Re: [T3] Erratic driving behavior #2

[Jim Adney <jadney@vwtype3.org>]

On 23 Oct 2005 at 23:09, shalom@ucla.edu wrote:

> My 70' squarback will drive for awhile and then out of no where it will just
> die, like it doesn't have any fuel, or the mixture is to rich/lean.  Then I
> can't restart it for a random amount of time.

Does it die suddenly, or with some warning? ie, does it cut off abruptly or 
slowly weaken or start to misfire?

When it won't start, do you still hear the usual series of relay clicks when 
you turn the key ON? Can you hear the fuel pump run for about 1 second right 
after you turn the key ON?

Once you have this failure, does it always restart if it is left long enough to 
cool down completely?  

> I checked the fuel pressure and it was correct at 29psi.  I check the Manifold
> pressure sensor which was fine too.  I checked both Temp sensors, they're fine.

Did you do these checks during a time when it wouldn't start?

> I should probably pull the injectors out at some point and check the spray.

You can do a reasonably good test by just putting on your pressure gauge, 
getting the pressure up to 20 and then depressing the throttle with the key on.
You should be able to hear the injectors clicking and watch the pressure drop 
when this happens. This tells you that gas is exiting the system, which is a 
good sign that the injectors are working.

This problem does not sound like injectors anyway, because they don't tend to 
cure themselves after a rest.

> What about the throttle valve switch?

It wouldn't cause this problem, but you can just unplug it as a test. The car 
will run okay without it. If this doesn't have any effect on your problem, then 
this is not the cause.

> What about the cold start system? 

The CSS only works while starting in cold weather. Yours is probably doing 
nothing. As above, you can just unplug the CSV as a test.

> The Oil pressure sensor is also something that I haven't been able to find
> numerical information about.

That switch only turns on the oil light on the dash. There's no connection to 
the FI system. It's just a switch: on or off.

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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