Triumph Repair: possible fuel problem continued, vacuum tester, compression gauge

Question
QUESTION: Howard:

Ran the compression test 1-4 as follows; 125, 120, 120, 115.
Thought I'd pass them along be fore I spend more money on a vacuum tester and fuel pressure tester. I have a feeling that those pressures are not to good.

Pat

ANSWER: Hi Pat,

Those readings are not great but don't condemn the engine yet. Run a "Wet" compression test by adding about a teaspoon (several squirts from an oil squirt gun) of engine oil in the plug hole and run a second test (throttle open)

The second test will be higher then the first (dry test) but it should not be much higher. If it is a lot higher (more then 10% to 15%) you have a ring problem.

Also test your compression gauge on a known good car.

Howard

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

QUESTION: Howard, can't thank you enough for your continued support.
I ran a second dry compression test with a differant connection ie. better seal and it came out 130 psi on all 4 cyls.  With this in mind I desided to work on the fuel system. This spitfire has both a oem mechanical pump and what appears to be an after market electric pump. They run parellel with each other. The electic one is wired to a toggle switch on the dash and runs only when the switch is held to the on posission, possibly for the purpose of priming the carb. I disconnected each pump one at a time plugged its line and ran the engine using only one pump at a time. I also installed a inline pressure guage. Each pump produced 6-7 psi. Both the mechanical and electic pump when used seperately made a big differance in how the car ran. It idles normally. I can also pump the accelerator and increase rpms normally 4000-5000 rpm. Unfortunately the engine will not maintain a high rpm. If I don't pump the throttle, and try to just maintain a high rpm the engine will die. I feel like I'm getting close but still no cigar.
Regards, Pat

Answer
6 to 7 PSI will normally make a Stromberg or an SU carburetor flood as the float can't shut the fuel off at that pressure.

Pumping the throttle on a Stromberg or an SU carburetor does absolutely nothing as neither has an accelerator pump.

Stop playing with the throttle to keep it running and spray starter fluid into the intake to keep it running and if you can keep it running by spraying starter fluid into the intake then stop and turn off that extra pump and remove the carburetor or carburetors (what year did you say this was?)

Fuel supply can not be your problem as you have 6 to 7 PSI pressure (which is too much) If starter fluid makes it run then you have a fuel starvation problem in the carburetor or carburetors depending on what year this car is.

Did you do a vacuum test on the intake manifold? If so what was the readings at the time it is dying?

Howard