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I know the gas tanks are right behind the seats, but I believed I had clearance towards the top.
I drilled behind the passenger seat downward in the location of the red arrows.
I had the drill bit stop collar set so that I barely pierced the metal. Both hole seemed to drill fine. And rivets went in freely.
But upon using the dust buster to clean metal shavings, I smelt the faint smell of gas being shot out of the dust buster.
it was the hole towards outside of the car (basically the furtherest hole from the gas tank vent). And I really had to put my nose directly to the hole to smell anything. But there was the faint smell of gas from only the one hole. Could this faint smell possibly be normal? Or should I drop the passenger tank and check for any damage or leaks?
When I put the interior back together I smelt absolutely nothing. But obviously that could change when I start the car. I currently only have 1/4 tank so maybe that’s why the smell is so faint?
Bill Curlee has posted some excellent photos over time, depicting extremely valuable information on just about everything, including this situation. The good news is you couldn't have drilled the fuel tank. The bad news is that if everything added up poorly, you could have pierced the cross-over tube. I for one doubt it, thinking what you probably have done is vented the area the cross-over tube occupies, and caught a small amount of vapor. You filled the holes with pop rivets, which will probably halt the vapor, unless the rivet shank falls out over time.
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Photo is from an older thread: https://www.corvetteforum.com/forums...-pressure.html
Thank you for the reply
This is why I love this forum!
The smell of gas wasn’t strong at all. I had to leave the garage and come back minutes later and sniff again directly into the hole to smell it. I poked around in the hole with a dental pick and didn’t feel anything in the way of where I had drilled.
i have a ‘98 with the older style cross over tube. (Also making it easier to drop the tank, if need be).
I want to agree with you and say I vented a pocket of gas vapor. But If I DID pierce the cross over tube, would it start leaking once I started the car? Would I need more than 1/4 tank?
The irony of all this, is I drilled these holes to mount a fire extinguisher ��
awesome link too by the way!!
Last edited by Vetteman Jack; Mar 26, 2019 at 03:50 PM.
Not to jab at you but I don't know why you would have tried to mount an extinguisher there. It would be difficult for you to try and reach behind the passenger seat in an emergency situation. If I were mounting one I'd mount it in front of where the passenger seat is. Just move the seat all the way back and mount it there. If someone does sit there their legs go over the extinguisher, and so it doesn't obstruct them.
The cross over tube has to be under pressure as the system itself constantly pushes fuel to the drivers' side tank. The way the fuel system works is while the driver's side tank pumps fuel through the standard electric pump the passenger side tank has a siphon that pulls fuel from it and dumps it to the drivers'. The idea is that the tanks themselves maintain both a (relative) level of weight on each side and so one side doesn't empty first. Obviously in performance driving situations you'd probably have a weight discrepancy at some point side to side especially with weight of the driver, but it's not much.
Even if you pierced the cross over just a tad bit you will have compromised the fuel system, and you'll need to drop both tanks and check everything.
Not to jab at you but I don't know why you would have tried to mount an extinguisher there. It would be difficult for you to try and reach behind the passenger seat in an emergency situation. If I were mounting one I'd mount it in front of where the passenger seat is. Just move the seat all the way back and mount it there. If someone does sit there their legs go over the extinguisher, and so it doesn't obstruct them.
The cross over tube has to be under pressure as the system itself constantly pushes fuel to the drivers' side tank. The way the fuel system works is while the driver's side tank pumps fuel through the standard electric pump the passenger side tank has a siphon that pulls fuel from it and dumps it to the drivers'. The idea is that the tanks themselves maintain both a (relative) level of weight on each side and so one side doesn't empty first. Obviously in performance driving situations you'd probably have a weight discrepancy at some point side to side especially with weight of the driver, but it's not much.
Even if you pierced the cross over just a tad bit you will have compromised the fuel system, and you'll need to drop both tanks and check everything.
It is a perfectly acceptable jab because I know the tanks are right there and I drilled anyway. As far as mounting preferences, that’s a very accessible spot for me to reach. I originally had it on the passenger seat bracket but passengers weren’t fond of it being under their legs.
Would the crossover tube be under pressure with the key to accessory? Or the car has to be running?
If I punctured the fuel system I’d expect a stronger smell of gas. But I only had 1/4 tank. And like you said, the cross over tube wasn’t under pressure.
This is a tough one. Don’t know if I should run the car and check for a drip / stronger smell of gas. Might cause me to use that new extinguisher soooner than later.
Not to jab at you but I don't know why you would have tried to mount an extinguisher there. It would be difficult for you to try and reach behind the passenger seat in an emergency situation. If I were mounting one I'd mount it in front of where the passenger seat is. Just move the seat all the way back and mount it there. If someone does sit there their legs go over the extinguisher, and so it doesn't obstruct them.
The cross over tube has to be under pressure as the system itself constantly pushes fuel to the drivers' side tank. The way the fuel system works is while the driver's side tank pumps fuel through the standard electric pump the passenger side tank has a siphon that pulls fuel from it and dumps it to the drivers'. The idea is that the tanks themselves maintain both a (relative) level of weight on each side and so one side doesn't empty first. Obviously in performance driving situations you'd probably have a weight discrepancy at some point side to side especially with weight of the driver, but it's not much.
Even if you pierced the cross over just a tad bit you will have compromised the fuel system, and you'll need to drop both tanks and check everything.
That's not how the fuel tanks work in a C5. The crossover tube isn't pressurized. it's more of a spillover so when the left tank is full, fuel runs across the crossover tube to the right tank. The right tank empties first, then the left with the pump keeping the left tank full. There was a really easy to understand write up floating around but with so many fuel sending unit issues you could probably just search "techron" to find it.
The spot I drilled is right above the gas vent pipe. Is it possible I smelt the vent pipe? Assuming it vents to atmosphere? There is no more smell of gas. I’ve primed the fuel system several times with the key and no leaks or smell. but I’m not sure if this would tell me anything because the car wasn’t running.
Diagram Spot where I drilled
Last edited by h0ckeyfreek20@yahoo.; Mar 25, 2019 at 09:59 PM.
No remotely modern vehicle vents fuel vapor to air, it's always collected and eventually burned via the vapor canister. If, and it's a big if, you pierced the vent line you will know it pretty fast by a CEL, probably the same CEL a loose or worn fuel cap develops. I would think that when it doesn't develop a sudden increase in fuel vapor CELs you'll know you didn't pierce the vent line. I say a sudden increase, since I know I haven't hurt mine, and I get the occasional CEL for fuel vapors, and so do others I'm familiar with. I clear it, and it goes away for a considerable length of time.
Turns out I didn’t hit the tank. Dropped the passenger tank and could see the scratch marks where I probed with a dental pick. No holes and tank is fine.
One thing I don’t understand is that I reviewed maybe 6 different diagrams for different evap systems, cross over tubes, etc for the C5. And mine wasn’t similar to any of them.
Mine was literally just two fuel lines and a sensor coming off the pump, the cross over tube, and above the cross over tube was just a soft vent hose that went back towards the drivers side tank. And that’s it for the tank to completely come down. All the diagrams I saw were way more complicated than that.
Last edited by h0ckeyfreek20@yahoo.; Mar 28, 2019 at 04:36 PM.
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Gas tanks.
