[urq] UrQ Fuel delivery fix challenge!

[qshipq at aol.com]

 Ben
I never knock solutions that work!  I don't agree that the mounting of the anti-cavitation tank *needs* to be pre-pump in the urq.  That would only be the case if the fuel demand was a constant.  Can cavitation manifest itself at a bad time?  Sure.  And I applaud you for finding a solution with the noted challenge restrictions you self-imposed.  I don't see the solution to such a fueling issues as a 200$ fix.  Not for my own cars, or anyone elses.  Again, I'm glad you solved the problem, and did it with the constraints you put on your own view of it.  That's just cool Ben.  That's also not my view, nor the point of Peter's post.  I think we are both pointing out this isn't a new concept, and has been addressed the same, and differently, for many years.  If it solved the problem for you, that's all you need.  

Cheers

Scott J


 

 

-----Original Message-----
From: Ben Swann <benswann at verizon.net>
To: qshipq at aol.com
Cc: urq at audifans.com; 'Quattro List' <quattro at audifans.com>
Sent: Mon, Mar 29, 2010 12:10 pm
Subject: UrQ Fuel delivery fix challenge!


Scott,
WRT the conversion of the UrQuattro to an EFI system which has reduced fuel pressure and greater flow, I'll issue a challenge, since folks seem to be pooh poohing my solution I did over two years ago as not being optimal.
Regarding your comment regarding cavitation, space and mounting location is the main concern on the Ur Quattro.  Once the fuel is fed either by gravity or low pressure pump into a reservior with a large feed pipe, then cavitation becomes virtually a non issue.  Having the return flow teed into the surge tank pretty much eliminates negative pressure in the tank and sometime the fuel flow could reverse back into the main tank - great for keeping that sock clear of debris.
I studied many variations on surge tanks, fuel cells, race delivery systems, anti-slosh systems.  Many were simply a large tank in the trunk with a small fuel cell in the engine bay.  Many of these systems were applicable to dead head or low return flow applications - like carburators mounted in Drag Race cars.
In this case, the surge tank needs to come before the pump.  I considered using a low pressure carburator pump to draw fuel from the tank and pump into a surge tank, and I' tested it and it would have worked fine except for drawback of space and more complex wiring and plumbing.  Everything else was more expensive, too labor intensive, too much turnaround time, or space constrained and/or combination of the above.
Simplicity prevailed in the end - nothing fancy and works great.  So maybe there is a better more effective way to solve the problem than what I came up with.
The challenge, if anyone wants to go through the mental exercise and figure through all the caveats, is to have a fix to a constrictive fuel pump feed of 3/8" diameter with a slight kink from a tank that has a separate chamber at the bottom.  This feed essentiall starves pumps especially when the fuel pressure is dropped for EFI.  
The UrQ tank has a separate cavity at the bottom underneath another main bottom - so it is not a simple tank with one bottom, but a well integrated in the tank bottom where the feed line goes out.  The 3/8"  main feed line snakes into an 8" fine mesh sock located in the well chamber that is sandwiched under a first bottom.  You can't see the feed line because it is inside the sock and inside the well  - the hole to the well is about 2" dia.  The return line goes into the tank in different location in the tank than the main feed line - it diverges inside the tank. 
Well put some contraints on the challenge - these were essentially my constraints :
The job needs to be completed within 2 days - start to finish.  That is the car can be out of service for two days max.
There are no local welding shops that  will work on the tank and you live in an area with high labor premium where the cheapest labor is $35/hour.
You can do you own welding, but cost of welding materials needs to be factored into the cost.  
You can use if on hand, a MIG welder  or torch, but no TIG unless purchased inside the $200 price. (If anyone knows where to get a TIG for $200 I'd sure like to know.)
Incinerating or Blowing yourself up in process of welding does not count!
Shipping a fuel tank is restricted as hazardous cargo.
Fuel cell is acceptible fix, but must have 80% of the capacity of the original 22 gal. tank.
The fix needs to fit in the same space as the original tank and consume no less trunk space.
The fix needs to fit in trunk, engine bay, or  under the car in very limited space, and have ground clearance higher than the max travel of control arms and exhaust.
Know that the feed lines from the stock tank are barely accessible - a 60 deg. Bend in 3/8" feed pipe that is only 4" long coming out of a 5" dia. Hole in the trunk above the rear differential.  The return line is smaller - 1/4" I think.
The distance between the tank feed line and pump inlet is 15" and the path is not direct - there is subframe, trans. Mount. Obstructing the original line feed path from tank to pump, so existing plumbing take a convoluted route..
It needs to be safe - location can not be in proximity to any portion of exhaust.
Total cost of the fix needs to cost under $200 including parts and labor.
Extra points to solutions that retain original tank and plumbing from the pump to the engine bay connection fittings.
Solutions that cost more will be considered too, since I would have paid more if I needed to.
I did it with under $100 parts and 8 hours labor with one day down time.
Let's see what folks come up with.
Ben
[Date: Mon, 29 Mar 2010 12:09:37 -0400
From: qshipq at aol.com
Subject: Re: [urq] urq Digest, Vol 77, Issue 35
To: audionly at gmail.com, cody at 5000tq.com
Cc: urq at audifans.com, mdeltergo at hotmail.com
Message-ID: <8CC9D715D08AF11-1F34-2A10 at webmail-d049.sysops.aol.com>
Content-Type: text/plain; charset="us-ascii"
I agree with Peter, cavitation can be addressed before or after the pump.  Actually anywhere between the tank and the fuel rail.  This 'fuel capacitor' concept certainly can be mounted before the pump as Ben did it, but every HP application of this concept I've seen, is in the engine bay, regardless of pump location.  I would surmise the reason for this more common application, is less of a need to modify fuel tanks, fuel line diameter, and/or the risk of hanging a secondary fuel bomb under the car.
Scott J]
Original Post that started this all:
[Date: Fri, 26 Mar 2010 12:21:43 -0700
From: AF <afinn1 at gmail.com>
Subject: [urq] More Weird UrQ Behavior
To: urq <urq at audifans.com>
Message-ID:
<ed47d8be1003261221w2a4c5064v1f7af3a500956166 at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1 
So, at the past 2 track events I've attended with my V8 UrQ I have had a weird issue with engine cutout at high rpms, usually in 3rd gear, but on the straightaways in 4th gear. They seem to occur during any throttle position, like cresting a hill, or accelerating out of a corner, which is somewhat unnerving. There are no fault codes thrown at all, which makes me think it's a fuel supply issue. Here's the weird thing, I would say it a fuel pump relay issue, but wouldn't the engine stall (that's what my old UrQ and Coupe GT would do on the highway), but in this case there's no power until I depress the clutch after slowing a little and downshifting, then the power is all back. The engine never stalls and shuts off! I confirmed it's not a rev limiter issue by redlining with moderate throttle input and no issues occured. It's definitely at higher RPM though. Does anyone have a thought? I thought about relaying the fuel pump, but wouldn't the engine simply stall with no fuel supply, or will it simply keep running with the car in motion and clutch out without shutting down or turning on all the warning lights on the dash?
Any help is appreciated. Thanks. 
Andrew Finney
1985 UrQ 4.2L ABZ]