vapor lock

[docc]

Gio,

 

Have you tried fitting a new petcock to be sure there is not intermittent electrical failure with it?

[Gio]

Thanks for the feedback everyone.

 

Re the injectors (dlaing) - I see what you mean - I forgot to take measurements - will include in my next expt.

 

Re the pump location (al) - perhaps using the bracket that was posted earlier in the thread..? (I would try a temporary mount first of course). Anyone have a picture of this set-up on a late '02 model?

 

Re the petcock (docc) - at least this would rule it out for sure. Just out of curiosity - do the folks with manual petcocks need to open/close each time or just leave them open?

 

Gio

[Gio]

Expt # 5 - Pump/Filter re-location

 

1. Re-located fuel pump above spine (where filter was)

2. Re-routed primary fuel supply from LHS underneath airbox (caution re intereference with TB linkage) and up to the pump from the RHS.

3. Re-located filter up-front (lots of space inside a Magni fairing!).

4. Heat-shielded both the primary line as far as and including the pump and also the filter/injector line from this same location back down (ie above the cylinders)

 

Otherwise same conditions as expt #4 (these values in brackets)

 

Ambient = 47F w light rain (50)

Cyl temp = 199 to 211F (203 to 207)

Supply line (as measured on the LHS) = 94F (132)

Pump = 94F (182)

Return line (RHS) = 82F (87)

 

And at t=15 mins

 

Cyl temp = 151 to 164F (170 to 177)

Supply line (as measured on the LHS) = 95F (121)

Pump = 97F (151)

Return line (RHS) = 91 (84)

 

So a significant reduction in both supply line and (in particular) pump temperature.

 

Drum roll please....

 

At t=48mins the motor started without incident!

 

I ran the motor (stationary) for 3 periods of a few mins each and re-checked temperatures (note - no air-cooling) :

 

Supply line (LHS) = 100F

Pump = 130F (max observed was ~150F)

 

Re-checked at t=120 mins - still no Vapour Lock.

 

In conclusion, it would appear that re-locating the supply line, pump and filter has had a beneficial effect on the "Vapour-lock" problem. It would be interesting to see what happens if the filter is re-located to where the pump used to be (might be preferable or necessary for those folks without any space up front).

 

I'll keep monitoring and update with any further observations.

 

Gio

 

(PS - dlaing - I didn't forget those injector measurements - typically 70 to 80F)

[al_roethlisberger]

Whoo-hoo.... so my more intuition and less scientific results of moving the pump above the spine seems to have been verified as having a positive effect

 

Thanks for the objective and very detailed testing Gio!

 

Awesome

 

al

[dlaing]

(PS - dlaing - I didn't forget those injector measurements - typically 70 to 80F)

Drat!

I was way off.

But the results are excellent, because if it got hot at the Throttle bodies, there is not much you could do.

My only concern with the results now is that the cylinder heads cooled off more durring the last tests, apparently due to weather.

But no vapor lock is great news.

Even for those of us who never vapor lock, a relocation may extend pump life.

[docc]

My Sport has never vapor locked . But I thought it good to take some simple precautions. Not to the extent Gio did but stilltrying to prevent trouble, I slid the fuel pump up in the bracket 15mm ( 5/8 ") and rotated the petcock to be sure the fuel line misses the head fins.

 

Does everyone have a rubber coated pump and steel braid over the fuel line?

[al_roethlisberger]

Yep, that's the stock configuration pre-2003(and some 2002's where they moved the pump out front ala Centauro/1100i).

 

My 2002 LeMans had the exact same setup as pictured.

 

al

[jtucker]

Gio (and all), thanks for the brilliant work on this. I suffered from the vapor lock problem as well, and will have to try the relocation mod for sure!

[Gio]

No worries - I hope you are able to overcome your VL problem.

 

Gio

 

PS - Still no VL since the last modifications..

[jagnut]

Maybe I'm the last one to find the solution to this problem but I didn't get it till yesterday and only then from a separate posting by Tom Halchuk of Boston on a different URL. Following is my note of thanks back to Tom:

 

Hi Tom in Boston,

 

YOU ARE A LIFESAVER!!!

 

I have been struggling with a vapor lock problem on my V11 Sport for the past 8 months. It has been getting progressively worse and driving me crazy. Yesterday I found your blurb "V11 Sport Won't Start - Electronic Fuel Tap". I checked my bike when I got home and lo and behold only one wire was actually connected - THE OTHER ONE WAS COMPLETELY DISCONNECTED. I don't know why it ran at all!

 

Today I called the Guzzi shop to order a new solenoid and bought the manual version - NO WIRES. I don't believe I'll have that problem again!

 

Thanks so much for taking the time to post your experience!

 

Hope I can help someone else with a similar problem.

[BrianG]

I have been trying to be proactive in this vapor-lock issue while there is still ssnow on the ground up here!

On reading every thread that I can find, I like the idea of moving the fuel pump onto the top of the frame. This leaves the issue of the fuel filter, because it's pretty large. Looking at the thread on replacing the whole fuel-tank with one with the fuel pump package inside, I noticed that the integral fuel filter is relatively tiny!

 

What might be the consideration in replacing the original large one with a smaller one (like the integral one), to avoid the relocation issue altogether by placing it immediately proximal to the fuel pump, on top of the frame??