Hi All, I hope this is the right place to post this. I am looking for some suggestions on a fuel problem I am having. I bought this car last April on craigslist. It was in a field, under a tarp for 25 years. Needless to say, I needed to replace everything rubber as well as the fuel system, ignition system, cooling system, etc.. I put the car into great road worthy status and drove to the 50th Anniversary Riviera meetup in Lexington, last June from Las Vegas. Around Memphis or so, I started having an issue with the vehicle sputtering when I would be going up even the slightest incline, on the highway at around 70 with the cruise set, and at around 1/4 tank of fuel. I stopped and refilled the tank, and it would run fine. At the meetup, during a Q&A, I had asked about this to try and get some feedback. I got all kinds of good input from fuel pump to filter to canister potential issues. All this had already been dealt with, so I didn't worry about it at the meetup. On my way back, I had sort of an epiphany. In that, whenever I had stopped to fill up the tank, I would remove the filler cap and large amount of air would transfer. At first I didn't think much of this as I had experienced this when I was younger, with other cars, and just thought it was pressure building up. On my way back, at a fuel stop, I paid more attention to the "Whoosh" when I removed the cap, and discovered the air wasn't escaping, but rather was rushing "into" the tank, as a vacuum. It was then I realized the cap wasn't venting properly. I stopped by an Autozone, which happened to have the exact stock replacement for around $3.49, installed it, and the problem went away! I was able to run down to 1/8 or even a bit lower (just as a test, not my usual habit) and never had an issue, even on grades. So, this went on fine until yesterday. I don't drive the car very often but maybe once a month or so. I took a cruise yesterday and left with about 3/8 of a tank. As I was cruising down the interstate, I was hitting some mild grades uphill and all of a sudden it started the same type of sputtering, until I slowed down to around 45 or so, and then it ran fine, at least on level ground. At this point I noticed that I was right at 1/4 tank. I stopped, refueled, got back on the highway and it ran fine. And, just to let you all know, the sending unit has been replaced and is accurate, since when I do fill up at 1/4 tank, it consumes about 13~14 gallons, with a 19 gallon capacity. When I have had the tank out (at least twice) the baffle seems to be solid, in good shape and doesn't move around. So, I am looking for some advice from others as to what to look for and/or if this is just seemingly normal for this car and if others experience similar results. Any and all input is welcome. Thanks in advance.
Does this issue occur when you drive without the gas cap on? I remember this same incident being brought up on CarTalk. I'll see if I can find the article
I never actually tried running the vehicle without a gas cap, but by replacing it and having that "seemingly" fix the problem for almost a year. I am not sure what that would accomplish?
When gasoline is sucked out of the tank, air is supposed to able enter the tank so a vacuum is not created. Imagine "the office water cooler". As you pour water, that big air bubble is created, breaking the vacuum, allowing water to continue to flow. Now I know running without the cap on my Riv would result in a LOT if wasted fuel spilling out, so it might be best to just unscrew the cap when it starts acting up again, then re-tightening it. Not sure why your new cap went out after only a year though. If all else fails, it's possible for some vapor line to be blocked
I appreciate the input, but when this last incident took place and I stopped for fuel, when I loosened the cap, there wasn't any air transference what so ever. When I had discovered the original cap was bad last year, I would stop for fuel, and when I released the cap, there would be this huge "whoosh" of air entering the tank, ie the vacuum effect you are referring to. But, this no longer happens, and this is why I am slightly baffled.
