Ultima Fuel Delivery System Flaw?

Ultima Fuel Delivery System Flaw?

Author
Discussion

skidiiii

Original Poster:

57 posts

148 months

Sunday 20th April 2014
quotequote all
Hello all,
After 2 years of driving the GTR the biggest beef I have with it is the fuel delivery system. I was having intermittent starvation problems that led to what I thought was a faulty fuel switch. (LS7 A/S engine) Finally the left side would no longer empty at all. I ordered a new fuel switch from Ultima and was dreading swapping it as it is a bugger to get to after the engine is installed. It took about two and a half hours to remove the fuel switch box and get it out of the car. The tricky part was emptying the full L/H tank as it would not switch over. I opted to have 2 5 gallon gas cans at the ready and pulled one of the lower tank lines free of the switch and gravity bled the tank. Much to my surprise out of the line was several inches worth of the bladder material from inside the tank. (looks like a Brillo pad) As I dissembled the R/H lines it also had baffle material partially obstructing the supply line. It was obvious why the switch had failed and the fuel starvation was occurring. I feel this design is way too complicated and have been thinking about a simpler option that would have the filters placed before any critical components and not after. I am not a fuel expert so please feel free to chime in with thoughts or similar experience. I have attached my design idea that could be used to run both pumps at once or as Ultima has it one or the other. Any thoughts on the design would be greatly appreciated as I plan to do it next week some time. Pix also attached of the clogged fuel switch.

skidiiii

Original Poster:

57 posts

148 months

Sunday 20th April 2014
quotequote all
Sorry pix didn't attach of fuel switch, here they are.[url]|http://thumbsnap.com/KdOsoxdi
[/url][url]|http://thumbsnap.com/POfyO40u
[/url]

Storer

5,024 posts

214 months

Sunday 20th April 2014
quotequote all
Hi Roe

You will find the fuel system has been discussed many times and there are nearly as many different ways of achieving the desired result.

A lot depends on how much work/time you want to spend. The simplest solution may be to fit a coarse filter on the tank side of the low pressure pump. If it blocks again you may end up with fuel starvation issues again though.

Some of us have redesigned the system completely. I have linked both tanks with twin hoses at the bottom and fitted an in-tank pump down one of the fuel level gauge pipes with a coarse filter on the bottom. This feeds the swirl pot via a fine filter. The high pressure pump is immediately after the swirl pot and feed straight to the fuel rail. The regulator is after the rail.

The regulator feeds back to the swirl pot and then the pot vents back to the tank with a small restriction to create a small amount of pressure in the pot.

I can monitor fuel pressure inside the car and have never had a problem since fitting this setup.

Paul


skidiiii

Original Poster:

57 posts

148 months

Sunday 20th April 2014
quotequote all
Thanks Paul. Do you have any diagrams or pix of your system. I think I understand the concept. If I had both pumps running would I need a swirl pot? My theory is if both tanks are feeding together under pressure no fuel starvation could happen even in the event of heavy cornering.

F.C.

3,896 posts

207 months

Sunday 20th April 2014
quotequote all
Get rid of the pollack valve.
Join the tanks at the bottom.
Tee the returns to the tanks.
Feed main pump via swirl pot, this will prevent cavitation regardless of tank levels and cornering G.

Storer

5,024 posts

214 months

Sunday 20th April 2014
quotequote all
If you join the tanks at the bottom you should not need to return via a 'T' to both tanks as they will self level. Best to return to the one you pull from if only pulling from one though.

Paul

Justaredbadge

37,068 posts

187 months

Sunday 20th April 2014
quotequote all
Wouldn't a coarse filter before the valve block sort this?

skidiiii

Original Poster:

57 posts

148 months

Sunday 20th April 2014
quotequote all
Was that in the coloring book?

Storer

5,024 posts

214 months

Sunday 20th April 2014
quotequote all
I wouldn't know how to do a diagram on here so a description is all I can offer. I can do a pic or two but they do not show flow.

Two pipes linking bottom of both tanks.

Fuel pumped from inside the l/h tank (sat in the seat or your driver side) using a Aeromotive submersible pump fitted (tightly) into the fuel level sender pipe.

LP pump feeds into the swirl pot (I lied earlier due to wine) all mounted above the l/h tank.

From swirl pot to A1000 h/p pump and then through the fine filter (coarse one on l/p/pump).

From filter to fuel rail (side of engine).

From fuel rail (at pulley end after removing 'valve') to regulator.

From regulator back to swirl pot (2/3 way up pot).

From swirl pot top through restrictor to l/h tank.

Job done.

Fuel pressure sensor is in the regulator.





Hope this helps.


Paul

skidiiii

Original Poster:

57 posts

148 months

Sunday 20th April 2014
quotequote all
Thanks Paul, nice set up! I like how simplified this set up is.

spatz

1,783 posts

185 months

Monday 21st April 2014
quotequote all
both systems work in my cars

newer system which I recommend



I should mention that in reality I have installed a T in the 6 top link which ends in a self closing
fuel valve. The Ultima filler cap is possible to be adjusted so it will be fuel tight, so if
the car tips over the valve will close and no fuel will be spilled.

skidiiii

Original Poster:

57 posts

148 months

Monday 21st April 2014
quotequote all
Spatz,
Thanks for the diagrams. In the lower one did you seal off both over flows essentially creating a non vented system. Then you added a T on the top side tank with a self closing fuel switch thus venting the system at this point. What type of switch is available to sense fuel and disable the fuel pumps in the event of a roll over? The fuel rail supplied from AS has one -6 fitting and a Schroeder valve at the rear. Would I have to source another fuel rail as well then? It looks like you would want both to be -6 fittings? Thanks again for the post!

skidiiii

Original Poster:

57 posts

148 months

Monday 21st April 2014
quotequote all
Also noted the -12 fittings in the second diagram. Mine has -6 all around. Will this still work ok if I do the lower diagram?

skidiiii

Original Poster:

57 posts

148 months

Monday 21st April 2014
quotequote all
See changes made to the lower diagram for reference. Think this will work ok?

ROWDYRENAULT

1,270 posts

213 months

Monday 21st April 2014
quotequote all
You asked for input so here goes. First of all I am opposed to these over complex fuel systems but in spite of that: 1. why would you return hot fuel off of the rail back into the surge tank? Why not back to the tank where it might get a chance to cool. 2. A number 6 line as an interconnect between the tanks is to small I would suggest at least a 1 inch line. I have such a line on mine and you can fill the car from either side as quickly as a normal car. hope that helps. Lee

anonymous-user

53 months

Monday 21st April 2014
quotequote all
ROWDYRENAULT said:
You asked for input so here goes. First of all I am opposed to these over complex fuel systems but in spite of that: 1. why would you return hot fuel off of the rail back into the surge tank? Why not back to the tank where it might get a chance to cool. 2. A number 6 line as an interconnect between the tanks is to small I would suggest at least a 1 inch line. I have such a line on mine and you can fill the car from either side as quickly as a normal car. hope that helps. Lee
Returning rail spill back to the swirl pot means your lift pump only has to "keep up" with the fuel consumption of the engine, and not the bulk flow of the high pressure system (which is very very much larger for most operating points. There is no "overheating" of the swirl pot for two reasons: 1) generally, heat is lost as the fuel travels from the rail through the pipework to the swirl pot, which also can radiate heat, and (more importantly) 2) the lift pump "dilutes" the contents of the swirl pot as it is running in parallel.

One of the best options if you want quick filling but no sloshing is to make your upper link pipe the "big" one (during filling, tank on filler side fills up first, and when full, the large upper cross pipe then quickly fills the second tank) and the lower one the "small" one (so hardly any bulk fuel slosh can occur between the tanks (this lower line only needs to act to "average" the contents of the tanks during running, and the fastest you can empty your tanks is really quite slow))

skidiiii

Original Poster:

57 posts

148 months

Tuesday 22nd April 2014
quotequote all
Great Post Max,
I wish I had the insight to have larger top links installed during the tank construction. If I had to do it again there are many things I would change. Wondering if I linked one lower set of -6 together and link 2nd lower set with an offset T closer to the tank I want to draw from would work. This would almost be the same as a -12 interconnect at the bottom of the tank. Fuel would not slosh as it would have to go through two smaller lines? Other option would be to lose the fuel sender in the tank being drawn from and insert a submersible fuel pump as suggested above. This would leave the the 2 lower -6 links uninterrupted. Thoughts anyone?

ROWDYRENAULT

1,270 posts

213 months

Tuesday 22nd April 2014
quotequote all
like I said Max Im not a fan of all this 18 pumps ect ect to start with, but slosh? what slosh? Through a 1 inch line your going to get slosh? not hardly by the way the blackhawk helicopter I used to fly had a single 2.5 inch connector between the two 180 gallon cells and slosh was not a problem even flying in extremely aggressive profiles dropping water on fires with a fixed tank. The only thing I will say beyond that is two tanks connected with a 1 inch line one high pressure Aeromotive pump mounted slightly lower than the tank, one filter, one fuel pressure regulator and the extra fuel off the regulator is sent to the tank opposite of the tank that has the pump. One fuel level sensor. 6 years, 20,000 miles, a few track days but not as many as I should, one run to 195mph on a runway, 118 degrees f down to 35 degrees F NO PROBLEMS

spatz

1,783 posts

185 months

Tuesday 22nd April 2014
quotequote all
skidiiii said:
See changes made to the lower diagram for reference. Think this will work ok?
yes this is what was missing in the diagram, this is how I actually built the system. The self closing valve is at the highest
point of the system.
The -6 link at the bottom will just make your gas filling slowere, but if you still have both fillers active then it is not really a problem just fill one tank after the other.

AlexCim

156 posts

153 months

Tuesday 22nd April 2014
quotequote all
Garhh. Your symptoms are exactly the same as mine. I only have a right tank at the moment. Dreading to remove it all, but I am definitely going to re-address the system when I am fixing it. Need to take the engine out anyway.

Thanks everyone for the input, I am going to take your designs on board when designing mine. Pretty annoyed this has happened though, I would have thought the factory fuel system would have it's bugs worked out.