'70 T No Start Condition

BlueSideUp · 03-06-2007, 08:05 AM

I spent the last couple of weeks refinishing my wheels so the car was up on jackstands for a while. After all that time the batteries needed charging so I removed them from the car and charged them up. I also replaced the brake lines all around, installed a new cap, new rotor, cleaned the points, and replaced the driver's side heater hose.

Once the car was on the ground I turned the key, let the fuel pump pressurize the fuel system for a few seconds and it would crank but only barely fired once. There was no popping from the exhaust like the plug wires were installed on the cap incorrectly (I verified the wires anyway). I can hear the fuel pump running and smell fuel at the exhaust pipe. I can hear the CD box whining.

I reinstalled the old cap and rotor but it didn't make a difference. I checked the fuses in the engine compartment and they are fine. All of the wires seem to be connected.

The pain in the butt about this is that the car ran great and fired right up before going up on jack stands. Right now I am on a trip and won't be home until Friday to diagnose. My guess is that I knocked off a wire, perhaps a ground? Should I just buy a new coil to have on hand or do they not just die like this?

BTW the car has the stock CD ignition with a Bosch distributor and Webers.

Thank you guys for your help.

BlueSideUp · 03-09-2007, 05:25 AM

It turns out I slightly bent the arm for the points when cleaning. I decided to take a fresh look at the problem and noticed the arm right away. During cranking the tach flipped all the way to redline once which also indicated a problem with the points.

Car runs great now!

BlueSideUp · 03-09-2007, 11:16 AM

Grrr I spoke too soon. It won't start again. Hmm, I cleaned up the grounds at the driver's side forward engine compartment. I checked the ground from engine to chassis and it checks OK, checked the coil ground and it's OK, tried two different caps, two different rotors. Checked the points....and noticed they are different from the ones sent to me for a 1970 911T.

And found out I may have an engine out of a 1972 911 in my 1970 car. I will check the engine number in a bit. It's on the bottom of the case right?

Grady Clay · 03-09-2007, 11:35 AM

I really suspect the no-start issue is the points. Check the clearance when open and confirm they close. On some distributors there is a little braided ground from the points plate to the housing – check that you didn’t brake that.

A good way to check the system is to position the coil wire near a ground with a small gap. Take the points wire off the distributor and touch it to ground. You should get a spark between the coil wire and the ground. Reconnect the points wire and have someone crank the engine. You should get sparks at the coil wire. If not the points aren’t operating correctly.

The engine number is just to the right of the fan, facing to the left. It is on the part of the right crankcase that supports the fan housing. There is also a Type Number stamped vertically in the case just forward and to the right of the engine number. These two numbers will tell what the engine was originally.

Best,
Grady

BlueSideUp · 03-09-2007, 11:46 AM

OK disregard. My fan strap says emissions compliance for 1972 model year but the engine number is 6105243. So it's clearly a 1970 motor.

I'm basically not getting any ignition whatsoever.

First a pic of the distributor with cap installed.

Now a pic with the cap off. There was a problem where the rotor scraped the cap because it was on crooked. That's why you see the rub on the rotor and the orange shavings in the distributor.

Here are the points which really don't look like the points sent to me for a 1970 911 T.

Cornpanzer · 03-09-2007, 11:59 AM

Go to Autozone and buy a cheap $10 VW Beetle coil. Hook up the coil and I bet she starts. (Not saying to run this coil, its just a cheap diagnosis tool)

I have had two coils fail on me and both created enough intermittent spark to cause me to rule out the coil as the problem at first..

BlueSideUp · 03-09-2007, 12:10 PM

Thank you very much for the help Grady. I grounded the points and have spark from the coil. Then I checked spark at the coil while my wife cranked the engine. Then I put a spark plug in the #1 plug boot and have spark there. So it seems my ignition is working fine.

I must be having a fuel problem, I checked for anything weird stuck in the intake or exhaust and they are clear.

OK I just changed the fuel filter and there doesn't seem to be any fuel in the line from the tank. The new filter is clear on the pump side and I don't see any fuel coming in filling it up. I can hear the pump running up front.

BlueSideUp · 03-09-2007, 12:14 PM

Disregard that statement. I have plenty of fuel coming out of the fuel line going into the filter. I'll try to diagnose to make sure I have fuel coming out of the carbs a little later.

Grady Clay · 03-09-2007, 12:49 PM

Do not run your CDI through any other "coil" than the Bosch
ignition transformer. They are not the same. Yes, you can
use a standard Kettering ignition system (ballast resistor,
condencer, points, coil) as a diagnostic tool. You don't have
a condencer on the distributor.

Great pictures!

The distributor clamp (green arrow) tells us that this is a ’71
and earlier crankcase.

The black/violet wire (yellow arrow) goes to the tach.

The larger black wire (red arrow) goes in the harness to the
CDI. It is possible there is a problem there. I recall that as
a shielded wire. I would remove the fast-on connector and
inspect the wire inside.

Please confirm the two other wires (blue arrows) are brown
and blue/yellow and go to the ignition transformer (“coil”).

OK, on to the points:

I still suspect the points are't electrically opening and closing.

The rubbing block (green arrow) is on the flat between the two
distributor cam lobes (red arrows). The points (yellow arrow)
should be closed. Check with an ohmmeter.

Using the crankshaft pulley nut, rotate the engine clockwise (CW)
about 60° until the rubbing block (green arrow) is on the peak of
a distributor cam lobe (red arrow). You can finesse this
somewhat with the advance mechanism. Now you should have
points gap of about 0.016” corresponding to specified dwell
angle 38° ± 3°. CDI are not terribly sensitive to points
gap/dwell until the points get close to being closed up.
Check for no contact with an ohmmeter.

The points need to be absolutely clean – no dirt or grease.
Everyone has a preferred cleaning method. I use a cut piece
of cardboard (like a paper match) soaked in alcohol, brake-clean,
etc. and finally a dry one.

Additionally, the distributor cam needs appropriate grease in
VERY limited amount.

I am a proponent of servicing the distributor off the engine and
checking it on an old-time distributor machine.

You should ALWAYS check the ignition timing at 6000 rpm anytime
you tinker with the distributor.

Best,
Grady

Cornpanzer · 03-09-2007, 05:16 PM

Quote:

Originally posted by Grady Clay
Do not run your CDI through any other "coil" than the Bosch
ignition transformer. They are not the same.

Just to be clear, I recommended using a cheap Bosch coil as a test device.....not to operate the car. With all due respect, ten seconds isnt going to hurt the CDI, and I would rather gamble with a $10 part than a $250 part.

Like I said, both of the stock coils that I had fail would still fire a spark plug outside of the combustion chamber, but would not work under compression......so dont rule out ignition problems simply because you can see a spark with the plug out. The extra resistance of compression could be breaking down the ignition.

Tony k · 03-10-2007, 11:35 AM

I noticed you have the tach wire ( black/violet ) connected to the points, I had this on my 71t using cdi box but have found this to be wrong (bad starting tach not working) unless the tach has been modded, theres another thread which I found useful regarding this.
The black/violet wire was connected to the points on pre cdi motors with a condenser

Grady Clay · 03-10-2007, 02:12 PM

Tony,

Welcome to the Forum.

You will find a lot of help here.

One difficulty here is ’69, ’70, ’71 and ’72-’73 all have subtly different wiring and components here concerning tach and MFI.

That is the reason I asked Pelican BlueSideUp to confirm the wire color and where they went.

There is notable difference between a ’70 and ’71 here. How original is your ‘71T? Your black/violet should go from the points, through the 14-pin engine connecter to pin #4 of the 6-pin rectangular socket for a MFI speed-switch (RPM Transducer, not installed) and then through the 14-pin connecter into the main harness. A ’70 has to go through an “Intermediate Unit”/ “Switching SCR” to condition the signal for the ’70 and earlier tach. That device was eliminated starting in ’71.

I have a draft of the circuits for ignition and MFI for each of the four versions - ’69, ’70, ’71 and ’72-’73. It will be in “current flow” diagram format. I appreciate every scrap of info. I don’t think anyone at PAG has complete info.

Best,
Grady