Triumph Repair: TR6 PI, fuel pressure gauge, hose clamps

Question
QUESTION: Morning Howard.

I have been experiencing difficulties with my TR6 after travling 4,5miles and the engine is warm.

The car starts to miss backfire etc and eventualy grinds to a stop. This is acompanied by the engine over revving (as if the choke had been pulled on) I suspected the coil and have already replaced that with no affect. can you sujest whe the problem lyies nd how to correct?

ANSWER: Hi Bill,
Your symptoms do not pinpoint what the problem is but as with all engines for an engine to start misfiring and backfiring and then quit. One of the basic three necessary items is missing. All engines only need three items to run, compression, fire and fuel with conditions on each.
Compression will not usually come and go like that so you can look at fire and fuel. Do not replace any more parts until you know what is wrong as you may run out of money before you find the cause.
You need a method of seeing fire and fuel at the time of failure. To do this you need a couple of tools. A fuel pressure gauge with a extra hose, some clamps and a fuel hose "T". Also you need a timing light.
These are not expensive tools and they will be useful on any most any older car.
First remove the fuel line from the carburetor and install the "T" fitting into the line and put a short piece of hose from the "T" to the carb and run a long piece of hose from the "T" to the gauge. Then place the gauge under a wiper arm so you can see the gauge while driving. Be sure to put hose clamps on all joints.
Then tape the trigger down of the timing light and connect the timing light to the COIL wire and run the leads out from under the hood and put the timing light under the other wiper arm so you can see the steady flash of the light. (if it is a bright sunny day you may have to tape a piece of cardboard like a hood over the end of the light so you can still see the flash in the bright sunlight.
Now drive the car until it fails and quickly look at the gauge and light to see if either fail before the engine stops rotating.
Even a miss will show up in the flash of the timing light and the fuel gauge will tell if it is a fuel supply problem.
You can duplicate this in a shop by putting a strong fan in front of the radiator and set the RPM at or a little over 1500 RPM and watch the timing light and fuel pressure gauge. You should see from 1.5 to 3 PSI on the gauge at all times.
Howard

---------- FOLLOW-UP ----------

QUESTION: Afternoon Howard,

Will this method of fault diagnosis work on injected cars as well as those fitted with carburetors?

Bill

Answer
Hi Bill,
Yes, except the injected TR-6 (often called a TR-5) here. uses a high pressure, so you will need a gauge that spans 0 to 120 PSI and the system pressure will be 100 to 110 PSI checked with a "T" placed at the fuel line as it enters the fuel distributor.

This will only test fuel delivery to the fuel distributor at the time of failure but that is one thing you need to know when diagnosing an engine dying.
Howard