[T3] B brain

Jim Adney jadney at vwtype3.org
Sat Jun 9 07:33:06 PDT 2018

On 8 Jun 2018 at 10:29, Mark Reno wrote:

> I have done the trouble shooting that is in the book. And have pulled the
> injectors and have watched them spray. I replaced the pump when I got the
> car because it wasnTMt working. I have also already done the tune up
> stuff and checked my timing multiple times. And when I have held the plug
> wires to a ground I get a dim spark. I also tried a different regular. I
> could have over charged the system to. The book says that could  ruin the
> system.

If the pump runs for ~1 second after you turn the key ON, you know the 
power and ground for the brain is all good and that the portion of the brain 
that monitors the engine rpm and controls the pump is all good. This also 
tells you that the FI wiring to the starter solenoid is correct.

If the pump comes on and stays on, after turning the key ON, the FI wire to 
the solenoid is on the wrong terminal. If so, disconnect that wire and leave it 
where it can't touch anything, other than possibly a ground.

If you can see the injectors pulse gas while cranking the engine, you've 
verified that the injection control portion of the brain is working. That leaves 
the brain as confirmed good. The problem is elsewhere.

The fact that you see fuel injection squirts also verifies that the trigger points 
are working properly.

If you've checked the dwell and timing and it's always been good, then the 
distributor is correctly seated and the injection pulses are timed right.

Other things to check:

Verify that the hose between the IAD and the pressure sensor is connected 
at BOTH ends.

Loosen and then tighten the ground screws for the injector ground wires on 
each head.

Verify that the plastic parts that hold the injectors are intact, so that each 
injector is held firmly against its port in the intake manifold. There should be 
no play between the injector and the intake manifold.  

Pull the spark plugs and make sure they are in decent condition, not sooted 

One other thing I can think of is that sometimes the FI will flood the engine 
and this can be hard to get around. To fix this, make sure the battery is well 
charged, then, with your left hand, reach under the dash and find the white 
connector on the face of the fuel pump relay. Pull that connector off JUST 
FAR ENOUGH that you can push it back on quickly and easily. I pull it back 
and then tilt it just enough that one prong is still connected, which keeps the 
connector aligned just enough that it can be pushed back on. Practice this 
move. Then pull the plug back and turn the key to START and try to start the 
engine. Use the gas pedal to give it more air, but don't pump the pedal.

Crank for some time. If it was flooded, it may start to fire and eventually sort 
of run. Keep cranking until it JUST shows signs of starting to run less well, 
then plug the fuel pump plug back in. Use the pedal to keep it running. You 
may have to repeat this. Your timing with the plug is critical. If you plug it 
back in too soon, it may flood again. If you're too slow, it won't start and you 
may have run the battery down too far.

Try not to run the starter more than 1 minute at a time. Let it cool down 
between tries.

If this is your problem, I have a $30 switch kit that will let you easily turn the 
pump on or off to get around this problem.

Report back with what you've found. Let us know your location.

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

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