No spark from coil after 5 cranks??

[jimbob1212]

Got a 1998 4.3 V6 mercruiser. Anyone know why I would get no spark after about 5-6 cranks? I have changed the coil, cap, rotor, ingnition switch. can't figure it out? checked all the connections, cleaned them up and still nothing.

 

[bigbrownbuku]

Re: No spark from coil after 5 cranks??

check your oil pressure switch

 

[jimbob1212]

Re: No spark from coil after 5 cranks??

didn't check it 'cause the dang thing ran for about 10-15 min. like a champ. pressure and temp were both fine turned it off wnet to start it again and this is where I am.

 

[Don S]

Re: No spark from coil after 5 cranks??

The oil pressure switch controls the electric fuel pumps, not the spark.
I would start checking for loose and corroded connections. Sounds like with current passing thru the connection it stops, possibly due to high resistance.

 

[jimbob1212]

Re: No spark from coil after 5 cranks??

switch seems fine. cleaned off connections same result.

 

[b0mbtrack]

Re: No spark from coil after 5 cranks??

what about bypassing the key switch and using a start button with a jumper wire to the coil. if it starts then you can isolate the problem a bit

 

[jimbob1212]

Re: No spark from coil after 5 cranks??

If you mean run a jumper wire from the + battery to the + side of the coil I did that and no luck. Any other thoughts I am completely open!

 

[b0mbtrack]

Re: No spark from coil after 5 cranks??

you probably then either have a bad ground from the coil or just a bad coil because if you have juice going to it but nothing going out i think those would be the only two things that would be wrong. i wouldn't know how to test a coil though

 

[jimbob1212]

Re: No spark from coil after 5 cranks??

I tried another coil (new) and nothing different happened. How does the coil ground? is it the - side?

 

[b0mbtrack]

Re: No spark from coil after 5 cranks??

i'm not sure honestly, i think the (-) sides goes to the distributor. do you have a spark tester, can you see that there is a spark coming out of the coil or not. in other words after those 5 cranks where does it loose the spark, at the coil itself or at the plugs

 

[jimbob1212]

Re: No spark from coil after 5 cranks??

Yep your right. I put a tester on it last week and I have spark coming out of the coil wire to the distributor for 5-6 cranks then no more spark. Sometimes it starts VERY rough as the spark quits.

 

[b0mbtrack]

Re: No spark from coil after 5 cranks??

that is a tough one. i'm not too familiar with what other electrical system is hooked up to the ignition. if there are some wires going to other components to disconect to see if we get spark back but i wouldn't even know where to start. if i think of anything i'll let you know.

 

[cooter2506]

Re: No spark from coil after 5 cranks??

Thunderbolt 5 Ignition?

 

[cooter2506]

Re: No spark from coil after 5 cranks??

My 5.0 did the same thing and I was so stumped I took it to the marina. they found bad ignition module. Small but expensive piece. But now it runs like a champ

 

[jimbob1212]

Re: No spark from coil after 5 cranks??

Hey guys, thanks for all your help. I got it. Started tracing every wire AGAIN and when I came along the wire fro m the starter to the nuteral saftey switch I un plugger it and WAH-LAH Dame started right up. Thanks again!!

 

[Don S]

Re: No spark from coil after 5 cranks??

It must have been the safety kill switch you did something to, cause the neutral safety switch has nothing to do with spark. Only the operation of the starter.

 

[Boatist]

Re: No spark from coil after 5 cranks??

I do not know your motor at all but if you have 12 volts on the plus side of the coil and no spark I would check the DWELL, Points and condensed or the pick up that replaced the old style points. With 12 volts on the plus side of the coil then you need to ground and un ground the Minus side of the coil and you will get a spark. That what the old style Points and condenser did. If it does not have points and condenser then it has some type of electronic module that does the same function.
Please tell us what you find.