Musings on Vacuum gauges and fuel pressure gauges

[Doug Yoder]

On my 100 FWD (NG-style NF engine), there are two ports into the plenum 
area of the intake manifold (kind of directly above the valve cover). 
IIRC, one is there for the AC system, and one for the quattro - since my 
car is FWD, the port for the quattro is capped off, and makes an 
excellent place to attach your vacuum gage.  On Dennis's 100Q, I think 
it would probably be OK to temporarily disconnect the vacuum line to the 
AC, or definitely OK to use some spare hose and make a T fitting on one 
of those ports.

-Doug

SJ wrote:
> Denis brought up some interesting points in his troubleshooting research.
> 
> I was wondering where/how he hooked up the vacuum gauge to the intake
> manifold. Besides drilling and tapping a threaded hole in the manifold, does
> anyone have a better idea? Is there a vacuum port on the side or underside
> of the manifold that can be exploited for this task?
> 
> Regarding the fuel pressure testing.
> Where can you get the special fittings needed to attach the fuel pressure
> gauge to the fuel lines?
> I already have a fuel pressure tester, but not the special fittings.
> 
> Another thought on fuel flow and pressure testing.
> In the audi CIS system, not only is fuel pressure important, but so is fuel
> flow.
> 
> I was thinking of using a flow meter in conjunction with pressure testing.
> The flow meter would consist of a vertical clear tube with a ball inside.
> The ball would be non floating, and be smaller in diameter than the inside
> diameter of the tube.
> To use, you connect the tube in series with the fuel line. Stand the tube
> vertically. The gas pushing against the ball and streaming past the ball in
> the tube will lift the ball indicating fuel flow.
> 
> The tube can be calibrated beforehand by measuring  the time it takes for a
> certain amount of fuel to flow thru the tube. Appropriate markings can be
> added to the outside of the tube.
> 
> Anyone have ideas about what kind of tubing to use and what to use for the
> ball?
> 
> SJ
> 85 Dodge PU, D-250, 318, auto
> 85 Audi 4k - - sold but still on the road
> 88 Audi 5kq
> 90 Audi 100q
> 
> 
> 
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