TOPIC:

Long story short, engine started sputtering and running terribly rich last spring, found out there was worn out tensioner pulley and it was replaced along with new timing chain.
CDI box was toasted so it was replaced too with used one.
After this the engine does not start. It cranks ok (fuel pump works and primes too) and if i give some throttle it backfires to aircleaner. Tried to turn cams 180 degrees, did not make any difference. T-mark and timing is spot on.
Temperature sensor next to thermostat broke and was replaced with the one from Toyota Hiace.
Need help, we have tried everything.

Crikey Tuomas, why would you turn the cams 180deg, that would put the valves into the piston surely??!

I'd say check that the mechanical timing is 100％ per the manual first,
Then do a compression test on all cylinders and if good,
Then do a spark test (take a plug out and hold against engine / earth with rubber pliers and crank to confirm spark) then,
Do an injector test, can you remove an injector and hang it in a plastic bottle and confirm it sprays when cranking engine?

A simple test also, once mechanically timed, is on cranking to spray some volatile carb cleaner fluid into the (empty) airbox to see if it attempts to fire.
If so it points to fuelling still.

Your CDI burned out and was replaced 2nd hand but not yet confirmed to be working, so this (and the underlying cause) is another area of suspicion still.
The service manuals have test procedures for ignition circuitry, so well worth some time checking this before frying another CDI.

Richard.

Tuomas wrote: ....Tried to turn cams 180 degrees, did not make any difference. .

What? This can't mean what it appears to mean.

Turning cams 180 degrees forward does nothing but changes first stroke to third stroke in 4 stroke engine. Well we tried both ways (t-mark aligned, dots in cam gears pointed out or in, and engine turned without valves hitting pistons. But it won't start...there is a strong smell of gas from both aircleaner and exhaust pipes.

There is spark in all the plugs and coil pickups seem to work ok. Fuel injection and its timing is one mystery still.

Tuomas wrote: Turning cams 180 degrees forward does nothing but changes first stroke to third stroke in 4 stroke engine. Well we tried both ways (t-mark aligned, dots in cam gears pointed out or in, and engine turned without valves hitting pistons. But it won't start...there is a strong smell of gas from both aircleaner and exhaust pipes.

I understand what you are saying here and it's really the same thing. the only difference would be the position of the ignition timing relative to the camshaft timing.

Back to basics here. Recheck the timing as per the manual and then ensure the ignition timing is set properly. The ignition "fire" mark is related to cylinder 1 or 6. If the cams are timed properly and the ignition is times properly, then is no difference when rotating the cams 180 degrees since the ignition rotor will be in the same place. This is only because this engine is a wasted spark ignition system. When it fires cylinder 1 it also fires cylinder 6 when the valves are on overlap. Same with 2 and 5 and 3 and 4. I understand your thinking when you rotated the cams 180, but on this engine it makes no difference.
One thing that you may want to check is the ignition coils for cracking. Big problem on these engines because of where they placed the coils in relation to that big engine. Too much heat up there. Check for cracks down the side of the coils.
You should also check for DFI fault codes. There's a led on the side of the DFI controller. If it's flashing a pattern, it's telling you of a problem. All this is in the manual. If you don't have the ZN1300 supplement or the KZ1300 service manual (and you need both), download from the Home page on this site.

Let us know how you're making out please.
Thanks,
KB