no fire on 4.3 chev v6 mercruiser

[hydrick]

i have an 1993 mercruiser 4.3 chev v6
it's been running great till friday night.it just quit,spins over fine and is getting fuel but won't start.
i put a screw driver in coil wire boot and held over distibutor cap and see no visible arc.
we bench tested the coil granted i,m unclear exactly how the numbers should read, but from terminal post to post i'm gettin 2.2.and from center post to either terminal 10.5-10.8.

i'm stumped.do i need a coil or is there something else to check for?

also will a regular gm coil do the trick?
thanks ronnie

 

[dirtyoldman]

Re: no fire on 4.3 chev v6 mercruiser

pull the cap and see if the rotor spins when the engine cranks over.


Your coil sounds good. The coils that have failed on me worked for about two minutes, then failed as they got hot. What is the voltage at the coil when cranking and when in the run position?

While the cap is off, see if the mechanical advance works properly and check the condition of the points. It would be a good time to change these and the condenser as well.





Lastly, you say it's getting fuel - but you don't say where. With the engine off, go from neutral to full throttle and watch inside the carb. You should see the accerator pump shoot fuel. If not, check the needle valve in the carb.

If none of the above are it, pull the plugs. Are they all oily, covered in gas, etc.....

 

[Don S]

Re: no fire on 4.3 chev v6 mercruiser

Do you have power to the coil?

 

[Bondo]

Re: no fire on 4.3 chev v6 mercruiser

While the cap is off, see if the mechanical advance works properly and check the condition of the points. It would be a good time to change these and the condenser as well.

It's a 1993,....... It Should have the T-Bolt IV Igntion......

That means No Points,.... No Condenser,..... No mechanical Advance......

 

[hydrick]

Re: no fire on 4.3 chev v6 mercruiser

it's got constant power to the coil with the ignition in the run position.
it's also got a constant power to the negative side with the engine spinning,however there is no pulsing of the test light when engine spinning.
i also tried new coil wire and put a spark plug inm it and spun it over to no avail.still no spark.

the gas is pumping as it should.

i think your're right about the t-bolt.
the positive side of coil and i think negative leads to a connector on a bracket off to right side of engine. like a module of some sort.

i'm stumped.

 

[paulrfrancisco]

Re: no fire on 4.3 chev v6 mercruiser

i also tried new coil wire and put a spark plug inm it and spun it over to no avail.still no spark.

I presume you had the spark plug grounded to something, or else there will not be any spark.

 

[Don S]

Re: no fire on 4.3 chev v6 mercruiser

 

[hydrick]

Re: no fire on 4.3 chev v6 mercruiser

yes, the plug was grounded.great point for all to remember.

wow,
thanks don s for the truble shooting chart.

i'll keep you all posted.
ronnie

 

[hydrick]

Re: no fire on 4.3 chev v6 mercruiser

dons,
based on schematic, and fact that i had no fire from coil with plug grounded
would i be correct in my assumption that i need an ignition module?
thanks, ronnie

 

[Don S]

Re: no fire on 4.3 chev v6 mercruiser

Assume nothing, follow the chart and do the tests.

 

[WAVENBYE2]

Re: no fire on 4.3 chev v6 mercruiser

Don cracks me up with his straight forwardness,Well needed !!

 

[hydrick]

Re: no fire on 4.3 chev v6 mercruiser

Assume nothing, follow the chart and do the tests.

i appreciate the straight forwardness too.

i thought i had gotten that far when i had no spark at the coil.

 

[dirtyoldman]

Re: no fire on 4.3 chev v6 mercruiser

Don's chart is good, but you need to make sure that the rotor is turning when the engine is cranking. I believe that this engine uses the distributor gear to drive the oil pump, and if the oil pump siezes, it shears the distributor, and it won't start. That was missing from the chart. I've seen it happen, and it takes fifteen seconds to troubleshoot, so I do it early in this kind of troubleshooting process.

 

[hydrick]

Re: no fire on 4.3 chev v6 mercruiser

i'll check it tonight.
you know, the agony of it all is overwhelming,lol
i mean, who can live on a lake without a boat,especially after a 97-99 degree south carolina day.

 

[hydrick]

Re: no fire on 4.3 chev v6 mercruiser

wow,
no volts on red white terminal but had 1.5 on lead.
so i went with a sensor in distributor,nothing
still no fire.
i have constant 12 volts to coil(using a 12 volt test light),and since the sensor i'm now getting a pulse with a test light on the negative side with the engine spinning over,which i didn't have at coil before replacing sensor.
i've got voltage coming from the module,but absolutely -0- spark on coil.
the coil is reading 10,11000 ohms at tower and .95 to 1.0 at either terminal.
i'm really flabergasted.
this new style sensor did away with my old post design and i had to use bullet connectors to make work.
it also had a ground wire coming out that my old one did not have.i grounded it with the ground wire off the module.
i'm stumped.
the schematic now points toward coil.

my engine serial # is 0d851540 4.3 1993 alpha v6
thanks.

 

[Don S]

Re: no fire on 4.3 chev v6 mercruiser

Then try a coil.
I have seen bad coils take out the distributor sensor and ignition modules at the same time.

 

[hydrick]

Re: no fire on 4.3 chev v6 mercruiser

i've got one on the way don.

do you find it odd that i'm getting the reading on the coil, yet still no fire?

i've got voltage on the red/white and on the green/white.

 

[dirtyoldman]

Re: no fire on 4.3 chev v6 mercruiser

I do find that odd, but I've heard of it before.

Hey, coils are cheap and you need a spare anyway.

 

[hydrick]

Re: no fire on 4.3 chev v6 mercruiser

i'm beginning to wonder if it's a shifter problem.

although it shouldn't turn over at all

nah.

 

[dirtyoldman]

Re: no fire on 4.3 chev v6 mercruiser

If that could be the problem, it'd be in the troubleshooting part.

But there is some kind of switch on the inboard transom plate that lowers RPM when shifting by shutting off a few cylinders?? My dealer said something to me about that.