run-on and excessive fuel consumption, 1965 Bug

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

wrote:
> 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.

<SNIP>

Hard to diagnose.

My vote is for carb float needle valve leaking.

Since you are in hot Arizona, fuel boiling can also be a problem.

If you mean run-on after switch off, the idle cutoff solenoid
on the carb *should* take care of that. Perhaps it is leaking.

Speedy Jim
http://www.nls.net/mp/volks/

First,
Remove the air cleaner and slosh it with kerosene. Then pre-oil it and let
it strain for a while before reinstallation.
Don't use other cleaning agents, especially water based stuff, as they might
be sucked in the idle circuits of the carb and cause corrosion to sensitive
calibrated components.

Between 20 and 30 mpg is a very wide range. Normal is 26-30 mpg, depending
on driving conditions.

About dieseling,
Besides checking that the needle valve closes and keeps the fuel level in
the carb's bowl in normal height,
check the electromagnetic cut-off valve.

The purpose of the electromagnetic cut-off valve is to cut-off fuel supply
on the idle circuit, so that when you turn off the engine, it won't run-on.

There are two wire connections to the carb, one for the heating element of
the electric choke, and the other for the solenoid of the electromagnetic
cut-off valve.
Remove the solenoid and test on a battery, if it clicks it works. You may
have to spray some WD40 in it until it moves freely again. In your carb it
is probably on the right side of it, and the idle jet is incorporated on it.
Spray the WD40 in the jet. Let it sit for some time, then respray and clean
it with compressed air.

Incorrect idle adjustment also causes dieseling.
The idle mixture adjusting screw must be responsive, when you turn it all
the way in the engine should stall, otherwise the carb needs to be cleaned.
Set it to the point that obtained idle speed is at it's highest, just before
it begins to drop. Then adjust idle to 850-900 rpm by the adjusting screw on
the throttle position lever (ONLY on older carbs, that didn't have the
bypass screw) or with the Bypass screw for newer carbs (the larger on the
left).
On newer carbs with the Bypass Screw, the throttle butterfly MUST be
adjusted to be almost completely closed (almost so that it won't bind on the
throttle body).


Bill Spiliotopoulos,
'67 Bug.



> wrote in message
ups.com...
> 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
>