Question: My Mercruiser 3.0L Marine Engine will crank over but won’t start. Is there an easy place to start when trying to diagnose this problem?
Answer: There are 3 basic fundamentals with the operation of an internal combustion engine
Mercruiser 3.0 Turns Over But Wont Started
I decided to take my girls wakeboarding on my 21 ft cobalt (I know I should have bought a chaparral but I did, this is my second boat) and it wont start. Not even turn over. The batteries are both fully charged. The boat is definitely in neutral. Shut it off and fueled it up. When we went to leave it would turn over but not start. They had fueled over 20 boats that day with no complaints so don't suspect bad gas. I checked every engine connection, the kill switch by the throttle, and even tried to start it in neutral with a bit of throttle. Not even a cough. Turns over and over like a. The starter turns over but the engine will not start. We put a new fuel filter and spark plugs but it did nothing. Im not a mechanic but it seems like it is not getting any gas. But im also scared it could be a cracked head. Does anyone know what I can do to test my theories or if you have any advise feel free to let me know thanks! It will turn it just will not start if anyone has some good advice let me know Im new to the boat world This boat has been sitting for about 2 years they got it running once in that time frame.
- Spark
- Fuel
- Timing
Mercruiser 3.0 Turns Over Wont Start
As illustrated in the short video below it is very easy to verify if the engine is in fact getting the required spark at the distributor, and subsequently each cylinder. We like to use a standard engine timing light while connecting it to the main coil wire lead in between the coil and distributor cap. Once you have the timing light connected you can crank the engine over and visually verify if spark is being supplied from the coil to the distributor. In the event that you do have spark we typically go ahead and verify that each individual cylinder is also getting spark. This basically eliminates the distributor cap as a potential problem item as well.
If you do not see that the coil is providing spark to the distributor cap it can either be the coil itself or possibly the engine control module. At this point you can either test or in some cases the coils are relatively cheap and its easier to just take your chances and replace the coil.
Tags: 3.0l trouble shooting, coil, no start, trouble shooting