I have a problem with a 80 series 1FZ-F carburetor model, the number 3 spark plug is always full of petrol when I start the car have recently done valve stem seals.
80 series spark problem
- Thread starter johanrossouw
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I'm assuming you are asking for help and not just informing us of your findings. What troubleshooting have you performed? Have you checked for a strong spark at the spark plug with it removed? If none then work back from there. Problem is likely the plug, the lead or the distributor. If you do have a strong spark at the plug, then check compression on that cylinder.
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- #3
Spark at the plug is 100% but the plug is always covered in petrol when I leave the car off for an hour (new NGK spark plugs fitted and new leeds) have already checked compression and it is 100% as well
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- #4
Could it be a leaking Carburetor?
I'm assuming that none of the other plugs are wet with petrol?
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- #6
Yes sir
I can't see how a problem on the carb would manifest itself on only 1 plug. Did you do the compression check yourself or was it done by your mechanic?
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- #8
Done b
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- #9
Done by my mechanic
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- #10
Wont the same valve stay open when the car is switched off?
Nope. When you shut down the the engine, momentum will allow the engine to rotate a few degrees but it won't always stop with the inlet valve on #3 cylinder open. In any case, fuel enters the cylinders by way of a venturi effect so without the engine turning there is no venturi effect.
Are you able to do the compression test yourself and post the values recorded for each cylinder?
Are you able to do the compression test yourself and post the values recorded for each cylinder?
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- #12
Will
Will do so tomorrow and keep you updated, what do you think might be the problem if compression is low on that cylinder? And if compression is fine where can we start to look? Ps. As soon as i change the plug the cylinder is fine but as soon as I switch off and leave for about an hour the problem comes back. The problem goes away if I drive for more than 50kilos as well
Im still thinking that it is compression related. We will know for sure when you get new measurements.
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- #14
I've never seen a picture of the intake manifold for a carb motor but it makes sense that a leaky carb would leak downward meaning that cylinders 3 & 4 would be where there would be expected evidence of the leaks. Sounds like the carb needs to be rebuilt, resealed and float bowl level adjusted.
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- #17
Bought a brand new compression tester this morning
cyl1 : 1255kpa
Cyl2 : 1250kpa
Cyl3 : 1225kpa
Cyl4 : 1225kpa
Cyl5 : 1300kpa
Cyl6 : 1300kpa
toyota manual says the ideal compression should be 1175 kpa with a less than 98kpa difference between cylinders
cyl1 : 1255kpa
Cyl2 : 1250kpa
Cyl3 : 1225kpa
Cyl4 : 1225kpa
Cyl5 : 1300kpa
Cyl6 : 1300kpa
toyota manual says the ideal compression should be 1175 kpa with a less than 98kpa difference between cylinders
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- #18
Think the car might have carbon build up in cylinders that would explain the higher readings but still the difference in pressure is minimal from cylinder to cylinder