hesitation and now no start

[scottyrocks]

I just installed a new accelerator pump diaphragm because I had one lying around. I had thought that maybe if it was torn that it would impact acceleration. But there was no change.

One of the four screws was missing (the one under the arm). Would that cause a running problem (there is no fuel leaking)?
_________________
“If you care for a thing long enough, it takes on a life of its own, doesn't it? Mending old things, preserving them, looking after them – on some level there's no rational grounds for it.”
– D. Tartt, 'The Goldfinch'

[scottyrocks]

[glutamodo]

The accelerator pump will only work if everything is clear. I alluded to this above when I mentioned the times I had gunk get into the brass nozzle, but the rest of the system still worked. The function of those two steel balls held captive inside the body of the carburetor are what makes the pump work. The smaller, upper one is closed by gravity and also by suction of the diaphragm, allowing fuel to be drawn in past the bottom ball when the throttle lever is released. When the throttle lever is opened, pressure generated by the diaphragm closes the larger bottom check ball, opens the top one and fuel gets sent to the brass tube.
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Andy T.


IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.

[scottyrocks]

Okay, then I will remove and blow out the brass nozzle first.

When I had recently serviced the carb I went as far as removing the check balls, cleaning the passages with carb spray, and reinstalling the balls.

I find it amazingly coincidental that the brass spray arm should get clogged immediately after changing the accel pump diaphragm, but this thread:

https://www.thesamba.com/vw/forum/viewtopic.php?t=688175&highlight=accelerator+pump+diaphragm

explains how today's rebuild parts could be enough off, dimensionally, to make them unusable.

And I suspect that I should go through the fuel system in a downstream direction beginning with the float bowl.

And because I still need some specs regarding the float bowl fuel level height, I will include here the post I had been working on this morning:


I figure, at this point, to go though the fuel system again, but this time moving downstream instead of jumping all over the place. At this point, I have gone as far as the fuel pump, where everything is up to spec. So now I am back at the carburetor.

The next stop on the Fuel Train journey is the float bowl.

I have just been through the chapters on Fuel System, Lubrication and Maintenance, and Technical Data in the Bentley manual, looking for the float height specs, which I have not been able to find here at the samba either (I'm sure they're here somewhere). I've read 12mm, 19mm, and no specifics about whether the float is installed or removed when taking the measurement. I'd like to get that part sorted for sure before I go any further with anything else, float height being so critical.

What I need to know, for the Solex 28PICT/28PICT-1:

What is the distance from the lip of the float bowl to the top of the fuel in the float bowl, or this even the correct way to make this measurement?

Is the float in place or removed when taking this measurement?

Once I know that the float bowl fuel level is correct, I can then move downstream, because what I have already done, listed below, won't matter until I know that the float level is correct.

I just replaced my accelerator pump diaphragm and now get no squirt from the brass arm in the barrel, whereas before I replaced the diaphragm, I did get squirt. This, in itself, is a problem, and needs correcting, regardless of the float bowl setting.

I have also used new gaskets in between the top and bottom of the carb, and under the carb where it meets the intake manifold. I now don't know how any of these gaskets, except probably the carb-to-manifold gasket, have upset the delicate balance of fuel delivery.

I have come to this realization after reading this thread:

https://www.thesamba.com/vw/forum/viewtopic.php?t=688175&highlight=accelerator+pump+diaphragm

I hadn't realized the extent of incorrectness of today's rebuild parts until reading that thread.
_________________
“If you care for a thing long enough, it takes on a life of its own, doesn't it? Mending old things, preserving them, looking after them – on some level there's no rational grounds for it.”
– D. Tartt, 'The Goldfinch'

[scottyrocks]

I took the car around the neighborhood and the idle is stable and the stumble is gone. At least for today.

On Andy's advice, I removed the brass arm and blew it out with carb cleaner. I was able to increase the flow as I continued to blow cleaner through it. So yes it was clogged.

While I was in there I removed the 'air correction jet with emulsion tube' (#10, p. K-1, K-1A, Bentley book), and blew carb cleaner through it, as well as the passage it's screwed into. The lower two of the three sets of holes were quite clogged. Repeated sprayings, and then reaming with a straw whisk, freed them up so that with the bottom hole plugged, there was a visibly good flow from all six side holes.

Before I removed it I noticed that it wasn't quite seated. Also, it wouldn't come out easily with the screwdriver. After everything was clean it screwed back in much more easily and seated all the way.

It being clogged and not in all the way could very well have contributed to the problem.

I also removed the main jet holder and main jet, and cleaned those, as well.

Now I just have to get on the charging problem. There is finally some light at the end of the tunnel.
_________________
“If you care for a thing long enough, it takes on a life of its own, doesn't it? Mending old things, preserving them, looking after them – on some level there's no rational grounds for it.”
– D. Tartt, 'The Goldfinch'

[glutamodo]

The air correction jet won't really affect idle or low end transition, it really only come into play at higher RPMs.

Acceleration/transition is mostly influenced by the accelerator pump and yes, you do want it to flow freely.

_________________
Andy T.


IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.

[scottyrocks]

[Dangermouse]

Glad you're making headway. A clogged accelerator pump jet would certainly contribute towards the problems you've been experiencing.

Just for your own interest you might enjoy this document if you've not seen it before -

https://www.thesamba.com/vw/archives/manuals/looklisten_11.php
_________________
Do not follow me, for I may not lead. Do not lead me, for I may not follow. Do not walk beside me either; actually just bugger off and stand over there will you.

[scottyrocks]

Well, it took long enough, but Ginger is now running, and running properly.

This, after the latest minor project of a partial generator service - new brushes and vreg.

No issues on the neighborhood test drive yesterday. Easy start, no missing, and no dash lights on after startup.

Next up is the installation of new heater cables.

I am happy, but guardedly so. haha
_________________
“If you care for a thing long enough, it takes on a life of its own, doesn't it? Mending old things, preserving them, looking after them – on some level there's no rational grounds for it.”
– D. Tartt, 'The Goldfinch'