Hello Folk's,
due to the "wonders of internet shopping" the plan with the refurbished carb. from France did not work out: two Zenith carb. types on the HP - but both out of stock. Or to say it with my Grand-Dad's words: you can only sell what you have in stock...
- So true - even after 94 years!
So this was the end of plan A to solve the problem from the carb. side....
Plan b is, to solve it from the fuel supply side. In fact occured the problem of the choking engine at first, when I changed the "setup" from the cracked original petrol tank to a repro-one with a smaller fuel pipe diametre. When I bought the tank I did not recognize it, but in fact is the original pipe diameter something at about 9 mm and the repro-part from Belgium has only about 6 mm. - A silly mistake with consequences...
In addition I switched at that time from a mechanical pump to an electrical one, that my Dodge Brother Vario has in use in his WC54 Ambo.
- Without any problems, but in combination with the original tank and the larger pipe diameter...
So I had from the very beginning the repro tank fuel pipe as the suspicious part in focus, that is causing the problem.
My opinion is, that the smaller pipe diameter is causing a lack of fuel at full throttle. So as soon as the "fuel bowl" in the carb is empty at full speed the "choking" is starting. Just because the fuel consumption is higher than the amount of fuel that is coming thru the smaller pipe from the repro-tank.
So the new idea of mine is typical German: "pump up the volume" (that's from a 1990ies block buster song) and to rise the fuel pressure via adding a stronger fuel-pump or an additional second one.
The actual electrical fuel pump is sitting in the engine bay (dry and warm) and is linked to the hose after the original fuel filtre.
And yes: Normally you would position an electrical fuel pump directly behind the fuel tank, but there you have humidity and dirt and the risk of ripped off wire or hose in case of off-road driving etc. etc.
So the new plan to solve the problem is an additional electrical fuel pump, that is located directly after the fuel tank (as it should be).
This one (no. 1) has to "suck" the fuel directly from the tank at the max. psi pressure and the second pump located after ther original filtre is giving the additional boost to the fuel pressure for the "final mile" around the hot engine to the carb.
That second one has a valve for regulating the fuel pressure in addition and to prevent the carb. from overflow if the fiel pressure is too high at low speed.
That's the plan / theory - and tomorrow I will install the additional pump, that I bought today.
So (hopefully) that new setup is finished tomorrow afternoon and I can do some test-driving with it on the Autobahn....
...with positive results.
To be continued...
Joakim