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Re: FI pressure drop

On  6 Jul 98 at 11:55, type3@vwtype3.org wrote:

> I'm yanking the  FI motor and system out of Deathrust tonight, and ran
> the engine for the last time in tits own car.  While I was going through
> my starting ritual, I realized that I had no clue why I had a starting
> ritual.  hense my question,
> '71, 70K miles, all stock,New hoses, checked the injectors, all seem
> good.  When I start the car, I have to turn the key on and off 6-7 times
> to build up pressure.  After about 5-6 days, I would have to do the
> whole thing over again (although within 1 day, all is cool)

I have seen, and had, several cars with similar problems.  I have 
assumed that the problem arose with the "heat soak" that occurs after 
shutdown.  This vapourizes fuel in the lines and either pushes 
fuel/vapour out somewhere or forces gas back or forward into the gas 
tank.  When the engine compartment cools later the vapour in the 
lines condenses and creates a vacuum in the lines, causing air to be 
drawn in.  Thus on restart, the lines are empty and require 
significant priming before the engine will start.

I have successfully bypassed, but not fixed, this problem by 
installing a momentary contact switch around the fuel pump relay that 
allows me to prime the fuel system without wasting the battery by 
cranking the starter at the same time.  It works every time and I can 
hear the air bubbles coming out of the gas line into the tank in 

My system is wired so that I get into the car, turn ON the key, hold 
the button in until the bubbles stop, and then release the button and 
start the engine in the usual way.  I have replaced or swapped many 
things on these cars, but still don't have proof of exactly where the 
leak is.  I suspect the injectors.

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

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