1997 Mercruiser I/O won't start

[rag7200]

I have a 1997 Regal with a 3.0 Mercruiser I/O. I've just tried to pull a skier up, probably 10 times, the engine is running perfectly and has been all day. I pull up to the worn out skier and turn the ignition off to ask if he has had enough for one day. He climbs in and we're ready to head home but now the engine won't start or even crank. Nothing! I wiggle the shifter, again nothing, I move the shifter a lot... several times... then suddenly it starts cranking but still won't start. I removed the air filter and pumped the throttle to confirn that I was getting gas, and it was... Cranked until battery was weak... called for a tow... Once we got the boat to the dock I removed one of the spark plugs and asked my wife to turn the ignition so I can check for spark... the boat starts and runs on three cylinders... I shut the boat off, replace the spark plug, restart the boat and move it to the other side of the dock. My wife climbs aboard to go for a test drive but now the boat won't start again. Cranking but not starting... no fire to the plugs. My question is, do I have one problem or two? It seams odd that I would have two different problems at the exact same time. I've owned the boat for 17 years and never had either of these issues; but I can't see how they're related either. I haven't had a problem with it not cranking since I've had it home but I still don't have spark to the plugs. What is the proceedure for finding the "no spark to the plugs" issue?

 

[Watermann]

Take a look at the ignition module in the distributor, they are a likely culprit for the intermittent spark problem before total failure.

Not sure why you would loose power to the starter though?

 

[tpenfield]

Kill switch / lanyard would be something to check to see if it is intermittent. How much did the tow cost?

 

[rag7200]

Thanks! How can I tell if the ignition module in the distributor is bad (other than replacing it)? Would the kill switch / lanyard interupt power to the starter or fire to the plugs? The tow was free. I should have said, "I called a friend for a tow".

 

[Watermann]

Normally a kill lanyard cuts the ignition power to the coil and shuts off the motor that way but it would still turn over with the starter just never fire. The first turn of the key sends power to the coil and when you turn the key to start it sends power to the solenoid to turn the starter. I would use a tester to see if there's 12v power going into the coil, I think it's the purple wire. If there is power then it's not the kill lanyard and could be the ignition module not sending the power to the plugs. Most of bad ign mods I've seen look melted or scorched but not always. Check the connections on the kill lanyard, ignition switch and on the starter to be sure they're all good.

One easy way to see if it will start and bypasses all the junk is to hot wire the coil with a jumper from the battery to the coil terminal and see if she runs then. remember in order to turn the motor off you'll have to disconnect the jumper wire. if it won't start with a hot coil then it's probably in the distributor.

 

[redneck joe]

and welcome to the forum.


17 years on same boat. good job.

 

[rag7200]

Thanks guys. I headed outside to do some testing after your replies but the boat started every time I hit the switch. I'm taking it back to the lake tomorrow hoping that at some point it'll decide to act up again so I can do some testing. Can you give me more specifics on how to hot wire the coil? Are you saying pull the purple wire off the coil and run a wire directly from the positive battery terminal to where the purple wire plugs into the coil? If so, what size wire do I need to carry the load? Also the purple wire has a grey wire in the same connector with the purple... ok to disconnect that too?

 

[achris]

If you don't have a circuit diagram of your ignition system, Click Here...Once you have that you can follow the circuits. The purple wire provides power to the ignition system. If it were me and I was looking for an intermittent fault like this, a handful of LEDs would be going on to the system. I would be fitting them and using them and a diagnostic aid, having them already in place rather than trying to fault find with a multimeter at the time.

First place I would put an LED (and you can buy LEDs that are set up for use directly on 12v with the current limiting resistor already 'built-in') is on the Purple wire on the connector at the coil. That one should have power at all times except when the ignition switch is off. That will tell you straight away if you have a supply problem. The second one I would put in the Wht/Grn wire connector between the interrupt switch and the distributor. That one should be off unless the interrupt switch is activated. When you have the problem, look at that one, if it's lit, the interrupt switch may be the problem (as long as the cable isn't pulling it).

HTH,

Chris.......

 

[rag7200]

Thanks Chris. Where is the best place to buy LED's?

 

[Rick Stephens]

LEDs are easy. Just look for 12 volt ones. Something like these would work well.

Rick