2004 Mercury M2 jet boat, No Start/No Spark

[JBERN58]

Hi all and thanks much in advance for any input. I have a 2004 Merc 240 EFI M2 Jetboat. It cranked but would not fire on at the launch the last time out. Crank crank crank no pop at all. Prior to that, I had no issues whatsoever with this boat firing right up. It cranks over great but no fire at all. I get the one self check "beeeeeep" when turning key forward, fuel pump "clicks/ratchets" and cranks over great. Batteries are newer and are kept charged, its definitely not a voltage issue with batteries. I have checked the 4 fuses by the ECM as well as the 3amp by the fuel pump (but again, that makes noise and appears to be newer). I have an inline spark tester so I pulled one of the boots and plugged that in and had my wife crank it over while I watched. There was no spark jumping the gap. I have been scouring online but am finding little info on this to help me. A couple of things I read (and have a hunch on possibly being the issue) is either the crank sensor or the main power relay? I am hoping someone has had the exact same experience with a successful fix and can give me some ideas.

 

[Tim75]

Hi all and thanks much in advance for any input. I have a 2004 Merc 240 EFI M2 Jetboat. It cranked but would not fire on at the launch the last time out. Crank crank crank no pop at all. Prior to that, I had no issues whatsoever with this boat firing right up. It cranks over great but no fire at all. I get the one self check "beeeeeep" when turning key forward, fuel pump "clicks/ratchets" and cranks over great. Batteries are newer and are kept charged, its definitely not a voltage issue with batteries. I have checked the 4 fuses by the ECM as well as the 3amp by the fuel pump (but again, that makes noise and appears to be newer). I have an inline spark tester so I pulled one of the boots and plugged that in and had my wife crank it over while I watched. There was no spark jumping the gap. I have been scouring online but am finding little info on this to help me. A couple of things I read (and have a hunch on possibly being the issue) is either the crank sensor or the main power relay? I am hoping someone has had the exact same experience with a successful fix and can give me some ideas.

Have you checked the kill switch? It the rubber does not fully depress the center plunger, the engine will only crank. No start.
Check connection for trigger coil. Top of engine, aft of flywheel. 6 wires.

 

[JBERN58]

Have you checked the kill switch? It the rubber does not fully depress the center plunger, the engine will only crank. No start.
Check connection for trigger coil. Top of engine, aft of flywheel. 6 wires.

Thank you for the reply! I happen to be up in the boat right now so looked. I do not see this pickup. Is that on the older ones? Doesn’t this one have a crank sensor like what you’d find on a car (can’t find that either....yet). And It’s definitely not the kill switch. I ruled that out for certain. I attached some pics of what I’m looking at.

 

[JBERN58]

Pics are there now. They weren’t up loading.

I see the two wire pickup now aft the flywheel. I will check that next but not sure how. Guessing it would take an oscilloscope which I do not have. Just a multi meter

 

[JBERN58]

I just unplugged and ohmed out the 2 wire pickup at rear of flywheel. It is reading as an open circuit/no resistance measured/meter did not change from OL. I read that it should be around 300 ohms. Did I find my problem?!?

 

[AirSniper]

Yes, should be ~ 300Ω, open is not good. Been there, done that. Soak the bolts with penetrate while you wait for the new one.

 

[JBERN58]

Yes, should be ~ 300Ω, open is not good. Been there, done that. Soak the bolts with penetrate while you wait for the new one.

Thanks for the reply. Great tip on soaking bolts. I ordered a new crank sensor and am waiting on arrival. I did find this picture which might help the next guy.

 

[AirSniper]

nice. i seem to recall ~ 300Ω as correct. Please check the new one & post, now im curious.
BTW, I sheared both my bolts & had to drill out, i think the bolts were cheap, very soft metal & they were corroded into the aluminum block.

 

[JBERN58]

nice. i seem to recall ~ 300Ω as correct. Please check the new one & post, now im curious.
BTW, I sheared both my bolts & had to drill out, i think the bolts were cheap, very soft metal & they were corroded into the aluminum block.

I received the new one in the mail yesterday and immediately took it to the multi meter. You are correct, 300 ohms. The one in my boat is open so this must be the problem. I tried to loosen the bolts and can tell they are seized and going to break. Im about to drill a small hole next to the bolt heads to allow penetrant to flown to threads and hopefully loosen the bolts. If anyone else had any suggestions, I welcome them! Thought about some hear where the threads are? I don’t want to pull the flywheel and drill bolts. This should be a 3 minute job! Lol

 

[JBERN58]

New (used) crank sensor fixed the problem! Boat started in 3 seconds with new sensor. If you have a no start/no spark, this would be the first thing I check as it takes 1 minute to ohm out that sensor on top of your engine.

Both the crank sensor bolts snapped off despite soaking in penetrant for 2 days with even having holes drilled through old sensor tabs and to the bolt threads! Had to pull flywheel and drill out bolts. Then tap new threads. This was a bunch of nonsense on a job that should take 3 minutes. I fortunately had all the special tools (puller, center punch, correct size tap, etc.) to do this but for most do-it-yourself’ers, these broken bolts will be a bit of an undertaking to get drilled out and tapped.
Hope this helps someone!

 

[AirSniper]

Good for you, glad to hear this....damn bolts though.

 

[JBERN58]

Thanks AirSniper. Yeah, those bolts turned a should-be fun, easy job into a total nightmare.

 

[SeptemberC]

Thanks for the follow up!