QuestionI recently rebuilt the Strombergs, installed new plugs and wires and It wont start for me. I have fule pressure and there appears to be fuel behind the carbs. I spray starter fluid into the carbs and still nothing. And the plugs are dry. Its like the fuel isnt getting to the cylinders. Any advice???
AnswerHi Steven,
As a Jaguar mechanic in several dealerships I was faced with that problem as many as several times a week and sometimes several times a day for many years. It was necessary for me to work out a procedure to find the problem with an engine that doesn't start.
All gasoline engines operate the same and they only need three items to start and run. Compression, Fire and fuel. (with conditions on each)
The simplest and first test is to do what you did by spraying starting fluid into the intake and if you get a "No Start", you have eliminated "Fuel" as the cause. Even a very poor engine will start on starting fluid.
Now it is either a mechanical or electrical problem.
At this point I made it a policy to run a compression test (throttle open) and a intake manifold vacuum test (throttle closed) This told me for sure if the engine itself was capable of running.
Some mechanics chose to first run a preliminary "Fire" (spark) test. This is easy to do and does not require any special tools other then hand tools.
Remove one or all spark plugs and put each plug on it's wire and lay that plug or plugs on the engine. Now put your thumb over number one plug hole and have someone spin the engine while you watch number one plug. (not is bright sun light)
As the engine spins it will blow your thumb off of the plug hole with a "Pop" noise. At the same time number one plug should spark with a Blue spark and it should be a thick spark (about the thickness of a pencil lead. The spark will make a "Click" and if you notice, the "Click" seems to have been made by the "Pop" sound. If the two were in order like "Click-Pop" or Pop-Click" then the timing may be off enough for it not to start. If the spark is thin like a hair and yellow or orange in color the spark is weak and may not start either.
This is a preliminary quick test of spark and timing.
I often used this as my third test. I prefer to test the engine before this because it is a waste of time doing anything if the engine is not sound.
The compression test should show 135 to 170 PSI on all cylinders with little difference between cylinders. Vacuum at cranking speed is very much dependent on the setting of the throttle plates of the carburetors so all you are looking for is some vacuum. An important factor if the car has been in storage or not run in a long time, is watch the vacuum as you first start spinning the engine and if the vacuum seems to go way down as you spin the engine, you may need to open the exhaust (I usually opened the pipes at the manifolds) and run the vacuum test again. I have often found stopped up exhaust systems due to rodents in stored cars.
In some of the dealerships I worked in I had access to a scope so I could test the complete ignition system and even get an electronic test of compression with just a few test leads and one good spin of the engine. Most people don't have a scope available and it is nice but not necessary to run tests.
Howard
