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Finally got some free time to go after my passenger side fuel sender unit. Put car up on jackstands, removed wheel liner, X pipe and began process of going after the crossover tube.
Wow, what a pain. Return lines would not come loose from crossover tube. Had to use a crowbar (no joke) to pry crossover tube out, and then the lines came out with it still stuck. Finally was able to free the lines and get the gas tank out, but one of the O rings (large yellow) got cut in process. So now I can't find the O rings listed anywhere. Does anyone know where there is an on-line parts fiche that will zoom in so you can find parts your after? I tried GM Parts direct, but it doesn't show good detail and doesn't show the O rings I need.
Thanks, I already ordered new lines because the tabs broke off them where they fasten to the tank.
I'm amazed at the complexity of the fuel system in this car. It seems like they tried to make it much more complicated than it needed to be, and then tried to make it impossible to work on as well. What I found on mine was the small ferrel collar that presses in on the smaller lines had bonded to the lines in the crossover tube , making it nearly impossible to separate the crossover tube. The collar ending up pulling free from the interior tank line and staying with the line in the crossover tube. It would make more sense to simply put those two lines on the outside of the tank instead of inside the crossover tube.
I also don't understand why they didn't just mount the fuel pump and venturi unit in through a hole in the bottom of the tank. I've seen this done on many motorcycles. It seems like putting a high fail rate item like a fuel pump in a place that requires the entire drive line of the car to be removed to access a bad idea.
Last edited by CSixDude; Jan 18, 2019 at 08:55 AM.
I wonder how the C7 fuel pumps are done, anybody know? Are they still in the same location or did GM finally wise up and mount them through the bottoms of the tanks?
Not sure about C7 but the fuel senders were mounted on the bottom of the tanks on 03 an earlier C5's and when they went to this new fuel system on the last year C5 in 04 they moved them where they r now. I have done the right side sender on 2 cars and had the same problems u r having I just order the set of tanks side lines and the sender because the ears always break off and also had problems with the small o-rings. Haven't had problems with the large o-rings but each time I do one I have difficulty with something.
Make sure you have the 2 green wires coming off the sender in the correct places in the connector or u will be pulling it back out again. (Double check).
This system uses all the fuel in the right side tank first which I always thought was weird in a performance car where weight distribution matters.
Looks like the C7 shares the same flawed design, and adds to it with a second "high pressure" fuel pump. I've already read of several failures of this additional pump.
Leaky fuel supply systems plague Corvette C7 Stingray, C7 Grand Sport and C7 Z06 just like they did Corvette C5 and C6
Ironically enough, even though the convoluted design of the overly complex and counterproductive fuel supply system further reaffirms the contention that unless there is a good effort behind a design, things should be kept as simple as possible, it is mainly the use of plastic that causes the majority of fuel leaks that appear frequently and are permanently associated with the last three generations of Corvette.Specifically, inferior materials used in dual plastic fuel tanks, all sorts of plastic fittings and of course, the fuel pump assemblies belie the fuel leak problems. Add shoddy and inconsistent supplier build quality to quickly disintegrating plastic material and there is a strong potential for life threatening situation, should the owner of the car somehow miss or even worse, ignore the symptoms of gasoline leak or gasoline vapors surrounding the car.
Three main problem areas: fuel filler pipe, fuel pump and of course, the ever popular crossover pipe assembly which even though looks like it is made of metal, consists of more plastic junk merely surrounded by a metal disguise.At this time, the most popular problem appears to be related to the tank to crossover pipe connection that may be defective right from the get go, courtesy of shoddy suppliers (are they in China?) but… given some time, the trivial problems like filler pipe connection breaking off, fuel pump housing crumbling, vent lines breaking off, it all should be there, simply, because the design and choice of suppliers and materials has not changed at all. This situation is particularly ironic, given the fact +Tadge Juechter spent a lot of time convincing the buying public how much improvement the newest generation of Corvette supposedly is… Now, if only he and GM actually delivered on these claims.
Last edited by CSixDude; Jan 18, 2019 at 10:51 AM.
Thanks, I already ordered new lines because the tabs broke off them where they fasten to the tank.
I'm amazed at the complexity of the fuel system in this car. It seems like they tried to make it much more complicated than it needed to be, and then tried to make it impossible to work on as well. What I found on mine was the small ferrel collar that presses in on the smaller lines had bonded to the lines in the crossover tube , making it nearly impossible to separate the crossover tube. The collar ending up pulling free from the interior tank line and staying with the line in the crossover tube. It would make more sense to simply put those two lines on the outside of the tank instead of inside the crossover tube.
I also don't understand why they didn't just mount the fuel pump and venturi unit in through a hole in the bottom of the tank. I've seen this done on many motorcycles. It seems like putting a high fail rate item like a fuel pump in a place that requires the entire drive line of the car to be removed to access a bad idea.
I've done this job, and encountered all the same frustrations you did. I agree that the GM's execution could have been better, but I disagree that it's a bad design in principle.
The fuel system appears to have been designed with the primary objective of preventing fuel leaks, especially in an accident. The tanks themselves are positioned in the strongest part of the chassis. All of the pumps and plumbing and fittings live inside a tough, sealed assembly consisting of the two tanks and the crossover tube. This system has an absolute minimum of external joints. Adding access doors and whatnot would violate that objective and become another source of leaks.
The fuel system is non-return, so you have a single line that runs the length of the car, above the torque tube, right up to the braided connector at the fuel rail. And even the fuel rails are brazed together, further minimizing the number of joints that can leak.
Having worked on many cars that handle flammable, pressurized gasoline much more casually, some of which resulted in leaks and fires, I appreciate GM's paranoid design.
I would improve it just by tweaking the details: make the internal fittings out of metal instead of plastic so they don't fret together; put a big thread on the crossover ends so they press the assembly apart when unscrewed; increase the diameter of the hole on top by 1/2" so you can get the pumps in and out more easily. A few little changes would make this job much less difficult.
I've done this job, and encountered all the same frustrations you did. I agree that the GM's execution could have been better, but I disagree that it's a bad design in principle.
The fuel system appears to have been designed with the primary objective of preventing fuel leaks, especially in an accident. The tanks themselves are positioned in the strongest part of the chassis. All of the pumps and plumbing and fittings live inside a tough, sealed assembly consisting of the two tanks and the crossover tube. This system has an absolute minimum of external joints. Adding access doors and whatnot would violate that objective and become another source of leaks.
The fuel system is non-return, so you have a single line that runs the length of the car, above the torque tube, right up to the braided connector at the fuel rail. And even the fuel rails are brazed together, further minimizing the number of joints that can leak.
Having worked on many cars that handle flammable, pressurized gasoline much more casually, some of which resulted in leaks and fires, I appreciate GM's paranoid design.
I would improve it just by tweaking the details: make the internal fittings out of metal instead of plastic so they don't fret together; put a big thread on the crossover ends so they press the assembly apart when unscrewed; increase the diameter of the hole on top by 1/2" so you can get the pumps in and out more easily. A few little changes would make this job much less difficult.
I agree with (torquetube) all though there is certainly room for improvement on serviceability the system is OK with me. I have been working on cars all my life and there are always PITA jobs I just try to find better ways of getting them done. This forum is a great help for getting jobs like this done because we can learn from others experience. The plastic fuel lines are found in every late model cars I have worked on. Just did a gas tank in a Jeep this week which also had plastic fuel lines.
By the way, just incase you wondered, this is why Techron won't fix a failing fuel sender unit in this car. There should be five contacts on each row. More than half of them are bent or missing. Its a poor design and doesn't withstand the environment it is meant to operate in. The contacts are simply too fragile.
Last edited by CSixDude; Jan 18, 2019 at 05:56 PM.
Also, here is a link to another thread with lots of good pictures and info on getting the drivers gas tank out and replacing the fuel pump in case anyone needs it.
Are you sure they installed the proper replacement sender part number? My understanding is that there are several different part numbers for the sensor and you have to get the proper one for your year model.
Fuel Sender replacement
