Engine cranks but will not start

[kulle]

So had boat out for first time, boat started right up on first crank and ran great on water. Was at local lake within 10 mins of house so not a far drive. Took boat back out a few weeks later, it took awhile to get it started at launch which I thought was odd. Got it going but it didnt seem to be running quite right...got a few hundred feet from dock and it shut off. It would not immediately restart. After a good 5-10 it started so we went a little further, again, engine didn't seem quite right...was cruising along and then it just shut off again and would not restart. had to be towed back.

Prior to going out , i had topped off the gas ( had about half) - thats only change since we had it out when it worked great.
Got it home and was poking around, found a loose spark plug wire, locked it back on and it still would not start. Checked connections, etc. and pulled off wire harness going to ignition module? connected to back of distributor. I found a ground wire not connected, almost as if it was purposely shoved up in the rubber boot that protects the harness. I jumped it to the ground side of the ignition coil ( was not getting voltage w/ key in run position on coil ?) soon as I attached that ground wire, i got voltage and the engine started after a few mins of cranking. let it run/idle a little then shut it off to permanently mount the jumper. once complete went to fire back up and it would not start. I'm pretty mechanical and good with electric but new to marine stuff.

I don't know if that ground wire needed to be hooked up or was coincidence it fired up or if another component is failing. I can't imagine it's anything major as it was just running good. Can't imagine its the electric fuel pump, since when started it runs. Could it be the oil sender switch? Could be the ignition coil? I understand if that fails it shuts off power to fuel pump. Looking for some experienced advice and what to check.

Thanks for any help....just bought the used boat and it started when we picked it up

1993 Sea Ray 180 BR | Engine:

MERCRUISER 1993 4.3L 443B1003S 4.3L/4.3LX ALPHA ONE ENGINE (262 CID) GEN II

 

[Bondo]

I found a ground wire not connected, almost as if it was purposely shoved up in the rubber boot that protects the harness. I jumped it to the ground side of the ignition coil ( was not getting voltage w/ key in run position on coil ?)

Ayuh,.... Welcome Aboard,...... Something odd here,.....

That ground wire can be screwed to the bottom of the distributor base,(there's a hole for a screw for it) but usually isn't, relying on the base to block contact for distributor ground,....

But,..... With the key On, there should be battery voltage to the (+) terminal of the coil,.....
'n if ya ground the (-) terminal of the coil,.... No way the motor should run,.... that's where the distributor tells the coil to fire,...

 

[kulle]

So not sure I am clear on what you are saying. The ground wire on the ICM harness had a ring end like it should be bolted down. It was short though and i didn't see any close by bolts to ground it to. I dont understand how it ran prior to me finding that ground wire not connected- so should I be focusing on the ignition coil not getting good spark to the distributor?

 

[Gregham]

Did you find your problem? I am dealing with the same issue!

 

[Bondo]

So not sure I am clear on what you are saying. The ground wire on the ICM harness had a ring end like it should be bolted down. It was short though and i didn't see any close by bolts to ground it to. I dont understand how it ran prior to me finding that ground wire not connected- so should I be focusing on the ignition coil not getting good spark to the distributor?

Ayuh,..... You'd have to pull the distributor to see where the hole is for that wire, which is why it's rarely hooked up,....

It does Not go to the (-) terminal of the coil,....
There should be a wire to the tach, 'n a wire to the distributor on that terminal,.....
'n possibly one to the shift switch,....
But No ground wire on it,....

Disconnect all the wires on that terminal, except the one to the distributor, 'n see if it starts,....
Maybe yer tach is goin' bad,....

 

[kulle]

Ok so yeah after reading more and reviewing diagrams, I removed the "ground" jumper from the ICM to the "-" side of coil. I bought a inline spark gap tester and hooked up to the HT lead of coil to distributor. Fired engine, didn;t the SUMMA BEECH start right up on first key turn ! I didn;t change anything ! ( other than remove that jumper which boat started when i had tat in place too). So i tried starting it like 4more times and it started on each first turn of key ! So i have no idea what caused it not to start well. The summary is this:

Had boat out for first time since i got it, fired up at launch first key turn, ran excellent for about 2.5 hours.
Didn't get chance to take boat out until like ~2 weeks later
Stopped to top off gas before.
got to launch, boat wouldnt start, just cranked and cranked then eventually started ( i thought was strange)
went out a little, it shut off, took awhile but i got it started again
went little further, it shut off, this time could not restart, had to have it towed.
got it home and later same day got it to start again, but took a bunch of cranking- figured something still was wrong.
3 days later -to now - i simply put that spark tester inline and tried first time and boat started like a brand new engine.

A friend with some boating experience, told me to mark and take off dist. cap and clean contacts , check for moisture.

Weird !

 

[kulle]

update was out there cleaning some things up, planning to take boat out this weekend. I test started it 3 times about 20 mins ago, it started on first key turn. Put engine cover back on and buttoned it up, did a final test start before i put cover on it and it would not start again! I have no idea what is going on. I guess I need to go through that ignition troubleshooting guide to a "T' - I did the spark test but did not disconnect the grn/wh wire and strike to ground. Could the coil ignition sensor be bad? just weird.

 

[kulle]

latest update to all the various posts, sorry moderators...

To recap had issues keeping boat running more than like 45 secs, replaced oil pressure swtich, seemed to fix issue on muffs. When i would get er in the lake under load, variuos full throttle or just low RPMs, it would randomly shut off. Removed neutral safety switch when this happened, didnt make a diff, replaced coil, internal sensor in distrib cap, cleaned the cap, cleaned arrestor found loose battery ground, tightened that thinking that was problem, but still persists. checked fuel vent-clear and checked fuel pickup fitting to ensure the ball as still moving, replaced fuel filter and checked screen on carb inlet. Have not drained gas....confirmed good 12V on fuel pump when idling/running.

Most recent issue was on lake and it shutoff, went to get it back on trailer and pushed trim up and it moved like an inch before none of the up/down/trailer buttons worked. got it out of water and manually jumped up solenoid with 12v but noticed that didnt work right away. After getting it home i found the grounding bolt on the trim solenoid bracket loose! tightened it and wa la, all trim works.
Question for all you experts: could that loose ground be a factor in my boat shutting off randomly??

 

[dlogvine]

just a thought, did you look at the ignition wires, looks like you have an intermittent problem, could be a bad contact either getting power to distributor or to the spark plugs. Possibly there is a bad connection somewhere, and the key word is possibly. Good luck buddy

 

[achris]

Just been read all the threads you have started basically on this problem... One problem, one thread... Thanks.

Have a read of my TB-IV document to understand how the system works. That will answer a lot of your questions.

http://forums.iboats.com/forum/engi...-mercruiser-thunderbolt-ignition-systems-work

Chris.......

 

[kulle]

I went through it once but will attempt a second pass. I would expect no start conditions, but my luck its a faulty ICM.

 

[kulle]

One other thing i noticed when i turned the steering wheel to one side, a cut in the u joint bellow. I water was coming in there could that make the boat run like crap under load or even shutoff?

 

[Maclin]

One other thing i noticed when i turned the steering wheel to one side, a cut in the u joint bellow. I water was coming in there could that make the boat run like crap under load or even shutoff?

Almost certainly not related.

 

[kulle]

Didnt think so...just checking all observed issues. From what I understand a slight rip in the bellow, while not ideal, I should still be able to use the boat?

 

[achris]

From what I understand a slight rip in the bellow, while not ideal, I should still be able to use the boat?

Definitely not! Water gets in the bellows and it's goodnight gimbal bearing, uni-joints and likely front seal in the drive (and the yoke)...

Fix it before you get that boat anywhere near the water!

Chris........

 

[nola mike]

[/b][/u]

Definitely not! Water gets in the bellows and it's goodnight gimbal bearing, uni-joints and likely front seal in the drive (and the yoke)...

Fix it before you get that boat anywhere near the water!

Chris........

And, ya know, you could sink.

 

[achris]

And, ya know, you could sink.

That too.

 

[kulle]

Well i feel like i got totally screwed on this boat. How big of a job is it to replace bellows, joints and seals?

 

[wahlejim]

Bellows are a regular maintenance item so you should familiarize yourself with that process now if you want any i/o boat. The first time will take about 4-6 hours for the bellows depending on how fast you move and if you have the right tools. After that, 2-3 hours. I would recommend changing them to anyone who buys a used boat. So that alone doesn't mean you got screwed.

While you have the outdrive off, inspect the u-joints and gimball bearing. Those are also do it yourself items that take awhile the first time, but as soon as you figure it out, much easier the 2nd time around. The sooner you do the work, the better chance you have to catch it before the u-joints and bearing go bad.

 

[kulle]

Ok, thank you. Is there a " how to" video and/or listing of special tools needed.