Idling problem

Hey all,
Just put a rebuilt and rebushed 28 PICT on my '63 40hp Bug and am having a
problem with it idling once the choke is off. It idles fine when just sitting
there, but when deaccelerating to a stop on the road it want to die unless I
goose the accelerator pedal and resotre the idle at which point I am fine until
the next stop sign. It runs fine at all speeds and accelerated fine, it just
will not hold idle when I come to a stop. Any ideas? I am assuming it is the
carb. I set the mixture screw per directions (2.5 out then in half turn after
finding the point where the engine idles fastest). I installed new points,
plugs, adjusted the valves and timing per specs. Any ideas are welcomed.
--Dan E

Braukuche wrote:
>
> Hey all,
> Just put a rebuilt and rebushed 28 PICT on my '63 40hp Bug and am having a
> problem with it idling once the choke is off. It idles fine when just sitting
> there, but when deaccelerating to a stop on the road it want to die unless I
> goose the accelerator pedal and resotre the idle at which point I am fine until
> the next stop sign. It runs fine at all speeds and accelerated fine, it just
> will not hold idle when I come to a stop. Any ideas? I am assuming it is the
> carb. I set the mixture screw per directions (2.5 out then in half turn after
> finding the point where the engine idles fastest). I installed new points,
> plugs, adjusted the valves and timing per specs. Any ideas are welcomed.
> --Dan E


Check fuel level in the float chamber. Might be too low.

Jan

>Check fuel level in the float chamber. Might be too low.
>
>Jan
>

How do I check it? And what level should it be at? And how do I adjust it?
Thanks,
--Dan E

Braukuche wrote:
>
> Hey all,
> Just put a rebuilt and rebushed 28 PICT on my '63 40hp Bug and am having a
> problem with it idling once the choke is off. It idles fine when just sitting
> there, but when deaccelerating to a stop on the road it want to die unless I
> goose the accelerator pedal and resotre the idle at which point I am fine until
> the next stop sign. It runs fine at all speeds and accelerated fine, it just
> will not hold idle when I come to a stop. Any ideas? I am assuming it is the
> carb. I set the mixture screw per directions (2.5 out then in half turn after
> finding the point where the engine idles fastest). I installed new points,
> plugs, adjusted the valves and timing per specs. Any ideas are welcomed.
> --Dan E


Check fuel level in the float chamber. Might be too.....high. <g>

Seriously. Minor flooding becomes apparent at idle where at
highway speeds the consumption is enough to mask it.

Can be caused by float needle valve not seating or not screwed in
tightly. The 28 carb is less affected by fuel boiling (is it hot
where you are?) but a possible.
Probably not fuel pump pressure (if stock).

Any chance of vacuum leaks?
Richen the idle mixture slightly and see if that solves it.

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

>Can be caused by float needle valve not seating or not screwed in
>tightly. The 28 carb is less affected by fuel boiling (is it hot
>where you are?) but a possible.
>Probably not fuel pump pressure (if stock).
>
>Any chance of vacuum leaks?
>Richen the idle mixture slightly...<<

Doubt if it is a boiling issue since the temps are quite mild and the engine
runs cool. Fuel pressure seems fine, as it is not starving at speed. As for
leaks, I just replaced athe intake seals and everything is hooked up on the
carb. I am thinking its the fuel level in the float chamber but not sure how I
measure that and adjust it.
--Dan E

Braukuche wrote:
>
> >Can be caused by float needle valve not seating or not screwed in
> >tightly. The 28 carb is less affected by fuel boiling (is it hot
> >where you are?) but a possible.
> >Probably not fuel pump pressure (if stock).
> >
> >Any chance of vacuum leaks?
> >Richen the idle mixture slightly...<<
>
> Doubt if it is a boiling issue since the temps are quite mild and the engine
> runs cool. Fuel pressure seems fine, as it is not starving at speed. As for
> leaks, I just replaced athe intake seals and everything is hooked up on the
> carb. I am thinking its the fuel level in the float chamber but not sure how I
> measure that and adjust it.
> --Dan E

I'm not as familiar with the 28, but later carbs have a fuel
level ~3/4" below the rim. Measure that with the top
off and the float in place. I'd be very surprised if it is off
and even more surprised if it materially affected idling.
It's adjusted by adding washers under the needle valve.

Since you did replace the manifold seals, they are a prime suspect.
It's not unusual for new seals to leak a bit. That can create
enough of a leak to upset idle mixture. Spray around them with
solvent and see if RPM changes.

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

>Since you did replace the manifold seals, they are a prime suspect.
>It's not unusual for new seals to leak a bit. That can create
>enough of a leak to upset idle mixture. Spray around them with
>solvent and see if RPM changes.
>

I did that and no difference in idle speed. I did go ahead and replace the
float needle valve with another original one. I did notice that there was gas
in the bowl and the float was all the way down, in other words the float was
not floating cause there was not enough gas. That did not seem to make a
difference. I also let the mixture scew out more, about one complete turn and
that did make a difference it seems to idle better for the moment. When you
turn the mixture screw out does that richen or lean out the mixture? I can
never remember.
--Dan E

Braukuche wrote:
>
> >Since you did replace the manifold seals, they are a prime suspect.
> >It's not unusual for new seals to leak a bit. That can create
> >enough of a leak to upset idle mixture. Spray around them with
> >solvent and see if RPM changes.
> >
>
> I did that and no difference in idle speed. I did go ahead and replace the
> float needle valve with another original one. I did notice that there was gas
> in the bowl and the float was all the way down, in other words the float was
> not floating cause there was not enough gas. That did not seem to make a
> difference. I also let the mixture scew out more, about one complete turn and
> that did make a difference it seems to idle better for the moment. When you
> turn the mixture screw out does that richen or lean out the mixture? I can
> never remember.
> --Dan E

Screw out will make it richer.
The float should definitely float...high enough to have
tripped the needle closed. If the new needle didn't fix that
then there is still a problem.

Jim

>Screw out will make it richer.
>The float should definitely float...high enough to have
>tripped the needle closed. If the new needle didn't fix that
>then there is still a problem.
>
>Jim

Then I'll have to pull the top again and check it. Maybe the pump is bad but
its odd that it doesn't shop up at speed...
--Dan

Braukuche wrote:
>
> >Screw out will make it richer.
> >The float should definitely float...high enough to have
> >tripped the needle closed. If the new needle didn't fix that
> >then there is still a problem.
> >
> >Jim
>
> Then I'll have to pull the top again and check it. Maybe the pump is bad but
> its odd that it doesn't shop up at speed...
> --Dan

Yes, I agree about the "at speed" part. Another puzzle...
Jim