[T3] Fw: 71 sqbk FI question

Jim Adney jadney at vwtype3.org
Tue May 28 11:05:13 PDT 2019

On 28 May 2019 at 16:59, Birtalan, Victor wrote:

> Hello, my name is Vic Birtalan, I drive a 71 squareback that is fuel
> injected and I am attempting to resolve a problem with either fuel flow or
> spark.  The engine starts normally and when up to a cruise speed runs
> fairly well, but is difficult to gain speed when putting a load on the
> engine, as in accelerating.  A mechanic has ruled out most of the usual FI
> problems and has stated that this inability to accelerate may be due to a
> crack in one of the cylinder heads.  He has established that two
> injectors, on opposite sides of the engine, are not receiving fuel when
> the engine is under load.  He speculates that current to the plugs on
> those cylinders is being diverted by the crack.  Has anyone encountered
> this scenario on a 71 FI?

That diagnosis sounds completely bogus. If your mechanic is unable to 
decide whether this is a fuel or spark problem, you need a better mechanic. 
The problem here is that finding a mechanic who still remembers D-jetronic 
FI may be hard to find.

If you would post your location, someone here may be able to recommend a 
better mechanic in your area.

Frankly, my first thought is that the mechanical advance in your distributor 
may be stuck. This is a common problem and easily diagnosed: Remove the 
distributor cap and grab the rotor. It should turn ~15 degrees against spring 
pressure and then snap back smartly when released. There will always be 
some free play in the drive, so ignore that. Any other result, report back here 
and maybe consider sending me your distributor to be rebuilt.   

Another possibility is that your voltage regulator is worn out and regulating at 
too low a voltage. If the voltage is too low, the FI runs rich and the engine 
will have poor power. If you have a voltmeter, put it across the battery 
terminals with the engine running at medium RPM. You should measure 
14.1-14.4 V. If it measures below 13.5 V, you need a new VR. Get a Bosch 
30 019. I stock them if you can't find them locally.  

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

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