[T3] Marigold's story

[Dennis Stiefel]

Subject: [T3] Marigold's story

Those of you who made the Invasion met Sarah there and know about her car's
problems, but some of you asked for a review of what was wrong and what we
did. I wrote this up from memory, so I'm sure I've gotten some things out of
order and probably left some details out. 
Hopefully, I've managed to include all the important parts.

Here's what happened:

Sarah bought her yellow '71 Squareback, Marigold, out of Washington state
about a year ago. When she got the car, she had it worked over in Ohio,
where she grew up and her parents still live. Since then, she's been living
in Brooklyn, NY and driving Marigold to work almost daily. She had made a
few trips back to Ohio in the past year and felt that the engine was working
normally. This trip was different.

On her way here, Marigold began to bog down and eventually would not go over
30 mi/hr. Sarah called John J. Thursday evening and explained that she had
pulled spark plug wires one at a time and found that # 1 & 3 did not seem to
be doing anything.We agreed that she should try to get to Watkins Glen where
we would meet her Friday morning and figure out what the problem was.

After the drive around the track, we met Sarah and proceeded to look
Marigold over. There were no obvious broken wires and everything looked
pretty normal after a quick visual inspection. I got out my Bosch FI tester
and ran thru the usual tests and found that one of the wires to the intake
temp sensor was broken. So that got fixed. 
The FI plug to the distributor also seemed loose, so I pulled those pins and
tightened them. One of those wires was down to just a few strands, so I
replaced that terminal.

In the course of those tests we ran the starter with the brain disconnected.
To my surprise, the engine started and ran for 10-20 seconds. This indicated
that there was excess fuel still sitting in the cylinders, so it seemed
clear that the poor running had been caused by excessive richness, which the
broken wire would have caused. I assumed the broken wire was the problem and
we started back to the host motel.

Partway to the motel, Marigold bogged down again and could no longer keep
up. We stopped and I replaced the #1 spark plug, which was WAY carboned up,
with a used one which I had bead blasted and brought along as a spare. That
got us back to the motel, but there was clearly another problem. After
inspecting the plugs again, I replaced both #1 and #3, again with used,
blasted plugs. Then we checked the dwell and timing and found the timing
retarded, so we corrected that. 
That seemed like an improvement, but when I mentioned the broken wire to
Keith, he said that that would have made it run rich, but not THAT rich.
That got me worrying again.

I spent the night trying to think of what else could be wrong. By Saturday
morning, I was ready to check the pressure sensor for a broken diaphram.
Indeed, it was. So we spent some time looking for a kluge or replacement.
Dave P. brought in some supplies that I hoped would provide a way to make
Sarah's sensor temporarily functional, but Lyndon saved the day when he came
up with the exact proper part. 
We installed it and thought we were done.

Sunday morning we went at it again, since some test driving still showed
poor running and a lack of decent power under certain conditions. So I went
thru the Bosch FI tester sequence again. This time I noticed that the
trigger point dwells weren't symmetric, so I pulled the distributor to look
at those points. I found worn rubbing blocks running on a rather rough, dry
(no lubrication) cam. I cleaned up the cam as best I could under the
circumstances and applied Bosch cam grease. I applied a bit of motor oil to
the dry trigger point pivots and tried to work it in. At that point it
became obvious that these pivots were so sticky that they were not closing
properly. So I swapped in a spare that I had brought with me.

We re-installed the distributor with the "new" trigger points and re-timed
the engine. Then we paid attention to the pressure gauge that I had
installed on the fuel line for the earlier tests. The pressure was somewhat
low, about 26 psi, so I cranked that up to 30, but the more disturbing
problem was that the gauge needle was vibrating over a range of about 5 psi
and there was an odd vibrating noise coming from the fuel line itself.
Normally that reading is steady.

I decided to check all the injector pins to make sure they were tight
enough. All the terminals on #3 & 4 injectors turned out to have been
replaced with non-locking terminals, so I replaced all 4 of those, and when
reinstalling them it became clear that they had been plugged into the wrong
injectors. The #1 & 2 pins were a bit loose, so I tightend all of them.

Thinking we were done, I decided to re-route some hoses to neaten up the
engine compartment and tried to remove the hose between the AAR and the
Intake Air Distributor. That hose shattered into 4 pieces when I tried to
remove it. The 5/16" fuel hose I had with me was too small to replace it, so
Dave drove home and came back with some 3/8" 
hose that worked perfectly.

The odd fuel pressure readings and vibrations had me worried about the fuel
filter, so we jacked up the front end and I pulled the hose off the output
end of the odd aftermarket filter that I found there. 
Out came a bit of a trickle, rather than the gusher that should have been
there. So I plugged that end and pulled the hose off the inlet side of the
filter. THERE we had a gusher, so the filter screen in the tank was okay,
but we replaced the aftermarket filter with a good used Bosch.

Replacing the filter quieted down the pump, settled down the pressure gauge
needle, and eliminated the "vibration" coming from the fuel lines. I'm
guessing that the pump was struggling to pull enough fuel from the filter,
so the suction the pump created was pulling in air bubbles which were yet
another problem on top of insufficient fuel. 
After replacing the filter, we had to readjust the fuel pressure back to 30
psi.

We installed my overflow hose and vent kits and while the trunk was open, we
removed the gas gauge sender, just so we could look into the tank and see
what was in there. The tank looked clean, with only a small amount of dirt
and no sign of water.

Finally, to cover all the bases, I replaced all 4 spark plugs with a set of
new Bosch WR8AP (Platinum) that I had. I was hoping these would not foul as
quickly, in case we still had undiscovered problems. The idle seemed low, so
we boosted it up a bit, then we took a long test drive. Marigold drove well
and no longer put out black smoke on full throttle. But after the shakedown
the idle was high again and we moved it back down. Everything seemed good,
but we were all still concerned that the problem would return after about an
hour of driving, as it had each time before. By then it was getting late on
Sunday and Sarah agreed to try her luck and head back to Brooklyn.

She made it and now reports that things seem good except for some difficulty
starting and in the first few minutes of running. I suspect that she needs
my primer kit, to run the pump and clear air out of the fuel line after a
hot shutdown. Her Aux. Air Regulator may also be sticking, which would make
a cold start hard to keep going.

I think she's nearly done; Sarah will be able to do those things that may
still need to be done.

Sarah asked which of the fixes we did was the important one. I have to say
that Marigold had several problems which were major. Here's how I rank the
problems we found:

Major: pressure sensor, trigger points, fuel filter

Medium: injector pins, broken overflow hose

Minor: broken temp sensor wire, frayed wire on trigger point connector
(would become major)

Note that the pressure sensor and broken temp sensor wire would have made
the system run rich, but the low fuel pressure and clogged fuel filter would
have pushed things lean. It's likely that the engine ran correctly under
some circumstances, but I suspect that it was running extremely rich in
downtown driving, which is where it spent most of its running time.

The only one of these problems which could have gone on forever without
becoming a big problem was the first one we found: the broken wire on the
temperature sensor. This turned out to be a red herring because it was easy
to find, and I got distracted and assumed 
everything would be fine once it was fixed.   



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

I'll have to save this email for a troubleshooting check list. Great job!  I
didn't know Bosch made platinum for our cars.  I had been told for years all
the way back when they first came out that they would only work in modern
cars with electronic ignition. That old point ignition systems didn't have
enough power to fire platinum properly.  Learn something new.

Dennis Stiefel
72 Fastback FI MT
71 STD. Beetle
67 Ford F-100 (hart of Crown Vic)
Rainsville, AL