If the engine does not start it can be due to several issues and mainly it can be due to poor fuel settings and ignition timings. Also as noted by you if the compression ratio is different in cylinders then this can be bad for the performance of the engine. So it is best to check in the first place the compression on each of the cylinders,if there is difference on them then it must be seen if a correction of the valve settings can make a difference. If not the engine might need a overhauling with inspection of the cylinders.
Once the compression is good then fuel pressure settings- the pump calibration , and also the ignition system and timing must be checked even if the timing belt is in good condition.
I suggest that opinions also must be taken with estimation before you decide or change spares.
Total loss of compression would mean a bent valve. car would be running very rough if that was the case. Or a blown head gasket .The lack of compression is probably from being flooded.Check the intake if it is FULL of oil then really bad.
It could be the intake valves have gummed-up due to all that oil in the intake. If so, the thing to do is remove the heads, clean, and check for damage. The engine flooded with gas can bring compression all the way down,Gas washes all of the oil off of the cylinders and that's what seals the rings to the cylinders. You spark plugs are most likely gas fouled too.Also other possibility for no compression or low compression is the cylinder walls gets bad thats why no compression car needs a block.
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An engine will not start if it has very low compression. It could be possible that the vehicle is getting flooded with too much fuel causing the cylinder walls to get washed down.
What you should try doing is removing each spark plug and then squirt a small amount of oil (3-4 shots from oil can) into each cylinder and crank it over to re-lubricate the cylinder walls. Then re-check compression. It should jump up and be about double your first reading. If so then re-install the plugs and try to start it. If it does fire up it is going to smoke very heavily for a few minutes due to all the oil in each cylinders. -------- Try this , but if that is not helping then ignition coils needs to be replaced.Also get the spark plugs checked.If dirty fouled up and very old, then replace the spark plugs too.---------- This should help.thanks.Helpmech.
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1995 bmw 740i this car ran perfect didnt drive for a couple weeks try to start engine cranks over doesnt fire check compression varies from 60-130 if i remember correctly wrote down checked 10 days latter approx same variation but differant cyd some that were low now normal and vice versa, time chains are good
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