Toyota 1.4 ZZ-FE engine will not start.

Are you sure it's actually a plug?
Are you getting oil on the plug?
The plug may be firing but you may be losing compression which gives the symptoms of a misfire. As you've changed the plug, lead and coil this points to to a problem elsewhere.

Your first course of action should be to get a mobile mechanic carry out a diagnostic check for you.

To put your mind at rest, do a 2nd compression test using a light oil squirted into the bores:

Doing a Compression Test
Warm the engine. Remove all the spark plugs.
Get a pencil and piece of paper to note down the readings.
Put the compression tester into the No1 cylinder and crank the engine for 10 seconds.
Note down the compression reading.
Repeat process for all cylinders.

Here's an illustration of what you may expect on a 4 cylinder engine:
Cylinder 1 2 3 4
psi 125 122 120 124

125 is the uppermost figure for that engine. Here, this engine is fine. There's a slight variation in psi figures, but that's perfectly normal.

Here's the same engine:
Cylinder 1 2 3 4
psi 110 112 114 112

The psi reading is down. However, as all the figures are pretty much equal it doesn't indicate head /gasket problems. It may point towards worn pistons or burnt valves.

Now consider these psi readings:
Cylinder 1 2 3 4
psi 125 84 86 124

There's more than a 10% drop - a difference - between cylinder 1 and 2, and cylinders 3 and 4.
The compression readings for cylinders 2 and 3 is down; low. There's something clearly wrong.

It suggests that there is a defective head gasket between cylinders 2 and 3 or a crack in the cylinder head. The rising piston compresses the gases which escape into the adjoining cylinder via the defective gasket or cracked head.

However, it could also mean that there is a problem with the valves (burnt/not seating properly) or perhaps piston / ring problems.

A burnt valve - it's usually the exhaust valve as they bear the brunt of the combustion - can cause a reduction in engine power simply because the combustion process isn't occurring properly. Compressed air/fuel gets squeezed out of that cylinder because of the damaged valve . There even may be a misfire - a surge as the car runs.

Worn or broken piston rings allow compressed gases to leak past into the crankcase. A compressed crankcase can force oil out of the dipstick tube. The pressure in the crankcase will leak to atmosphere anywhere it can find an outlet.

The 2nd Compression Test
The second compression test is known as a 'wet test'. The first compression test was the dry test because no oil was added to the bores. The second 'wet' test can give an indication of whether it is the rings or valves at fault (though bear in mind rings and valves do not cause overheating or water in the coolant symptoms).

Spray a liberal amount of light penetrating oil into each cylinder - aim for the cylinder walls, not the centre of the piston. You want the oil to run down the cylinder wall and around the piston to form a seal.

Place a rag over each spark plug hole and spin the engine to eject the surplus oil.

Then carry out a full compression test noting down the results.

Here's the previous results with the 2nd compression readings added:
Cylinder 1 2 3 4
psi 125 84 86 124
Wet 128 112 110 126

The readings have increased. This because the oil sprayed into the bores has formed a temporary seal around the piston, thereby enabling the compression to be raised. It also indicates that the bores/rings are worn on cylinder 2 and 3 - the 'oil seal' has increased the readings but is still low in comparison with cylinders 1 and 2.

This could also indicate that in addition to worn rings there is also burnt valves. Oil cannot form a seal around a valve. A worn or split valve will cause a low compression reading and misfiring symptoms.
Compressions readings should be taken in conjunction with other symptoms. It will help you identify the problem:

Low compression readings between two adjoining cylinders point towards a head gasket/head fault if your vehicle has shown signs of coolant loss, coolant in the oil system - mayonnaise, overheating, rough running and lack of power.

If those symptoms are not present it points towards burnt valves/piston rings. A worn engine may be difficult to start and pressurise the crankcase, but it doesn't cause overheating problems.

A D-50 with a carb - that is a few years old and probably lots of miles on it.
If you know you has gas and spark to the plugs then either there is not enough compression (engine worn out) or the timing of spark to compression stroke of the engine is wrong.
Make sure the timing belt is ok
Then check compression - the lowest cylinder should not be less than half of the PSI of the highest cylinder and they should be about 125 PSI or more. If it is down as far as 100 PSI it may still run but is very weak. Be aware also that Compression guages can vary significantly in their readings.
While you are checking cylinder #1 - check to see if the distributor lines up to #1 tower on the cap while the compression stroke pushes air out.
Let me know if this helps you at all

A new engine would be about 180 psi for each cylinder. As the miles add up and wear occurs, compression will get lower. The important thing is that compression is even and balanced-lowest compression reading should be within 75% of the highest cylinder's compression. Some Toyota engines had a minimum allowable compression of about 135 psi, but if compression is balanced, you could have average compression as low as 125 psi and engine would still run good, some loss of power but still acceptable, and oil consumption would not be that bad.
If cylinder compression is below 120 psi as an average, you should be looking into a rebuild event-rings and valves need attention. If any cylinder is below 100 psi, it may not even fire, certainly will produce no power, and could be a head gasket failure, very worn rings, or valve problems.
Remember the important thing is to find compression readings that are very close to each other. I have an '87 Sentra with 75,000 miles(true!)-lowest comp. is 160, highest is 165 psi-runs great, good power. Also a '79 Datsun pickup (with god only knows how many miles-about 200,000 maybe). Compression is about 125-135 psi, fairly well balanced-noticeable loss of power, very little oil burning, still runs fair to good-dependable, at least.
That should give you an idea of what to look for. Good luck.

If cylinder compression is too low, the car may not even start because of it. Have a shop do a compression test or a leak-down test to check the internal health of your engine. A good engine should have pressures of 150-200 psi in all cylinders and be close to each other. A worn or high mileage engine may have pressure as low as, say 125 psi, but if still balanced (close readings), would still run decent. Compression below that, especially below 100 psi, is serious trouble. ignition spark refuses to ignite the air/fuel mixture and you get a misfire-a non-working cylinder. Low compression can be caused by worn piiston rings or poor valve sealing. Low compression in 1 or 2 cylinders can be a valve problem, burned valves or valves not seating properly.
A leak-down test will check each cylinder and if there is a problem, the test will find the cause of the problem.

all 4 cylinders are at 50 psi?did you remove all of the spark plugs to do a compression test?do you have a quality compression gauge ?do you have the right fitting installed in the spark plug hole, and is it tight?
if so. your next step is to preform a cylinder leak down test. you will need an air compressor to so so.one of the best things about your toyota is that it is a non interference engine. which means if the timing belt jumped, you wont damage any valves. be sure to check you timing marks before you decide to just junk the car.you could have some bad valves, or just need new rings!definetly keep searching before you junk the car!start by checking the timing, and then do the leak down test.

You need to find out where you are leaking fluid at. Check all your hoses and clamps. Make sure it is not leaking there. It may be from inside the engine. The engine has to have coolant at all times or it is going to cause damage.

The signs for a blown head gasket are:
1 - The car oveheats above 195F.
2 - The cooling system is loosing coolant, low coolant level.
3 - The coolant start boiling and owerfloing from the coolant bootle.
4 - Mixture of coolant in oil, or oil in coolant.
5 - White smoke from the tail pipe.
The diagnoses to reveal a blown gasket are.
1 - Radiator compression test. Can be done at any car reapair shop for $30.
2 - Static cylinder compression test. Can reveal at which cylinder is the blown gasket (pression low, or zero). This is very important at V6 or V8 engines.

Your timing chain has jumped a tooth or three. Replace the timing chain.

Yea, because what probaly happened is that, you dropped a cylinder or two...which means you probaly have bent valves..that's why your compression is way out of wack...I believe that engine is an interference engine..so when the timing became off, the piston hit the valves..and bent them...You can take the heads off and have a machine shop, or you, can put new valves in it...Good Luck