Triumph Repair: Triumph TR6 stalls, fuel pressure gauge, bright sunny day

Question
HI, I know there could be a million reasons for this but here goes - My 1975 TR6 runs great....for minutes at a time.  It starts and runs great for a few blocks, then just stalls, kicks, and backfires...runs like that for a few minutes and then runs great again.  Sometimes too it runs well then I pull to s stop sign and then stalls out.  After I play with getting it going again, (keep the revs high and buck for a while) it goes again.  I'd love to be able to take the car more then a few blocks from my house ;)  Any ideas?  Electrical?  Fuel?

Answer
Hi Marc,
The intermittent problem is the hardest problem to fix on a car because it may not be failing when you are testing. In dealerships I have run into these and the only way I could catch the fault was to be monitoring at the time of failure. This is not as difficult as it sounds. All you need is a timing light and a fuel pressure gauge with a long hose and a "T" to put in the fuel line close to the carburetors.

First put the timing light on the coil wire (not a plug wire) and run the wires out form under the hood and put the timing light under a wiper arm so you can see the flash of the light when driving. Tape the trigger down so it flashes all the time and if it is a bright sunny day you will need to tape a piece of cardboard over the light so you can see the flash.
Then connect a "T" to the fuel line just at the carburetors and run a long hose out form under the hood and place the fuel pressure gauge under the other wiper arm so you can watch fuel pressure. (Be sure to put clamps at all hose joints)

Then drive the car until it falters and watch the flash and the gauge. This will tell you if it is Ignition related or a fuel supply problem. It can't spot carburetor or plug problems but those are less likely anyway.

If that don't show you which is failing you may need to find a shop with a scope to watch all components of the ignition system.
Howard