Got an odd Weber issue with one of my newly rebuilt Weber 40 IDA 3C carbs on my 914/6 swap that I was wondering if some of you can help me out with?
Starting the car is a bit tricky but nothing too unususal for a carbed car. Once started the car runs reasonably well; it idles nicely and takes throttle decently well for a car with un-synced carbs at this point. I've taken it for two test drives thus far and both times after about a mile or so the car starts starving for fuel. After the second time it happened I was able to ascertain that passenger carb was not shooting fuel out of the accel jets. After popping off the top of the carb my suspicions were cemented as both bowls were completely dry.
Now to the crux of the matter......why is this happening? The bowls are filling initially on start up, but then just drain out and don't fill back up under load while driving. I checked to make sure that the carb was getting some sort of fuel delivery with the top of the carb off,...it was. If the car sits for a couple minutes it seems to then repeat the cycle.
My first thought would be the needle valves, but they are both new valves out of the rebuild kit and it seems unlikely that they both would be acting up as BOTH bowls are emptying and not filling back up.
Second thought was float levels, but this seems somewhat unlikely as well as it would not explain why the floats fill up initially but not thereafter. Seems like it should be consistently inconsistent if the float levels are off if you catch my drift.
The most plausible explanation I can come up with at this point is weak fuel pressure. The fuel pump may be strong enough to get the carb filled on start up, but once it gets hot and is working under load it pressure capacity may be weakening. Also the car sat for a good bit while in the possession of a buddy of mine and when I checked the fuel filter in front of the pump yesterday it was FULL of crap and crud. Some of this crap and crud definitely got past the filter as the carbs had a lot of junk in them too....hence the rebuild.
I'm going to start off tomorrow by testing, and perhaps swapping, fuel pumps. Was wondering if any of you Pelicanites might have some additional ideas of what else I should check while I'm literally elbow deep in Porsche tomorrow?
As always all input will be greatly appreciated
