72 Vapor condensor on tank

[Gary S.]

Does anyone have a close up photo of the vapor condensor attached to the fuel tank on a 72? I realize that I am probably butchering the correct nomenclature but it is the device attached to the top left of the tank (driver's side of course).

I went to our chapter's Judging School and parked on a minor incline and got fuel running out onto the muffler. I have known about this for a while but I guess I will tackle it before something serious happens. I need tosee how it attaches before I start crawling under the car.

Thanks,
Gary

[Harmon C.]

Re: 72 Vapor condensor on tank

Gary

I have no picture but they are attached by hex head bolts and as I recall about 1/4" hex and their are two. I heard some where this is a roll over or check valve. Many have cracked and most say their is no repo so they epoxy them up for reuse as the used supply are not cheap and hard to find.
Lyle

[Joe L.]

Re: 72 Vapor condensor on tank

Gary-----

The device which you inquire about is a fuel vapor seperator. It was used from 1970 (EEC cars only) to 1974 and was of GM #7028035. It was discontinued without supercession in May, 1986. That means it's been unavailable for just about 19 years. There is no reproduction available, as far as I know. The device serves, primarily, to seperate/condense fuel vapor returned to the fuel tank by the EEC system. A secondary function involves a check valve to prevent fuel spillage from the seperator if a "roll-over" occurs.

Unfortunately, the device is made of a fuel-resistant plastic which is one of the few types of plastic with which epoxies do not mend well. Epoxy can be used to repair these devices, but the durability/integrity of the repair is very questionable. I believe the material is linear polyethylene. Linear polyethylene is a very difficult plastic to repair with epoxy or, for that matter, ANY adhesive. The few adhesives that will work with it are not gasoline resistant.

My guess is that this is a part that's not been reproduced due to product liability concerns. I would expect that these concerns will continue and "discourage" firms from reproducing these. The 7028035 was a piece used only on Corvettes and some obscure MD/HD Chevrolet and GMC truck models. However, other model Chevrolets and other GM cars of the early to mid 70s used seperators of other part numbers. None of those are currently available from GM and, as far as I know, none are available in the reproduction or replacement markets.

[Jim T.]

Re: 72 Vapor condensor on tank

Gary is there any chance that your filler neck gasket could be leaking the gas?

[Patrick H.]

Re: 72 Vapor condensor on tank

Gary,

I repaired the one on Dad's 72 last fall right before I put the car away.
Let me know if you're around this week (send me a mail) and I'll give you a call to discuss.

Patrick

[Dick W.]

Re: 72 Vapor condensor on tank

According to a database that I use, Pacific Corvette in Palluyp, WA was, at one time, showing one in stock. Does not mean that they have one today, but it is worth a try

[Joe L.]

Re: 72 Vapor condensor on tank

Dick-----

Pacific Corvette is a great source. However, about 95% of the stuff they have is used. When they dismantle Corvettes, they strip off every usable part and inventory it by original part number as taken from the AIM or, in some cases, from P&A Catalogs. Their inventory lists do not normally differentiate between a used part of a certain part number and an new or NOS part of a certain part number. You have to call or e-mail to find out which it is. About 95% of the time, it will turn out to be used. In the case of these seperators, a used piece is better than no piece. However, in many cases, a part like these seperators will already have a significant, if not major, part of its life "used up".

[Gary S.]

Re: 72 Vapor condensor on tank

Joe, thanks for the input. I was aware that the unit is no longer made but I was hoping someone had a photo so that I can take it off and see if some "space age" shuttle type repair substance was available. The downside to buying any old plastic part is that, if my 36000 mile car has a leaking part, any replacement part is bound to be close behind it.

Patrick, I will be home all day Sat. and Sun. I welcome a call - got any photos of your repair - but I am also available during the day on my cell phone? Someone on the Corvette Forum posted a complaint about their fuel vapor seperator and got a reply naming a compound that should work. I hope to pull this off this weekend and at least ensure that it isn't something as simple as a hose versus the separator.
Gary
72 LT1

[Gary S.]

Re: 72 Vapor condensor on tank

Jim, 90% certain that the fuel filler neck gasket is ok since I only fill the tank about 70% full. I was aware that I had a leaking issue and my band-aid approach was to not fill it. Parking on an incline was enough to slosh the fuel to the area around the fuel vapor separator.
Gary

[Joe L.]

Re: 72 Vapor condensor on tank

Gary-----

That's the problem with this sort of part. It's a "consumable" item and very life-limited. In the case of this part, the life-limitation is more based on age, alone, than it is on mileage of the car it came off of. The NEWEST car that a used example of one these formerly resided on is a 1974 model (unless a SERVICE replacement obtained before the date of discontinuation). That means that any PRODUCTION-utilized seperator is a minimum of 31 years old.