vapor lock

[al_roethlisberger]

I have been using the AN-8 high-pressure/heat hose you can get at speed shops for fuel/oil/coolant lines. It's blue colored, nearly indestructable, and rated at 250PSI and something like 300 degrees I think... I think it's made by Aeroquip.

 

al

[Gio]

As posted earlier under the hole in air-box thread, I have recently twice experienced increased vapour-lock symptoms under much cooler (~15c) conditions than previously (~25c+) after removal of air-box snorkel arms and drilling the lid.

 

I'm running a K&N filter and PC with 706.002 map (mistral/stock x-over).

 

On both recent occaisions, I took the bike for a short ride, stopped for approx 20 mins and then re-started without incident. Upon stopping for a second time the bike went into classic cough/splutter/back-fire and die mode. I tried allowing to cool (approx 20 to 30 mins) but in the end pushed to nearest gas station and sprayed cold water over the primary fuel line and pump followed by compressed air for an evapourative cooling effect. Started no problem after this treatment on both occaisions.

 

Unless I've missed a revelation over the last few months, my understanding is that the best guess on the cause remains heat-soak into primary fuel-line and or fuel pump. The above observations support this.

 

My plan of attack is to 1) re-locate the fuel pump (still searching for a source of 7/16 hose) 2) insulate with Thermo-shield/sleeve (ready to go) and 3) if necessary add a cooling fan.

 

Any updates or suggestions are most welcome as not riding is not an option for me.

 

Gio

[Gio]

Al,

 

I did a search on Aeroquip and came up with this link :

 

http://www.bakerprecision.com/earls22.htm

 

1) Does the FBV0800 (0.5'' id / 0.75" od) look like what you were referring to as AN-8 in your previous post?

 

2) I assume you used this just on the 7/16" primary (tank to pump) line?

 

Gio

[al_roethlisberger]

Yep, that's it -8 A(rmy)N(avy) hose FBV0800

 

...and yep, I only replaced the "big" supply hose(s)... plural in my case due to my mods

 

al

[Gio]

Thanks - I'll order some today.

 

Gio

[Janusz]

I believe that all that would be just fighting symptoms but not the disease and would just obscure the real reson of vapour lock.

 

After all my bike, for instance, has no airbox lid (Ferraci bracket) and will not go into vapour lock even in 30*C plus. That proves that the design is not wrong and things like extra fans etc. are truly not the solution.

 

I've had only one vapour lock experience before and after bumping up all the lean spots with PC the engine runs perfectly.

[Gio]

Hi Janusz,

 

I fully agree with your logic - and would welcome the opportunity to try (or at least compare) your map with the one I'm running to see if I get the same benefit as you seem to have done. This would be most usefull prior to any further changes on my part I think (Forum folks - is there a place that we can post PC maps on the site for this?). I would also agree that a fan should be the last resort.

 

But, my reasons for wanting to go ahead with the fuel supply mods also include the following :

 

1) There seems to be a wide range of susceptibility to the problem (ie owners have experienced vapour-lock to different extents, or even not at all)

 

2) Based on the crap that came out last time I changed the filter, new lines would not be a bad idea as these could well be the source of the particulates

 

3) Even if the location of the fuel-pump proves not to be the main problem, I figure it would rather spend the rest of its days in a cooler climate than stock.

 

Thanks again for the feedback,

 

Gio

[biesel]

Could this help cooling the fuel pump?

 

 

Sport Cycle Pacific

[Gio]

Looks like a nice bracket but I think that this would only help cool the pump once it becomes hot - in this case a better strategy might be to prevent it becoming hot in the first place (ie reflective heat shielding)...? All of which assumes the source of the heat is from the engine

 

Having said that, if the pump was mounted out front as on some models, this would certainly look better than stock.

 

Gio

[al_roethlisberger]

.... I guess I need to put that clamp in the FAQ section as well (...see past vapor lock threads )

 

First, after speaking to the guy that makes it, he's not 100% sure it will fit the new models .... although it should as I believe the pumps to be the same for all the FI Guzzis.

 

But more importantly, "finned" heat-sinks are passive, so they go for entropy... that is, they will absorb or radiate heat as necessary to balance the temperatures of what fluid/solid they are in contact with. Good heat conductors like aluminum and copper are often used.

 

Since our problem is with "heat soak" versus the pump overheating internally, all this fantastic heat-sink/conductor is going to do is heat the pump up faster as the ambient temperature outside the pump is the problem, and this clamp will conduct that heat and surround the pump with it ever more efficiently.... to the owner's dismay

 

Now, if the pump were itself overheating, and the ambient temp outside the pump were cooler(like our cylinders), then yes this clamp might help radiate that heat away.

 

The only potential benefit this clamp might have is to potentially cool the pump after the heat-soak cycle has reached it's maximum, and the engine/air starts to cool. If the pump cools at a slower rate, this might radiate the heat back out a little faster, improving recovery time. But I doubt this would happen, as I think most of the heat energy and problem is in the low-pressure side of the fuel system.

 

So IMHO, heat shielding the supply line, and maybe the pump are better choices.

 

 

That being said, I might buy one of these clamps just to have a cleaner mount for my relocated pump, but it'll be heat-shielded

 

al

[Gio]

I found the following map at www.guzzitech.com (thanks to both Tom H and the Guzzitech site for making this available) :

 

V11-TomH.map (K&N filter, top of airbox removed, Mistral ovals, stock x-over)

 

This closely matches my congfiguration (K&N, drilled airbox with snorkels removed, Mistral round, stock x-over) and in comparing with the map I'm running (706.002) note significant richening (particularly at low and mid throttle) which should result in a cooler running engine.

 

Before re-locating the fuel pump with the new hose (which has now arrived), and unless anyone has a more appropriate suggestion map-wise, I plan to load this map and see if it has any beneficial effect on the "vapour lock" syndrome...?

 

Later,

 

Gio

[Gio]

As promised - here are some preliminary results of the vapour-lock expts. I used an infra-red thermometer to measure various places (cylinders, supply and return fuel-lines,fuel pump etc) using the two different maps following a test run of ~ 40km, calling this t=0 mins :

 

M706.002 map (what I was running prior to airboxtomy)

 

Ambient temp = 40F

Cylinder temp at end of run = 235 - 237F

Supply fuel line (LHS) = 130F

Fuel pump = 173F

Return fuel line (RHS) = 88F

 

V11TomH map (much richer map - feels good)

 

Ambient temp = 48F

Cylinder temp at end of run = 213 - 216F

Supply fuel line (LHS) = 116F

Fuel pump = 157F

Return fuel line (RHS) = 87F

 

So my initial conclusion is that the richer map reduces peak cylinder temperature (by approx 21 + 8 ambient = 29F) as expected.

 

However, despite this, after 15 mins, the temperature of both the supply fuel line (118 and 123F respectively) and fuel pump (134 and 130F respectively) were similar. I have data points every 5 mins and have plotted the cooling curves for each location (I guess I could post the graphs - not quite sure how to do this..)

 

So the main conclusion from this experiment was that although a richer map reduced engine temperature as expected, the main fuel line and pump were heated to similar extents. Vapour-lock was present in both cases ( engine would not start at t=48 mins after end of each test run.

 

So my next experiment will be to heat-shield the main fuel-line and fuel pump.

 

Gio

[callison]

Wouldn't it be funky if the problem was actually the electric petcock screwing up from engine heat? Mine just died, so I've substituted a manual type from a Sport 1100i. I never had the vapor lock problem though, so I'll never know if this is a cure or not. Maybe someone that has switched to the manual petcock that has had the vapor lock problem can check if the problem has ever arisen after the petcock switchover. FWIW, the electric petcock is poorly located and damn fragile.

[dlaing]

Gio, Excellent Work!!!

I hope the shielding can lower the temperature enough.

It is odd that some fail and some do not.

Despite climates, etc.

[callison]

Hi my name is Reinhold Probst, I own Euro Cycles, a Moto Guzzi Dealership in Tampa Bay Florida.

One of the issues I believe contributing to this is the fact that the fuel pump times out after a few second when the motor is not actually running.

Regards,

 

Reinhold

 

Uh huh. Light bulb flares over my tiny brain. I always wondered what connector #57 (V11 Sport Wiring Diagram) was for. This is the trouble shooting bypass for testing. Since the ECU times out if not running, you can't check voltages at injectors etc. without a bypass - and this is it. However, since most of us (except Al, the fiend) don't have an AMP connector set, the easiest thing to do is to pull the ECU relay (#49) and use a jumper or clip leads to connect terminals 30 and 87 together. This will make the injector, coils and pump circuit live when the ignition is on. This can make for an interesting mess if the gas tank is off as the pump is going to run when you bypass the relay and turn on the ignition. Unlike the Sport 1100i, which has a connector to easily disconnect the pump, the V11 Sport has to have the pump disconnected at the terminal. Lest you desire the smell of fuel or the rapid acceleration outward and possibly upwards from your work locale as the fuel ignites, you should probably disconnect the fuel pump before checking these circuits.

 

Now that I know this, I can continue work on the Sport 1100i to get it running.