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josua

Seasoned Member
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Nov 13, 2016
Messages
96
Location
Gibsonia, Pa
My XLR/V(s)
2004 Raven Black xlr 2009 sts4
Just a thought. Why would an engineer design a car with 2 fuel tanks WITH a crossover, then put a separate fuel pump and sensor on each tank! What is the point! Lets just over-complicate things to **** you off. Sorry for venting.
 

Gord

Seasoned Member
Joined
Oct 15, 2019
Messages
213
Location
Montreal, Canada
My XLR/V(s)
2004 #67
Hi Josua,
Well, it wouldn't have been the first, that's for sure.

Ponder this: there's a limited amount of space yet a requirement for a reasonable amount of fuel. There's a driveshaft (tube) running down the center of the car and a transmission and a differential occupying most of the rear center. Two tanks would handle the volume needed, now how to control what fuel goes where?

If you step through the design philosophy / criteria, it's kind of essential that each tank can 'cooperate' with the other. I have not studied this particular system, instead others, and usually one tank registers it's level and has the ability to pump over to the other. That second tank pumps to the engine and must of course register its level as well - tell tank one to move more fuel if needed and available, and tell the driver the quantity available. And don't forget about fill-ups - we need to get fuel in to both tanks and at a reasonable rate!

I'll have to look it up to study the specific workings of the XLR setup but ultimately I would speculate that 'fuel tank design and placement' fell in line quite well after many of the other major components. And really, it's not that rare. Keep the tank(s) low, keep them somewhat balanced left to right, keep them somewhat centered (front to back) in the chassis makes them safer from impact.

Ah, that reminds me of something you may or may not recall depending on your age. :lol:

 

James Landi

Seasoned Member
Joined
May 21, 2017
Messages
141
Location
Camden, Maine, and Melbourne, Fl.
My XLR/V(s)
2007 (red) with wire grrile
Gord,

Thank you for your thoughtful explanation, as well as your Youtube posting. As is the case with many moral dilemmas, not everyone is going to agree... and as stated in the video, the analysis presented provides a "utiliitarian" philosophical/financial perspective, which, as know, the company adopted. Certainly, some of the folks on the Ford board and administration would have second thoughts if they were trapped in a burning Pinto, but then, I suspect they never set foot in one. James
 

pure zen

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Joined
Mar 12, 2014
Messages
841
Location
AZ
My XLR/V(s)
2005 Crimson Pearl XLR

josua

Seasoned Member
Joined
Nov 13, 2016
Messages
96
Location
Gibsonia, Pa
My XLR/V(s)
2004 Raven Black xlr 2009 sts4
I understand why the two tanks. I don't understand why there's a fuel pump and sensor on each tank when there's a crossover line connecting them. The fuel level would be the same on both tanks. If not, what happens when you fill up your car?
 

Gord

Seasoned Member
Joined
Oct 15, 2019
Messages
213
Location
Montreal, Canada
My XLR/V(s)
2004 #67
I understand why the two tanks. I don't understand why there's a fuel pump and sensor on each tank when there's a crossover line connecting them. The fuel level would be the same on both tanks. If not, what happens when you fill up your car?

Hi Josua,
Two tanks joined by one line, however the line isn't at the bottom and can't set a single fluid (fuel) level. It's towards the top - it has to be because of the driveshaft / torque tube and ground clearance.

Now we need some way to pump fuel up and over from let's call them 'the slave' tank and to 'the master' tank. Again, I can't say exactly with the XLR but other twin-tank arrangements will decide to run the 'cross-over' pump in the slave tank as the car is refueled based on the master's level and / or its level versus the slave's.

There is also the possibility that during refueling, the slave pump doesn't run at all. Depending on the cross-over pipe size, in theory you could fill the slave tank until it reaches the level of the cross-over pipe - now it will spill in to the master, and once they are both filled, it will be up to the nozzle to say stop - I'm full.

HTH!

Gord :thumbsup
 

IAN

Seasoned Member
Joined
Feb 19, 2015
Messages
496
Location
Province of Québec
My XLR/V(s)
2004 silver XLR
Josua

My opinion is that the fuel reservoirs are just an other feature from the corvettes, its shape made of plastic is for the safety in case of an accident, the plastic '' bag '' do not makes a sparks to get the fuel turning into fires.

Most sports cars do use this system.... been forward of the car, the weigh distribution could be just better.

The 2 reservoirs actualy are like one unit as the fuel lines are getting them together thrue the center flexible tubing, the fuel pump then feed the engine.

Each reservoir has a fuel level sensor comunicating together for the actual level.

When filling the car with fuel the gravity fills the first reservoir and then the second one.

Enclosed is a drawing showing the function of the fuels reservoirs.

Thanks for the question.

IAN

fig2c5fuel.jpg
 
Last edited:

Z1.

Seasoned Member
Joined
Apr 11, 2013
Messages
168
Location
Fallbrook
My XLR/V(s)
2006 Raven Black XLR
I completely agree with you. The design is just asking for problems.
 

josua

Seasoned Member
Joined
Nov 13, 2016
Messages
96
Location
Gibsonia, Pa
My XLR/V(s)
2004 Raven Black xlr 2009 sts4
OK guys, makes a lot of sense. One more question, which tank is #2? Tech II says #2 fuel sensor has a problem. Not ready for that bill. I think if I had an exact layout of the trunk floor and tank position, I'd cut a hole in the trunk floor and make the job a lot easier.Just sayin.
 

Z1.

Seasoned Member
Joined
Apr 11, 2013
Messages
168
Location
Fallbrook
My XLR/V(s)
2006 Raven Black XLR
I had to replace an EGR hose from the right tank last year (damn *^%$ mouse). This is crude, but I worked for me. Take off both back tires, (raise the vehicle first, obviously) remove the wheel liners, you will be able to see each tank top ports on each side. Take the trunk liner out, drill a pilot hole up through the floor in the general location of each port, then use a 3" circular bit from the trunk downward. It's fiberglass, so use a water sprayer, glasses and N95 mask. I used an aluminum square siliconed on the trunk floor to patch. I only had to make one hole, a frame brace was partially in the way and wires, but I think a pump could be pulled out.
 

Gord

Seasoned Member
Joined
Oct 15, 2019
Messages
213
Location
Montreal, Canada
My XLR/V(s)
2004 #67
OK guys, makes a lot of sense. One more question, which tank is #2? Tech II says #2 fuel sensor has a problem. Not ready for that bill. I think if I had an exact layout of the trunk floor and tank position, I'd cut a hole in the trunk floor and make the job a lot easier.Just sayin.

Hi Josua,
I can't tell you which tank is #2 but first....if someone else doesn't chime in, dig around here in the threads, even fairly recently: there's all sorts of mention of fuel additives that seem to cure fuel sender problems with little more than a few tank-fulls and some driving around. Beats the tar out of drilling holes imho.

Gord :thumbsup
 

Z1.

Seasoned Member
Joined
Apr 11, 2013
Messages
168
Location
Fallbrook
My XLR/V(s)
2006 Raven Black XLR
Yea, Gord is right, keep trying the fuel additives; hole drilling = last resort. Tank 2 should be on the passenger side.
 

IAN

Seasoned Member
Joined
Feb 19, 2015
Messages
496
Location
Province of Québec
My XLR/V(s)
2004 silver XLR
Gas reservoir # 2

Josua.

The unpair numbers are for the driver side and the pair numbers are for the passenger side, so the reservoir 2 is on the RH side.

Also since the gas filling, feeding the engine and the fuel pump is on the driver side, this reservoir is mainly the one that feed also the #2 reservoir.

As far is for opening the floor to reach the reservoirs I do not think it is a wise decision as you will spend more time in doing so then perhaps doing the way it should be done.

Removing/installing it is mostly labor time, if you are an handyman you should doing it the proper way, get your self a workshop manual, see on you tube/internet the C6 fuel tank replaced, there are many videos ..... take the proper decision .

Good luck :wave:
 

Z1.

Seasoned Member
Joined
Apr 11, 2013
Messages
168
Location
Fallbrook
My XLR/V(s)
2006 Raven Black XLR
GM repair procedure for fuel pump replacement requires removing the drive shafts, differential and transmission. On vehicles this old, no mater how careful you are, these parts will break. It's one a hell of a job. Most mechanics, one thousand dollars and up. Dealership...Ha Ha. Go easy, I live in Cali, things are stupid expensive here.
 

IAN

Seasoned Member
Joined
Feb 19, 2015
Messages
496
Location
Province of Québec
My XLR/V(s)
2004 silver XLR
Gas reservoir /tank

Hi Z1

I agreed with you, on the other hand i dont know if he is as good as you did for the XLR gas tank problem, we dont have many members who were able to fix it.

Saying that i sugested him to get a workshop manual and to get first informed on internet about the same problem that some c6 corvette fans were able to solve this problem.

That will be josua to decide.

It would be great if you would make a thread in explaining us how in details , you were succesfull in fixing this gas tank problem your owne way..... it would help all of us.

Thanks for your post.

IAN:thumbsup
 

Z1.

Seasoned Member
Joined
Apr 11, 2013
Messages
168
Location
Fallbrook
My XLR/V(s)
2006 Raven Black XLR
I never have actually removed a XLR fuel pump, so I can't say what I did will work and I'm not too sure of the wisdom of being in the trunk over an open fuel tank. No smoking please.
 

RBrown

Active Member
Joined
Nov 16, 2015
Messages
36
Location
Tavares, FL
My XLR/V(s)
2006 Infared
I had mine done a few years ago. They had to drop the suspension and then the tanks to get to the pumps. They found numerous other things deteriorated so all in it was about 4000. Car has been flawless since. It’s a big chunk of money but I guess it’s worth it


Sent from my iPhone using Tapatalk
 

IAN

Seasoned Member
Joined
Feb 19, 2015
Messages
496
Location
Province of Québec
My XLR/V(s)
2004 silver XLR
Fuel tank access.

Hi Z1

After checking, it looks that doing an opening on the trunk floor in order to reach the fuel tank it could be hard, as there is a triangular plate attached to the frame were it gets wider on each side.

The fuel tanks are just lower this reinforcement plate.

See the attached photo of a Corvette with a similar frame then the XLR.

An issue to concerned all members.

IAN :wave:

corv_chass - Copie.jpg
 

mickeytee

Seasoned Member
Joined
Apr 5, 2017
Messages
773
Location
North Atlanta
our cars are corvette c6 based and not c5 as photo above but there is still no real access from the top plus as one member said, you will find hoses and lines that will need to be replaced while you are at it
xlr chassis.jpg
 

IAN

Seasoned Member
Joined
Feb 19, 2015
Messages
496
Location
Province of Québec
My XLR/V(s)
2004 silver XLR
Fuel tanks

Good shot sally.

This c6 frame is without the body core, enclosed is an other shot of a cutaway c6, this time with its body core, as you can appreciate it is also very alike a c5.

You can see ( thanks to cutaway ) that the fuel pump is under need of the transversal body reinforcement, cutting it there it would weak its struture and its lower triangular panel.

IAN.:blinzel:

C6cut004.jpg
 

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