Is this a combustion sensor?

[Big dreams]

Motor turns over but will not fire up. Symptoms of a kill switch. The boot on this is damaged and did not have contact with the threaded screw coming out of the sensor I presume... Looks like the cowl was rubbing on the boot. Moter is a 1999 EFI 200hp.

[leonreno]

Looks like it’s mounted to a head bolt, maybe a temp sensor? Provide serial number so someone can give you specific info.

[lpugh]

Knock senor I think ……..Is that a white/purple wire to it or a cylinder head temp sensor
Serial number please

[Big dreams]

Was curious as to the serial number as well. I didn't find it on there anywhere visible. The wire is Blue and white.

[Big dreams]

Knock sensor is something I came across when I googled Combustion Sensor. I think they are the same.

[Big dreams]

For clarity, it is coming out of the top of the left head.

[boatwrench]

That is a knock sensor. It is installed on the wrong bolt hole in the head, that is why the cowling is making contact with it, should be on the same head but to the right of the thermostat. It is also not causing your problem.

[Big dreams]

That is a knock sensor. It is installed on the wrong bolt hole in the head, that is why the cowling is making contact with it, should be on the same head but to the right of the thermostat. It is also not causing your problem.

Thanks for your feedback. Not sure which hole it is suppose to be in so that is good to know. I will check into changing it to save the cowl from hitting it. Also, the motor did not start until I applied pressure to the plug. It is clearly separated and not making a connection. I am not a mechanic but no pressure = no start, pressure = start.

[JOE54]

That is a knock sensor. It is installed on the wrong bolt hole in the head, that is why the cowling is making contact with it, should be on the same head but to the right of the thermostat. It is also not causing your problem.

exactly ,obviously some one has been scrambling things on that mtr those cyl temp wires are not routed correctly either they need to be on port side of block

[Big dreams]

Just called a local marine shop. Owner came back with they don't sell the boots separately. I would have to buy the entire assembly for $450. That really sucks.

[lpugh]

Just called a local marine shop. Owner came back with they don't sell the boots separately. I would have to buy the entire assembly for $450. That really sucks.

There are 90 degree vacuum line connectors available at parts that are very similar to what you need for a boot. Replace, relocate the sensor with a new electrical connector and boot. After installing the sensor and wire you could also just incapsulate it with a very good RTV sealant to water proof it as a last resort

[EuropeanAM]

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Theoretically, the boot does nothing other than protect the connection from moisture/corrosion. Any solid connection at the sensor, that is coated with liquid electrical tape would essentially accomplish the same task.

Need to check the basics... Compression, Spark, and Fuel Quality/Delivery/Pressure