99 Power at coil no spark

"I have a 4.3l Mercruiser in a

"I have a 4.3l Mercruiser in a 99 Bayliner Capri.

It has been running fine, sometimes a little run on (dieseling), but other than that, it has been fine.

One day a few weeks ago, it stalled in the middle of the lake, and took a lot of cranking to get it going. That problem re-occured once, but on both occasions, it started again. I chalked it up to running rich (which I thought was also causing the run-on - not sure).

Yesterday, plopped it in the lake, turned the key, and it was completely dead. Turned the key again, completely dead. Third try, it started turning over - but would not start.

Ran down battery trying to start it, then used booster pack and still no go.

Yanked it out (with a smile on my face ;-) and brought it home. Charged battery, still no start.

Measured power at positive side of coil, and very light current at negative side (maybe drain?) Popped a new cap and rotor/pickup set in, no go. Swapped in another coil (not sure if right one) and still no go. Power at coil again, and nothing at all at negative side - not sure if this has fixed a problem or introduced one.

Disconnected and re-connected main wiring harness in engine compartment (added some dielectric paste for good measure)

Snipped one of the emergency cutoff wires at throttle lever in case switch was defective - still no spark, fixed wire

Every time I changed something I checked for spark at the coil and spark at a plug - never got one.

Not sure what to check next.

Any advice on what to check would be appreciated.

Thanks in advance."

Have you checked the timing ??

Have you checked the timing ??

"No, I thought that may be the

"No, I thought that may be the dieseling problem, but I was reading that most of the time it is fuel mixture related - not timing. No spark though - timing could be off, but should I not still get spark?

Runs fantastic once it starts. Idles low and smooth, no pinging, heitation or anything."

What about a bad cable or not

What about a bad cable or not a good ground and i am not trying to be a pecker head but when you replace the cap and all that did you make sure everything was in the right place??

also make sure that the kill s

also make sure that the kill switch that you cut is making contact i done the same thing and crimped the the thing in two and when i found it i said some cuss words ... I don't understand no spark then when it does start it runs fine ?? Is this a carb boat or EFI?? Is it getting fuel ?? check you filters and see if they are clogged!!There are guys on here who are Gurus and very boat savvy i just learn from what has happened to me there are guys like Bondo Guy gaspar Kurt S and Rod Stewart they are pretty awesome on questions use them on a thread they usually respond quickly ... One other question do you have an engine manually??? I would also check the ignition switch

"Multiple sources of such prob

"Multiple sources of such problems, some cheap, some a little more costly.
Dirty connections at battery and/or engine connections.
Weak and/or dying battery.
Charging system not keeping battery up.
Dirty or failing solenoids for the starting system.
Starter dying - sometimes act good, sometimes act bad.

Since when you get it going it runs decent, not likely coil, cap, or plug wires. More likely insufficient juice for any of the above reasons. Once you get this problem fixed, a good tuneup could be helpful."

"It was running fine last week

"It was running fine last weekend, and just starting giving me starting grief.

Last week, when it was running, it was great.

Cap, rotor, and pickup was changed by local maring mechanic, so I assume it is in right. They are now closed until Monday, so trying to get back on the water without them

Battery is strong, charge is good - almost 15 volts when running.

Turns over well - good strong cranking.

what so you mean make sure kill switch you cut is making contact - i cut the wire to make sure it was not shorting ground. Does it need to be connected?

it is a carbed boat - seems to be gas, just no spark.

Where are the selonoids? Can they be checked?"

"I would check your key switch

"I would check your key switch first at the I terminal; purple wire.
This should be hot with the key on.
If it is, check any purple wire at the engine; which should also be hot.
If this checks out and you have no spark, you have a bad coil or ignition module.

Rod"

What is the I terminal?

The

What is the I terminal?

There are two wires in behind the switch - purple and purple/white.

You are saying the solid purple should be hot at the switch itself?

I just installed a new tachome

I just installed a new tachometer from the dealer (same manufacturer - Faria) - is there any chance in hell this is causing my problem? I have not tried to start the boat since I installed the new replacement tach.

"---- I just installed a new t

"---- I just installed a new tachometer -- is there any chance in hell this is causing my problem? -----

Yep, the tach is in the circuit that the ignition system uses. Check over the wiring job again. And of course the tach itself could be defec"

"Try this test.

Tests for T

"Try this test.

Tests for Thunderbolt Ignition:
W/ignition key on AND BILGE WELL VENTILATED OF GAS FUMES!!!

#1 - Connect your voltmeter neg. lead to the engine ground and pos. lead to the white/red wire terminal at the dist. It should read 12 volts.

#2 - If 12 volts is present, remove the coil spark wire from the distributor and connect it to a spark gap tester to ground. Remove the white/green lead from the dist. terminal. Turn the ign. key to on and strike the white/green lead to ground. If there is spark, replace the ignition sensor in the dist.

#3 - If there is no spark, substitute a new coil and repeat test #2. Now if you get spark, install a new coil. NO SPARK, replace ign. amp.

#4 - In #2, if there is No voltage present, disconnect the white/red wire and check it again for 12 volts. If 12 volts is present, replace the ignition sensor inside the dist. cap. If no 12 volts present w/it disconnected--ignition amplifier is shot and must be replaced."

"Thanks to all that posted - I

"Thanks to all that posted - I found the problem - it WAS the tachometer.

When I purchased the boat, the tachometer did not work (it was seized). I sent it away to faria to get repaired, and they sent me a brand new tachometer. The plug on the back is in a triangle shape (so as to fit only one way) - must be a short in the tach somewhere that is grounding something out.

Simply unplugged the tach, and she fired right up. Back in business - THANKS SO MUCH!"