[T3] Loses Power After Running

jadney at vwtype3.org jadney at vwtype3.org
Thu Sep 9 20:53:12 PDT 2021

On 10 Sep 2021 at 0:41, Tony Rongey wrote:

> I'm kind of wondering about the fuel delivery.  The coil is also suspect,
> because it was pretty hot after running.  It's blue coil which seems to be a
> hit or miss kind of thing.  I have an old black Bosch that I'll try this
> weekend, but it's untested so it might not help.

The OE Bosch black coils have been incredibly reliable. The Bosch Blue Coils, not so much, 
although I've always assumed that the German ones must have been good.

I'm thinking fuel delivery, too. If you don't have a low pressure gauge, it should be possible 
to make a manometer with a branch in the line from the pump to the carbs. If the branch is 
clear plastic, you can measure the vertical height that the pressure can push the gas up the 

A very quick & dirty calculation predicts that 3.5 psi should push gasoline up about 5.2 feet. 
It will go proportionally higher if the pressure is more than 3.5. This will not be easy to do, so 
it's probably easier to find a cheap gauge. My gauge for this would be a cheap J C Whitney 
gas pressure/manifold vacuum gauge.

If you measure the pressure, either way, don't worry about the actual number. The point will 
be to compare the pressure that you have when running well with the pressure when the 
engine gets weak. They should be the same. If they're not, you've probably found your 

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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