Mercruiser 165HP ignition problem FRUSTRATING!!!

[NickWolf86]

After spending countless hours not only troubleshooting, but searching the internet, including this site, I find myself ever the more frustrated by the minute. Here is my issue:

I have a 1968 Tom Sawyer 19ft with a Mercruiser 165hp. When I turn the key over, everything gets spark up to the coil, which has plenty of power, and puts of spark. The problem is that no spark is coming out of the plugs! I took the cap off, cleaned everything up, and replaced the condenser and a rotted, exposed wire. When I put it all back together, a plug had spark when grounded to the block. As soon as I put the plug back in and tried to fire it, NOTHING. Now, not only is there no spark from the distributor, but intermittent spark from the coil. I am very much car engine savvy, but this is giving me, and a mechanic brother-in-law, a HECK OF A TIME!!! Please help!

Any help or advice would be appreciated, and on the verge of reward-worthy

Thanks,
Nick

 

[rlpolo101]

Re: Mercruiser 165HP ignition problem FRUSTRATING!!!

I had the same issue for awhile. I took the cap off and ran fine grit sand paper between the contacts on the points (it gets fouled up too) and she fired right up after that.

 

[ziggy]

Re: Mercruiser 165HP ignition problem FRUSTRATING!!!

have ya tried replacing the ign. parts?

i give my 165 a tune up every spring. on the electric side this includes replacing... .

points
condenser
cap
plugs (gap new plugs)

then set dwell

then set timing

what wire got replaced?

have ya read #16,17 and 18 from the adults only sticky?

my batt. also gets load tested at the local napa store.

 

[JerryIrons]

Re: Mercruiser 165HP ignition problem FRUSTRATING!!!

Don't forget a new rotor as well.

I don't have much experience with a boat, but I had a coil go bad in my truck that would spark a plug on the block, but when under compression could not spark a plug. I stared at the engine for 3 days trying to figure out what went wrong and finally decided to put a new coil in. Which by the way looked fine until I removed it and saw a fine crack on the bottom of it. From what I have been told boat coils do not go bad that often, and when they do you can tell by looking at them (leaks oil or something like that).

You will get this fixed there are only so many things that can go wrong, it is all a process of elimination. There is a sticky on ignition check it out.

 

[Don S]

Re: Mercruiser 165HP ignition problem FRUSTRATING!!!

Might want to visit HERE and take a look at items 16, 17, and 18. Especially #17.
Then you won't be throwing parts (aka money) at it by replacing good parts in hopes of fixing the problem.

EDIT: Guess I should have read the other reples first. Oh well, I do work work at the Department of Redundancy Department ya know.

 

[ziggy]

Re: Mercruiser 165HP ignition problem FRUSTRATING!!!

Don't forget a new rotor as well.

yep, R&R that too. i knew i forgot something...

Oh well, I do work work at the Department of Redundancy Department ya know.

good things said deserve repeating sometimes...

fwiw, ya might have a look at your elec. system running at night. if your coil is leaking electricity the light show will be very evident at night..

 

[dbkerley]

Re: Mercruiser 165HP ignition problem FRUSTRATING!!!

Be sure you check the resistance across the coil. The 6 cylinder should be reading above 3 ohms. If not, you may need to add a ballast resistor. The other thing is the battery. All may seem and test fine when it is just sitting there. However, when that starter throws the load to it, it may not have quite enough left to crank fast enough to fire. Try a jump start with good cables first and then see where you are.

I left the timing light connected to mine for days while I tinkered with it so I could see if I was firing to the plug or not and found that the fire to #4 was somewhat erratic at idle.

I have made offerings of an electric choke, Pertronix electronic ignition conversion, new plugs, wires, cap, rotor, 1000cca battery, seafoam treatment, and several other things I forget right now trying to appease the ignition blues gods. Everything is good right now.

I get anal about these things some times. I want to back down the ramp in 40 degrees - hit the key one time and back it off. I refuse to sit and spray starting fluid with the doghouse off telling everyone "Hey, it is an old boat you just have to do these things." Keep a top notch tune on her and you shouldn't have any problems.

I wish it had an OBDII ECU that I could just scan and go. I had to go way back to old school after getting mine. If you can remember Bosch mechanical fuel injection, you'll be just fine.

 

[NickWolf86]

Re: Mercruiser 165HP ignition problem FRUSTRATING!!!

Many thanks for quick replies! I am going over to play doctor today, and see if I can finally get this beast to fire! I'll also get some pics to put up for everyone to see how rough my project is. I'll let you guys know how I do with the starting issues.


Thanks agai!
Nick

 

[JerryIrons]

Re: Mercruiser 165HP ignition problem FRUSTRATING!!!

yep, R&R that too. i knew i forgot something... good things said deserve repeating sometimes...

fwiw, ya might have a look at your elec. system running at night. if your coil is leaking electricity the light show will be very evident at night..

Yes that is good advice, I found a bad coil on another truck that was VERY obvious in the dark. Can you say Jacob's Ladder!!!

To the op, how did it work out?