I've been reading posts on this website for a long time now, but this is my first post. And since I can usually take care of problems on my own, it's going to be a long post.
I've got a 1965 VW Type 1, stock 1200, 6 volt. Bahama Blue. Name: Frauline. My grandfather bought it new in 1965 and gave it to me in
2002. He took excellent care of it, he was a mechanic in the war and is obsessive about automotive maintenance.Problems: excessive run-on (dieseling) and excessive fuel consumption.
So originally, some months ago, the car didn't have any serious problems. Then I made the possible mistake of getting gas from Costco. A friend had needed a lift there, and in return offered to let me use their membership card to get cheaper gas. I have no idea whether or not this is related, but it may be a factor. Seems suspicious. I've heard that the gas is low quality.
So like a week later I was driving along and suddenly the engine started running really rough. Missing, sputtering. I thought I was going to have to pull over immediately, but I nursed it home. After some testing, I realized that I wasn't firing a cylinder. I removed the spark plugs, and it was textbook carbon fouling. So I replaced them. And while I was at it, I re-set my distributor point gap and of course my ignition timing. I figured the carbon was from bad timing. Things seemed okay.
So maybe another week later, I started having run-on problems. Slow onset, gradually getting worse. I got the genius idea of cleaning my air filter, it was the original oil bath. I got the idea from a website, maybe this one, I can't remember. I thought it wasn't getting enough airflow into the carb and this was making the mixture too rich and causing run-on and carbon. So I washed out both halves thoroughly and soaked them in a trisodium phosphate (it's a cleaning agent, I got it from Ace) and it took like 5 washes before the top half was clean. I don't think it had been cleaned in 42 years. I decided to dry the filter medium by putting it in the oven at a low heat for about
20mins. This seemed okay, the metal only got sort of warm, although the medium looked a little singed. I didn't think much of that. So I put it back on.It didn't really help. So I adjusted the idle mixture and speed, according to my Chilton's instructions. I also replaced the fuel filter and tightened the generator belt. It had been running great, until it started missing again sometimes. Given the missing and run- on, I switched from regular-grade gas to medium-grade gas. That cleared up the missing problem, that's totally resolved. But the run- on hasn't changed.
So, she's been driving great, I can hear that she is more in tune. But still running on, or "dieseling", and very badly now. Even for a short drive, it will happen almost every single time. Last month I noticed that I was going to the gas station a bit too often, so I started tracking my fuel economy. I'm only getting between 20 and 30 mpg!
I'm stumped. I feel like I've tried everything. Tuning up everything, switching to better gas. I even sprayed the manifolds with WD40 to see if there was a leak (if there was a leak the WD40 would get sucked in and cause the engine to rev up for a moment). I had the carb rebuilt only 1 year ago, last summer.
I mean, I live in Arizona. It gets damn hot in the summer. Sometimes she'll run a little rough under strain or high speed, I'm kind of used to that, it only happens when it's hot. Could the run-on just be the heat? It's never been a problem during other Arizona summers. I thought about carbon hot-spots, but that seems unlikely, it wouldn't run so well. Bad compression or timing? Doesn't seem likely, a 4- stroke like this wont run if it's so far out of tune that I'm losing so much of my MPG. I don't see any gas leaking out of the exhaust or onto the ground. My oil level is fine, I use Castrol straight 40 weight.
Is it possible that some bit of the air filter medium broke off from being dry and jammed into the carb somewhere? Should I just rebuild it? It's kind of a commitment to do anything like that, because this is my only ride to work every day.
Any help or ideas or similar stories would be GREATLY appreciated.
Thanks, Tom