Relocating Fuel Pump

[al_roethlisberger]

Final version, less hoses, more fittings

 

The "bridge" under the fuel-pump is made of two AN "tees" joined. Fuel is supplied by two OEM petcocks feeding two -6AN fittings, and a remote Weber(same manufacturer as OEM) remote pressure-regulator is connected to the now "H" shaped fuel manifold via -8AN fittings and hose to reduce fuel velocity as it exits the regulator. Ultimatley I would have preferred an equal flow "Y" connector from the regulator, as the current setup will still favor sending fuel to the right side a bit, but with head pressure from the tank, the decreased flow by using the -8 cross-section, and with "suction" from the pump, I'm hoping that my goals will still be reached.

 

Gio's testing has shown great results lowering heat, and apparently quashing the "vapor lock" scenario after relocating and shielding the pump in this thread:

 

Forum Vapor Lock Thread - see page 5 for Gio's results

 

 

Regarding "balancing" the fuel level in the tank, I consider this a "bonus" benefit, and only a few tank fulls will tell the tale. I'll report as I learn more.

 

 

View from above, shielding will also be installed on supply lines and fittings when complete:

[al_roethlisberger]

Closer overhead:

[al_roethlisberger]

Right side, note new external regulator and location:

[al_roethlisberger]

Left side, the "tee" on the back of the pump allows for some flexibility in the future such as a fuel-cell, or if I need to tune the setup a bit:

[al_roethlisberger]

HAHAHAHAHA... guess what?! I made the vapor-lock problem WORSE

 

Figures

 

 

I've been riding the bike with this setup for the last month in sub 50 degree temps, and all has been fine. But I was going to take the bike up for a dyno run and PCIII map, since last Thursday was so nice and WARM... HA!

 

Well, as soon as the temp got above about 65 degrees F, there she went!

 

But just let it cool for about 20 minutes, and I'm off again for a few miles, then... cough cough, dead.

 

 

Fortunately it's not a big deal, and not completely unexpected. I'm pretty sure I know the culprit.

 

Since I had the basic setup of relocated fuel-pump and modified plumbing(my "Phase I" ) in place since last Summer, and it worked fine in high-heat... the problem has to be something "new" I've done. And in this case, that's the relocated fuel pressure regulator.

 

And since I've been riding the bike with no other performance issues with this setup in colder weather(and my aforementioned experience Thursday), it's obviously thermal.

 

So, that pretty much means that my initial suspicion that the new location for the regulator, it being a big chunk of very heat-conductinvealuminum , isn't ideal. So I'll just find a new location and add some more heat protection after my holiday.

 

...funny how experimentation goes

 

al

[Gio]

Al,

 

This is a bizzare co-incidence. I had been riding without any VL problems since re-locating the fuel pump and filter - untill last Friday.

 

It was unusually warm and sunny day (~15c) and I took the opportunity to go for an extended ride at speeds appropriate to the road conditions.

 

After parking in an underground car-park for aprrox 30 minutes, I returned to experience my old friend Vapour-Lock on exiting, resulting in stalling and the need to park up outside for ~30 mins whilst things cooled off in the breeze outside.

 

I thought I had seen the last of this problem, but apparently not. I still think it has a thermal cause and will report the results of further investigation.

 

Gio

 

PS - happy VaLentines day...

[emry]

Al,

 

Are you sure you didn't swipe those photos from NASA?

[jrt]

He has it well thought-out....with 2pi^2 over the divisor of the circumfrence of the tube diameter and the inverse of the pump pressure taken below the cube root of the dangling participle equals..

[emry]

Quick question, have any one of you with the vapor lock problem tried bleeding the fuel system. Here are my thoughts...

 

Vapor lock is when the fuel in the line heats up to a point that the liquid fuel is forced in to a gaseous state. Much like an air bubble. When this bubble enters the fuel pump or is created there the pump looses its ability to pressurize the fuel. Someone correct me if I am wrong but our fuel pumps should be a rotary vane style pump. These pumps use the suface tension of a liquid (fuel) to create a seal between the rotor vanes and the pump housing. When an air bubble is present of large enough size the vanes no longer seal with the housing and the pump rotor mearly spins. At this point the pump no longer can produce adequate fuel pressure.

 

During a period of vapor lock has anyone loosened one of the fuel lines and allowed gravity to re-prime the pump? Loosening the line that is attached to the regulator should allow fuel to gravity feed though the whole fuel system at which point the fuel pump should work normally.

 

Or has anyone ridden with a fuel pressure gauge attached and noticed a marked decrease or increase in fuel pressure during the problem.

 

Also does this problem only occur to those of you with electronic petcocks?

[Gio]

Hi emry,

 

Good points - it would be interesting to monitor fuel pressure (if one had a gauge...)

 

I confirm that the stock electric petcock is fitted to my '00 V11S (but plan to replace this with a manual one)...

 

Gio

[emry]

it would be interesting to monitor fuel pressure (if one had a gauge...)

 

You can make one if you are daring or inventive. A $1 dial type tire pressure gauge and some fuel line works pretty good if you seal the connections real good. You just have to keep a close eye on the gauge in case of leaks. I made one about 5years ago and it still works pretty good, for testing at least, I wouldn't want to use it for extended periods of time.

[Guest dkgross]

Al, I am SO not letting you anywhere near my bike.

 

 

but, I might have to ride yours....

[al_roethlisberger]

Good thoughts Emry, but so far this has been a transient issue that once cooled off runs just fine again once the bubble "condenses". Once that happens, the pump reprimes and pressurizes just fine, and the bike will run again until it heat-soaks again

 

It definitely loses pressure once the VL issue arises, but once the bike cools, it pressurizes just fine.... otherwise it indeed wouldn't run without something like "priming" But so far, to run again, only time and cooling seems to be required.

 

In my case, I'm 99% positive it's my new relatively unprotected location(the ends aren't shielded) of the external fuel-pressure regulator..

 

My thoughts in this regard are:

 

1) It ran fine before in much hotter(90 degree) weather with the same setup, with no VL, except for the regulator relocation

 

2) It ran fine last week up and down the mountain in 50 degree weather, with this exact setup

 

 

So for me, this is actually "reassuring" because it narrows the possible causes a bit

 

When I am back home from Washington, I'll tinker with it and try to find a new location for the regulator

 

al

[al_roethlisberger]

Al, I am SO not letting you anywhere near my bike.

 

 

but, I might have to ride yours....

 

 

.....

[emry]

Well Al, lets hope this next relocation will sort the issue. But the question still bothers me is why does this problem seem regular for some and then non-exsistant for others? Components are located is very similar positions on the affected years, one bike has it one bike doesn't. That just does not make sense.

 

The part are or should be high quility, the regulator and the fuel pump are both out-sourced so that should rule out an quality build issue. It just doesn't add up.