[T3] 69 FI trouble shooting

[Jim Adney]

You've covered all the bases, so that leaves very little to look at.

I would go back and verify that the valves are adjusted.

Was there a gauge on the fuel pressure while the engine was dying? If 
so, was the pressure holding at 29 right up to the end?

Check the system voltage when the engine is running. If you can get 
it to a mid rpm, it should go above 14 V measured at the D+ terminal 
on the generator.

If all that is okay, how about sending me the trigger points to re-
set? That's about all that's left that I can think of.

On 18 Jul 2012 at 23:15, R. David wrote:

> Steve Crispino has been working on getting his 69 Automatic Fastback put
> back to FI from a carb conversion. He has received some help from the list
> here and has made great progress getting it running....however it still has
> a running issue, so I tried to help him out with it tonight.
> 
> This car has early FI system on it with the "B" FI parts, a 2 plug TPS and
> it has the pressure switch setup. The car started right up, seemed to run a
> normal slightly rich condition until a few minutes of warming up - then
> smoothed right out nicely. Dwell @ 46, timing right on zero, idle speed
> easily adjustable for timing. Brought idle speed back up to 950, idling real
> nice. It didn't want to quickly respond to accelerate (under a no load
> condition), and it almost seemed to respond as poorly if I unplugged the
> pressure switch or not. (The pressure switch is confirmed to electrically
> trip once suction is applied, and Steve ran new wires back to the brain for
> it to make sure it's connected to the brain.) I sat in the drivers seat to
> put it in gear and power brake it to see how responsive the motor was under
> a load.... and it was not! Once I did this the motor started a slow death
> spiral that could not be saved. I went back to the motor to feather the
> throttle by hand to keep it going but it kept slowly loosing power and speed
> until it stalled. It would crank after that, but no fire. This only took
> about a minute to die once it started to loose power.
> 
> After this; just by cranking it we still had a dwell reading, and the timing
> light confirmed each plug was getting a spark. Spraying a flammable spray
> into the IAD got it to fire up for a few seconds, but once the spray was
> used up there was no more fire.....so it appears to not be getting fuel at
> this point. Steve says that once this motor cools back down again; it will
> fire back up and run until it gets warm again......then the same thing
> happens. He has a constant 29 psi of fuel pressure. We did a ohm reading on
> both temp. sensors when cold and when hot and they both are reading correct.
> He did a ohm test reading on the pressure sensor and it is showing correct.
> Trigger points look good and clean, although he cleaned them off with a
> business card to be sure. TPS is adjusted properly and I could hear it
> function correctly when I operated the throttle by hand. AAR seemed to be
> working good when it was running. Steve says the valves are adjusted
> correctly, and the compression runs around 140 or so except for #3, which is
> down to about 110-120. Steve just put in new jugs, and he said the heads
> looked great so he re-used them as-is for now.
> 
> At this point Steve has no other brain or pressure sensor to swap out and
> see if it matters.
> I think it has a bad brain in the car, but without spare to swap out; we
> can't try it.
> 
> Thoughts or suggestions?
> 
> Dave Pallo
> '72 Square ~ "Elwood"
> Fairport, NY
> 
> 
> 
> 
> 
> 
> 
> 
> 
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-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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