC20.html

 

Hope this helps.

[Steve G.]

My '03 cut out the other week when sitting at a light in pretty hot weather. I rested in the shade awhile and it started up. As I took off down the road at 35 mph it once again cut out. From that point on I couldn't get the fuel pump to dance upon turning the key. I opened the tank twice, have never had vapor lock anyhow EVER, and no pressure. The fuses are all fine and the relays are new and are fine. They click when I turn the key on. Why is my pump not working? Any thoughts... burned out or would it not work due to pressure? When there is vapor-lock does the fuel pump still still fire up when turning the key on or does it shut off for safety reasons?

Thanks,

-Kevin

 

 

Your '03 model will, as far as I know, have an internal fuel tank fuel pump. It will also have the factory installed manual fuel pump. I would say with this in mind, that your bike is not suffering from the vapour lock issue the early models had. You may indeed have a failing fuel pump.

All the V11 series, indeed every fuel injection motorcycle made, will give off an audible sound as the pump brings the system up to operating pressure. If yours is not doing this EVERY TIME you turn the ignition key on, you have either an electric issue to the pump, or a mechanical issue with the pump itself.

 

Steve

[Steve G.]

Your '03 model will, as far as I know, have an internal fuel tank fuel pump. It will also have the factory installed manual fuel pump. I would say with this in mind, that your bike is not suffering from the vapour lock issue the early models had. You may indeed have a failing fuel pump.

All the V11 series, indeed every fuel injection motorcycle made, will give off an audible sound as the pump brings the system up to operating pressure. If yours is not doing this EVERY TIME you turn the ignition key on, you have either an electric issue to the pump, or a mechanical issue with the pump itself.

 

Steve

 

 

Sorry, I should have said manual fuel petcock, in the second sentence above. The '03 models had the superior manual fuel petcock.

Steve

[kevdog3019]

Thank you guys. I do have the Matra relays already and tried swapping them several times. I will try the 10amp fuse change even though it looks great. After this, I would suspect the pump is bad or something happened to the connection. Never had tank suck issues in 30K miles so that's no issue here. Another very strange occurance on this bike, as I just replaced the starter solenoid. Been perfect otherwise. Just wanted to rule out anything else maybe you knew about.

Thanks again.

-Kevin

[ScottS]

Well I am now convinced the "accumulated bubble" in the lines after many starts is the issue- I had the no start condition last week ( at 1 AM ) and the temps were very cool and the bike had been sitting at least an hour. I pulled the hose off the petcock n put it back on and she started right up. Maybe a T fitting with a schraeder valve would facilitate quick bleeding. I read of a re-routing of the lines to fix this and I will probably look at this this winter.

 

Just prior to this she had started to cough off idle and generally run ratty ( lean)

 

After the bleeding , ran super .

[justmike]

SOunds like a bad petcock or a venting issue. Do you still have the electric petcock? If so, replace it with a manual petcock. Leave the manual one open all the time unless removing the tank. While you are in there, re-route or shield hoses to reduce the tendency to vapor-lock.

 

I just had the same problem - went straight to the electric petcock and voila - both wires fell off in my hands! It's quite a simple job to solder them back on - the chrome cap on the bottom of the valve slides off, leaving plenty of access to the solder connections to the coil. Slid the cap back on, applied a little epoxy into the well around the wires and stuck the tank back on. Fired right up and runs great.

This forum just saved me hours of head-scratching - thanks for the help. My next step is to hit the donate button.....