crank no start after head gasket. 2008 3.O Mercruiser.

jeepxjmike

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Jan 27, 2019
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I pulled motor to install head gasket. I'm at stopping point as I have crank no start.
152 PSI on all cylinders
Tested with light tester:
I voltage to purple wire at coil. Voltage to grey wire from coil
Both wires from Coil to distributor have voltage.

I have Chiltons book for Mercruiser up to 2001. It describes testing coil by probing each contact for open and shorts.
I have extra coil from buddies 3.0 installed. Both coils tested the same value.

I don't have spark on main wire from coil to distributor. I was using a Timing light to verify spark.

Does any one have an updated wire diagram for 2008 3.0?
I have a circuit breaker, No extra start solenoid.
Compression test 152 psi each cylinder .

Prior history:
I did remove the TKS in for 2002 common standard choke style Carb.
I rand 12v switched to the carb.
I ran this way for 2018 season.

Head gasket change as I was having water in oil New gasket with head checked.
I could not find signs of cracked blocked. ( I sealed cooling system added 5psi and pressured the system for 15 min. No air leak)
 

alldodge

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There should be 12V on purple wire with key ON, and it sounds like there is.

Remove the gray Tachometer wire from the negative side of the coil until the motor is running again

Get a spark tester and install between coil wire and distributor. Crank the motor over and see if your getting spark

Check to see if your getting fuel in the throat of carb when throttle is pumped
 

Rick Stephens

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Take your plugs out, all but #1 cylinder. Hook up your timing light to number 1 and crank er . See if your timing is where it belongs. Then check wire order again. Easy to get them out of order.
 

achris

More fish than mountain goat
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Take your plugs out, all but #1 cylinder. Hook up your timing light to number 1 and crank er . See if your timing is where it belongs. Then check wire order again. Easy to get them out of order.

And the timing light will fire how? (He has no spark!)

Chris.......
 

StinkinRenken85

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I burnt through a couple coils after installing a pertronix electronic ignition in a real short time frame because I didn’t have it wired right...not saying that’s what’s going on here but no spark from the main wire from the coil to the distributor sounds familiar to me. I’d put a new coil on there and test for spark. I know they say don’t throw parts at a problem but coils aren’t too expensive and if it’s not the problem you will have a backup.
 

Scott Danforth

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Tested with light tester:
I voltage to purple wire at coil. Voltage to grey wire from coil
Both wires from Coil to distributor have voltage.

you have a wiring issue

the grey wire is the tach, not needed to start the motor - so disconnect it. if you have voltage at the grey wire, you have an issue. the black wire from the dizzy simply pulses ground to the negative side of the coil. to verify the coil, etc. simply have battery voltage to the coil + and take a wire from ground to the coil - and pulse it. you should have spark

I have Chiltons book for Mercruiser up to 2001. It describes testing coil by probing each contact for open and shorts.
I have extra coil from buddies 3.0 installed. Both coils tested the same value.

I suggest you throw away the knee pad and get the factory manual.

there is also a TB ignition troubleshooting guide in the stickies.
 

jeepxjmike

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Jan 27, 2019
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I have the manual i seloc 92 00 not as up to date as I need. but helps with basic things

where in the stickes might i find the wire diagram for 2008?
With the light tester i have voltage on the grey wire.
 

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alldodge

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Did you remove the TKS carb before the head gasket replacement?
If so, was the motor running OK after the TKS carb was replaced?

What caused the head gasket replacement?

Test lights are OK, but you need a voltmeter
 

jeepxjmike

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The boat did run after tks carb removal. Buddy gave me a parts motor.
Water in oil for head gasket. Not sure if it ever ran well. This thing as been a pain since a bought it. Bought it off 74 year old lady who never really used. it. Come to find water in oil.
Not sure if it ever ran well. 3.0 always struggles. It really a dog. I have had small outboards with more ass.
 

jeepxjmike

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I burnt through a couple coils after installing a pertronix electronic ignition in a real short time frame because I didn’t have it wired right...not saying that’s what’s going on here but no spark from the main wire from the coil to the distributor sounds familiar to me. I’d put a new coil on there and test for spark. I know they say don’t throw parts at a problem but coils aren’t too expensive and if it’s not the problem you will have a backup.

It has to be type wiring issue. It might be bad second coil. (Maybe, but they measured about the same resistance. )
Maybe bad ground to coil? I cant see it as it's bolt to block. I might try a jumper from battery ground to base of coil.
 

alldodge

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Since it ran before head gasket replacement I'm assuming its not motor related

Here is wiring for EST ignition
Check for 12V (not test light) on purple wire.
Then check for spark as mentioned above, or at coil to a ground

3.0 wiring.jpg
 

jeepxjmike

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Since it ran before head gasket replacement I'm assuming its not motor related

Here is wiring for EST ignition
Check for 12V (not test light) on purple wire.
Then check for spark as mentioned above, or at coil to a ground


I have. 12.39 volts on purple wire on coil. 12.39 volts on red and brown wires going to distributor. White black wire to distributor 12.39 volts .

My style wire harness has a Relay instead of solenoid
The relay has yellow / red , Red, black and yellow / brown.
 
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alldodge

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Other then Purple, I'm not finding those colors on the distributor

Is the rotor turning and the cap clean?

What is this

dist.jpg
 

havoc_squad

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I would be guessing that is the OP's light spark tester in line between the ignition coil and distributor.

If it is not that, then I'll be really curious to find out what thing is.

By the way, the mercruiser factory service manual gives a good no spark troubleshooting proceedure for the Delco EST ignition.

I've used it beforehand to rule out ignition issues.

http://boatinfo.no/lib/library.html

I think either #26 or #13 will work for the Delco EST ignition troubleshooting steps.

#26 manual should be the current version for your motor.

Timing adjustments at base timing should however be done using the manual matching your year/serial number if there any differences.
 

jeepxjmike

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I would be guessing that is the OP's light spark tester in line between the ignition coil and distributor.

If it is not that, then I'll be really curious to find out what thing is.

By the way, the mercruiser factory service manual gives a good no spark troubleshooting proceedure for the Delco EST ignition.

I've used it beforehand to rule out ignition issues.

http://boatinfo.no/lib/library.html

I think either #26 or #13 will work for the Delco EST ignition troubleshooting steps.

#26 manual should be the current version for your motor.

Timing adjustments at base timing should however be done using the manual matching your year/serial number if there any differences.

Thanks I was able to use the manual after finding scroll bar to search manuals above 4.
I'm looking the kill switch on off. This wire has two purple wires How does this kill the circuit?
 
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havoc_squad

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Thanks I was able to use the manual after finding scroll bar to search manuals above 4.
I'm looking the kill switch on off. This wire has two purple wires How does this kill the circuit?

The purple wire to the ignition coil is the on/off to the ignition. There is only one purple wire.

Please reference Page 1C-10, about page 56 of the service manual.

Pink is the power from coil to distributor. This power does 3 things.

Gives power to the electronic brain that manages the timing advance.
Gives power to the magnetic sensing of the next ignition coil firing
Triggers the logic to short the ignition coil wiring to ground, creating spark.

The brown wire going from the distributor to the coil has one purpose, on command of distributor to short the voltage on the coil to ground, causing the ignition coil to fire for spark.

The single wire on the 3 pronged connector on the right side of the distributor white/green is strictly for the shift interrupt switch that briefly interrupts ignition when coming out of gear (if my memory is correct.) If the shift interrupt is not working right or not connected properly, this can cause diagnosing complications.

The two white wires with plug connectors the three pronged connector to distributor are for putting it in base timing mode, which is covered in the service manual.

As long as the ignition system is working as expected and the motor is running as it should, ignition will ONLY be on/enabled as long as there is 12 volts on the purple wire.
 
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Bondo

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This wire has two purple wires How does this kill the circuit?

Ayuh,...... Welcome Aboard,....... It's a simple pass-through switch,......

The switch either makes, or breaks the circuit,.......
Ignition power comes from the key switch, through the safety(mob) switch, to the motor,......
 
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