Relocating Fuel Pump

[al_roethlisberger]

 

But the question still bothers me is why does this problem seem regular for some and then non-exsistant for others?

 

 

 

...and indeed, that is a good question for sure One unfortunately I don't have the answer to as I don't have personal access to a large enough sample of those affected and their circumstances

 

My "VL" was very rare(only happened once, in 100+ degree high-altitude Yosemite weather - about the worst-case scenario)... until of course now the other day and the report I gave above. I have no idea why with some others it seems to be more regular, other than perhaps their fuel-supply line was *very* close to the head... dunno

 

But as pointed out earlier in this thread, and perhaps as a consideration toward your question.... we have seen no less than 3 different(maybe more?) fuel-pump locations on the V11 Sport/LeMans from 2000->2002(post-2002 have in-tank systems).... so with all these variables thrown into the mix along with different climates.... it's a crap-shoot to nail-down the exact cause from one person's incident/perspective *sigh*

 

It's too bad MG never did address this other than surreptitiously moving the pump around multiple times, and eventually redesigning the pump/tank in 2003... so it's up to the owners that have the issue(I ride in high-desert, so can't risk this) to find a solution I guess <_>

 

al

[al_roethlisberger]

Well,

 

The story get's more interesting as I test and research more and more into this

 

 

At first I was really frustrated with this whole affair, but I think I now know what's going on, although I have to admit it's still a bit frustrating as even understanding the problem doesn't allow me to ultimately do what I want.... yet

 

 

 

 

So, keep in mind that this is tied closely to the Forum Vapor Lock Thread

 

 

Let's recap.

 

First, or "Phase I" ... to reduce the chance of heat induced vapor lock, I relocated the fuel pump up on top of the spine in-line with the fuel-filter, along with heat-shielding the whole system. This was successful, and I went on several near-100 degree F rides with no problem. If this had been my only goal, I could have stopped here.

 

 

With that success in my hip-pocket, I moved to the next "phase" which was to enable a "balance tube" between both sides of the tank to allow more even access to the right side where quite a bit of fuel is trapped as the fuel level drops. This is the side from which the fuel-pressure regulator hangs.

 

Upon setting up this solution using a newly fitted second petcock, and remotely locating an external pressure-regulator(detailed earlier in the thread), a ride in 80-ish degree weather induced vapor lock .... DRAT!

 

This was very surprising, and I thought that perhaps my location for the regulator above the right cylinder was the culprit(although I suspected a secondary possibility.. more on that next ).

 

Well, over the last day I relocated the pressure regulator somewhere extremely remote to the whole engine.... But as I ran the engine up to temp, and felt the regulator housing, I noticed that it was quite warm. And soon enough, yep... vaporized fuel! cough cough... dead. DOUBLE DRAT!!

 

At this point, my secondary theory... yet unmentioned... seemed more likely *sigh*

 

 

 

I hate to leave you in suspense.... but....

 

 

So in the meantime, I've been reading online and researching various products used by hot-rodders and racers to combat vapor lock. It usually consists of "coolers" which are of course just small radiators, and cooling bottles/jugs, which are liquid filled containers with a submerged radiator. But bottom line, there is some facility for the fuel to get cooled before reentering the pressurized circuit.

 

My "balance tube" solution couldn't allow for this, as we are limited to two fuel inlet/outlets on the tank.

 

So what I had worried about from the start, but only in the back of my mind, and now seemed to have come to fruition... is that by not having the fuel cycle all the way back to the tank via my modification, a significant proportion of the already warm fuel was recirculating around and around, just getting hotter and hotter... instead of squirting up into the fuel tank, mixing with cooler fuel before getting sucked/pumped back into the system.

 

This is the curse of only having two taps into the tank I guess

 

 

So, I'm going to replumb the circuit tonight so that the fuel can go back into the tank to confirm this suspicion. If the bike runs fine back in that configuration, it should support my conclusion.

 

 

So, what does this mean in regard to making a "balance tube" ?? I don't know for sure I suppose one could still potentially pierce the tank and add two new fittings and a tube, but I wouldn't feel confident about that with the nylon? tank. Long term reliability would make me nervous. Fuel leaks are baaaad <_>

 

 

But here are two possibilites for a new/third tank access for a fuel return??

 

1) Ditch the fuel-level indicator/sensor and use that as a fuel return:

 

One could certainly do this, but the obvious tradeoff is loss of the low-fuel indicator, plus who knows if one could even match a fitting to the outlet

 

2) Use the tank overflow nipple under the tank on the right:

 

OK, I have no idea on this one. Perhaps impossible?? I'd have to look into whether the overflow actually drains right back into the tank directly, or via the cap. If it is via the cap, this would probably be a bad idea = fumes, splash, etc. I'm also not sure if it could even flow enough fuel.

 

 

So, any thoughts? If not, I'll probably just put the the system back to "Phase I", put the pressure-regulator return back into the right hand side of the tank, and give up on a balance tube for now

 

Too bad if so....

 

al

[docc]

From what you've found , and some of Gio's work, it sounds like the lines themselves are highly susceptible to heat soak. Isn't there an unshielded fuel line between the injectors that lies pinched between the frame and gearbox?

 

I recall some braided fabric sleeves used in racing applications wehich may be appropriate. I'll see if I can find a source from records I have on the Merkur (Sierra) I refitted.

 

Secondly, every time I have the tank off I find some of the reflective heat shield needs reattaching. I've been using "Shoe Goo", a toluene based adhesive. I wonder if the tank itself is susceptible to 'hot spots' that would benefit from a little extra shielding.

 

Finally, that pressure regulator is completely unshielded. And the line to it is rather loosely draped. I don't remember if Gio took heat readings on that side.

 

( You asked for some thoughts)

[Gio]

Hi docc,

 

I just checked my notes and in answer to your question I was measuring between 80 and 90F on what I call the RHS fuel line (return line) regardless of VL or not...?

(eg expt #4, 84F at t=15 mins w VL followed by expt#5, 91F at t=15mins no VL)

 

Al,

 

I'm also thinking that a fuel cooler would only be of benefit whilst the fuel is moving - if we are indeed victims of heat-soaking, then unless the cooler was located at the "hot-spot", this would still occur once fuel flow stops...? One thing does seem consistent with VL - if you can start and keep running for a few minutes, you are usually ok (presumably due to the displacement of heated fuel?)

 

Gio

[al_roethlisberger]

I agree on both the points made above:

 

1) A "cooler" wouldn't really help unless it was optimally placed in the air-flow, and/or with active cooling, such as with a fan. And I believe we can "lick this" without that anyway

 

2) The lines are indeed part, maybe a large part, of the problem. This is clearly evidenced from my test above where recirculating fuel just got warmer and warmer. I've had my lines relocated further from the heat, and shielded for some time. And before my mod that made the situation worse, this seemed to work. The aluminized shielding reflects 95% of radiant heat, but of course can only do so much for temporal heat soak

 

But I think I've got the problem licked.... well maybe. More testing is needed.

 

See the following thread:

 

Wasted Fuel Thread

 

I'll keep you posted

 

al

[al_roethlisberger]

Latest plumbing

 

... much of which is detailed in the Wasted Fuel thread mentioned above. If I can get the vapor lock issue knocked out with this setup, all future updates will be in that thread, as it's more appropriate since I am now focused on "Phase II" which is getting to that fuel isolated on the right side of the tank <_>

[al_roethlisberger]

Location of the relocated remote fuel-pressure regulator. It is mounted to my fabricated undertail fender, and was the most convenient location to get it away from heat, and where there was sufficient room.

 

A little more info in the Wasted Fuel Thread .

[al_roethlisberger]

Well, I guess the final note to this thread is that it does appear that my final modification, and suspicions about the recirculating fuel issue were effective and correct.

 

I think that although complicated, and perhaps silly looking to some, the two "phases" of this modification did meet their goals:

 

1) Relocate and shield fuel-pump/filter/lines to reduce/eliminate vapor-lock

 

2) Make all the fuel contained in the tank available to the fuel-injection system

 

 

I rode the bike for the last couple days in "hot" weather(80s), and so far have been lucky enough not to have it vapor-lock on me, even after some rather extreme and purposeful heat-soaks.

 

 

So, unless there is a major problem or other observation, I guess I can close this thread now. As mentioned above, any further updates will be in the "wasted fuel" thread.

 

Further, if the 2003 tank with the internal fuel-pump has similar capacity, range, and works out well retrofitted to my 2002 LeMans, this solution will be retired anyway for the sake of simplicity.

 

But I hope that it provides some inspiration and guidance for those that want or need to try these modifications.

 

al

[Guest Brian Robson]

On behalf of everyone who has enjoyed your mechanical windmill tilting; Thank you Al for a great thread and a great deal of work.

I do find it troubling that anyone would have a fuel system so sexy looking, but even more troubling is that I find it so.

Lets hope that when you finally get to ride, that all the mods give you a great time

[al_roethlisberger]

Thanks Brian

 

...but to some degree, not so much "tilting" as the bike didn't like to run when the temps were over much over 95 <_>

 

It seems to run now, at least so far

 

al