Mercruiser 3.0 No Spark issues

[aidanmurphy]

Just picked up a new to me 1991 Stingray with a Mercruiser 3.0. Boat ran great the first 5 times I took it out. Last time I was out boat was hard to start, then after I had stopped for a bit would not start back up. I went through the fuel system and it is all good. I hooked up inline spark tester between the ignition coil and distributor and can't find any spark there. I tried disconnecting the tach, and no start still. I have read about trying to disconnect the shift interrupt switch but not sure how. I tried disconnecting the one wire it has to ground on the terminal block but it still did not start / still on spark. PO had replaced the distributor so it is new. Boat ran great first 5 times. Now nothing. Any ideas?

 

[achris]

Hello and welcome aboard.

Can you tell us which ignition system you have? (Points or EST)

Assuming points, did you check there was 12v at coil+? Did you look to see that the points were actually opening and closing? Are the points clean and free from corrosion? When was the last time the points were changed?

Chris...

 

[alldodge]

Need to know what you have for ignition

 

[aidanmurphy]

I am not exactly sure but I do not think it is points. From what I can tell there is not a +/- terminal on my coil to test. Just two sets of wires coming out of the plugs. I will attach some photos of coil and dist

 

[alldodge]

That's a EST dizzy and check to see if it has 12v on the pink wire going to the coil.

Remove the connector and turn ignition on and measure

 

[aidanmurphy]

Yes, there is 12V at the purple connector with ignition on

 

[QBhoy]

Make sure she isn’t in gear too

 

[aidanmurphy]

Make sure she isn’t in gear too

Boat turns over but just won't start, this is why I don't think killswitch / safety lanyard or gear is the issue

 

[alldodge]

Going to bed will get back in morning. The in gear switch will keep it from cranking, the safety will keep it from starting but will crank

 

[QBhoy]

Boat turns over but just won't start, this is why I don't think killswitch / safety lanyard or gear is the issue

Most I’ve known will still turn over when they are interlocked

 

[achris]

Most I’ve known will still turn over when they are interlocked

Not Mercury factory wiring.. The 'in gear' protection switch has yellow/red wires, that's the cranking circuit. The 'deadman switch' has purple wires, that's ignition.

In gear still has power to the ignition but with not crank, deadman switch remove ignition power but still will crank...

Chris...

 

[alldodge]

12V to the coil, check
Need to check the distributor

 

[aidanmurphy]

12V to the coil, check
Need to check the distributor

Just did this test. I am getting no reading / infinite when testing either green or white lead to the dist housing. I don't have a X100 on my multimeter, but I set to x10 and receive a steady 200ohm between white and green.

 

[alldodge]

If your meter is good, then I would replace the coil (item 6)
https://www.mercruiserparts.com/bam/subassembly/30920/2330/50

Can find same part online but using part number

 

[aidanmurphy]

Thanks, will try and source that part this week and update back

 

[aidanmurphy]

Update: I replaced the pickup coil and motor still turns but wont start up. Hooked up inline spark tester between distributor and ignition coil and there is no spark still. Any ideas?

 

[1960 Starflite]

Just something that happened to my 1979 "140". I did most you have covered. Anyway right to my point. Mine has glass fuses, discovered I had voltage at coil until I cranked it. Under load voltage at coil quit. Pulled the ignition fuse, cleaned corrosion off of the ends, replaced, all is well.

 

[aidanmurphy]

Just something that happened to my 1979 "140". I did most you have covered. Anyway right to my point. Mine has glass fuses, discovered I had voltage at coil until I cranked it. Under load voltage at coil quit. Pulled the ignition fuse, cleaned corrosion off of the ends, replaced, all is well.

Thanks for the insight, you are speaking of the 15-20AMP fuse? Mine has the fuses on the dash if that is what you mean. I will check that as well

 

[alldodge]

Thanks for the insight, you are speaking of the 15-20AMP fuse? Mine has the fuses on the dash if that is what you mean. I will check that as well

No reason to check the fuse because u said it had 12V at the coil

 

[aidanmurphy]

Yes, I have 12V at the coil. Also my tach is disconnected at the dash to rule that out.