Subject: [TR] TR6 Electrical Issues

From: William Brewer <[email-masked]>
Date: Fri, 13 Sep 2013 08:13:29 -0700 (PDT)

My 1974 TR6 has not really be driven since the mid-80's sometime, maybe
even earlier.I have logged about 15 miles in 1 block test drives over the last
5 years.  It just put in a new front clip of the inner left fenderwell and
front valence and the bodywork is bolted back together. Before this project
(about three weeks ago) I took the car for a test drive without fenders and
hood. Now that I want to go for a test drive with the assembled car, the car
won't start. It started up the first try and then stopped when I discovered
that it was out of gas. I put in gas and then it cranked briefly and slowly. I
assumed that it was a dead battery, but the battery had been charged recently.
I heard what sounded like the starter solenoid clicking.
     When I hook up
the battery, something clinks under the hood like it is energized with the key
off. I checked it out and found that on the right side of the radiator are two
cylindrical things. The top (big) one has hoses going into it (carbon
cannister?) and the smaller bottom one has two wires attached to it. The
bottom one appears to be what is clicking when the battery is hooked up. Can
someone tell me what this thing is?
      I previously had problems with the
ignition key and it wouldn't turn or come out of the ignition. A little WD-40
and working it and it eventually turned. It is the original key. You have to
joggle the key in the start position to get the car to start, like it has a
bad contact.
     I am still trying to figure out what I have for a car and
need to drive and test it.
     TR6 electrical is a lot more complicated than
my TR3.
     I am assuming that perhaps my starter solenoid is burned out.
   
 Any advice would be appreciated.

     Bill Brewer
     Tehachapi, CA

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From: "Randall" <[email-masked]>
Date: Fri, 13 Sep 2013 10:04:02 -0700

> I checked it out and found that on the right side of the 
> radiator are two

That would be the anti-runon valve.  It is supposed to be energized only when the key is off and the engine still has oil pressure.
Sounds like your oil pressure switch is wired wrong.  For now, just pull a wire off the solenoid.

>      I am assuming that perhaps my starter solenoid is burned out.

Could be, but doesn't seem likely from your description.  Try momentarily running a jumper from the hot side of the batter to the
side terminal on the solenoid (the one that should have a white/red wire on it) and see what happens.  If the engine cranks, the
problem is not the solenoid.  If not, use a voltmeter to check first that you are actually getting 12v from the side terminal to the
solenoid housing; and then check the voltage across the two big terminals on the solenoid.  If it has juice coming in, but there is
12v between the two big terminals _then_ the solenoid is bad.

Randall

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From: [email-masked]
Date: Fri, 13 Sep 2013 13:32:59 -0400 (EDT)

That little round thing with the two wires going to it is the Anti-Run-On 
valve.  It works in concert with the three prong oil pressure switch and a 
special contact on the keyswitch to energize when shutting down.  It applies 
manifold vacuum to the charcoal canisters and hence to the top side of the 
float chambers in the carburetors to starve the engine of gasoline to prevent 
run-on.  It should not be clicking in the situation you describe.  Since you 
have had problems with the keyswitch I would look there first.  If this 
stays energized all the time the engine will start but will not continue to run 
very well.  But it will not prevent it from starting.

If your battery is fully charged but cranks slowly there are a couple 
things to check.  Check the battery ground connection.  On the TR6 the negative 
cable has two tabs, one of which attached to the body at the firewall and the 
other attaches to the engine/bell housing flange.  Make sure that 
connection is solid.  Also check the positive cable connections at both ends.

If you engage the starter with the lights on do they dim?  If they dim then 
you may need a new starter.  If they do not it could be the solenoid.

The next step is to dust off the multimeter.  Measure the voltage between 
the engine block and battery negative when cranking.  It should not exceed .5 
volts.  Measure the voltage from the starter stud and the battery positive 
post.  It should not exceed .5 volts.  Knowing this will help narrow down 
the search.

Good luck.

Dave