No Spark-3.0 Mercruiser 1988

[itstimz]

1988 3.0 Mercruiser w/ alpha 1 outdrive. 16' Thundercraft
eng ser # B849506
Outdrive seriel # OB943926
Manual used-Clymer # B742
New Starter
New battery
New ignition switch
New Coil (internal resistor- there is no external that I can find)
New Alternator
Project Boat

NO SPARK

After a long delay (12 months) I've gotten back into this project boat. I've followed the steps on page 49 fig 25 of the manual and it concluded that I have an "open between + (coil) terminal and battery". unfortunately, electrical issues are not my strong point. I do have a multimeter and I know how to use it. This is how I've tried to find the "open":

With the key off and negative multi lead at ground and I went around with the positive lead and touched all the connections (starer, slave. coil, safety switch, choke). The only ones that registered voltage were (of course) the primary to the starter and the red at the starter slave.

What else should I do to find this open? (by the way...what is an "open"? I think it is an open circuit with juice running thru it...is that correct?

!Muchas Gracias! in advance

Tim-Florida

 

[Don S]

Re: No Spark-3.0 Mercruiser 1988

Turn the key to the run position, you should have power to the + terminal on the coil.
You also need the proper coil, there is a resistor wire in the wiring harness instead of a ballast resistor.
If you have power to the + side of the coil, replace the points and condenser, the points are probably glazed over from sitting.
A broken wire would be a an open.

 

[Haut Medoc]

Re: No Spark-3.0 Mercruiser 1988

1988 3.0 Mercruiser w/ alpha 1 outdrive. 16' Thundercraft
eng ser # B849506
Outdrive seriel # OB943926
Manual used-Clymer # B742
New Starter
New battery
New ignition switch
New Coil (internal resistor- there is no external that I can find)
New Alternator
Project Boat

NO SPARK

After a long delay (12 months) I've gotten back into this project boat. I've followed the steps on page 49 fig 25 of the manual and it concluded that I have an "open between + (coil) terminal and battery". unfortunately, electrical issues are not my strong point. I do have a multimeter and I know how to use it. This is how I've tried to find the "open":

With the key off and negative multi lead at ground and I went around with the positive lead and touched all the connections (starer, slave. coil, safety switch, choke). The only ones that registered voltage were (of course) the primary to the starter and the yel/red at the starter slave.
The yellow/red wire should only have voltage when the ignition switch is in the start position.....
I'd look to see if you have the ign switch wired correctly....
RED = B(ATTERY
Purple = I(gnition) or run
Yellow/red = (S) tart


What else should I do to find this open? (by the way...what is an "open"? I think it is an open circuit with juice running thru it...is that correct?

!Muchas Gracias! in advance

Tim-Florida

No, an open circuit is exactly the opposite.....
Open would be like the "off" position on a light switch.....
Closed would be "on"......
If you do not have 12 volts at the Bat terminal on the ignition switch, I would look at the connection (large plug) where the two wire harnesses meet.......
Upon reading your post closer, I think you have your ignition switch wired wrong....

 

[whywhyzed]

Re: No Spark-3.0 Mercruiser 1988

[....

 

[96lt4c4]

Re: No Spark-3.0 Mercruiser 1988

points


I replaced them every year in my old 88 Four Wins with a 3.0 liter OMC

 

[itstimz]

Re: No Spark-3.0 Mercruiser 1988

Thanks everyone!

I will:

Double check wiring to ignition and slave
Replace points and condenser
check for volage at + terminal on coil
Remember what the heck "open" means in a circuit

Then post results.

Thanks again!
Tim

 

[itstimz]

No Spark-still 3.0 Mercruiser

No Spark-still 3.0 Mercruiser

1988 3.0 Mercruiser w/ alpha 1 outdrive. 16' Thundercraft
eng ser # B849506
Outdrive seriel # OB943926
Manual used-Clymer # B742
New Starter
New battery
New ignition switch
New points and condensor (.022)
New Coil (internal resistor- there is no external that I can find)
New Alternator
Project Boat

Tried all previous suggestions. Still no spark. I've checked the wiring diagragm in the manual and the boat appears to be wired correctly (with the exception of the ignition switch which is not listed for some reason in the wiring diagram.This is what I got:

With key off;

voltage to red and orange primary from bat to starter
voltage to red wire at starter slave
voltage to red wire at back of alt
voltage to orange wire at back of alt

With key in run position;

voltage to red primary from bat to starter
voltage to red wire at starter slave
voltage at + terminal on coil
voltage at purple/yellow at starter
voltage at purple wire at choke
voltage to red wire at back of alt
voltage to orange wire at back of alt

Ignition switch;
there are 3 posts at back in an offset "Y" configuration. (if the "y" is up 2 posts oppose ea other and one post is offset to the left on top. The bottom of the "y" has an orange wire and is directly opposed by a purple wire and the offset to the left post is yellow. It seems to function fine. Engine cranks strong at "start" position and stops cranking in the "run" position. I tried switching the 2 top wires (yellow and purple) but when I turned the key to "Run" it started cranking (I switched the wires back). I checked ohms on these 3 wires. The yellow and purple went all the way to 0 but the orange wire only went 1/2 way up the meter.

Anyone have any ideas? Does that ignition wiring sound correct?

Tim
941-962-5140

 

[Windykid]

Re: No Spark-3.0 Mercruiser 1988

Take the points back out and sand clean the fly weights and points plate. Reinstall, adjust gap and dwell. If that doesnt work replace condensor.

 

[itstimz]

Re: No Spark-still 3.0 Mercruiser

Re: No Spark-still 3.0 Mercruiser

Did That-didn't work.

In fact I replaced the points and condensor. I cleaned the point surfaces prior to installation to ensure any shipping grease was removed. Set to .022 per manual.

Have voltage to the + coil terminal but no further. (changed coil fron internal resistor to external).

I partially unwrapped the wiring harness that runs along the head and counted 11 wires with only 9 exiting. I am assuming that the 2 extra (both light purple) are the external resistor wires as they get rather warm when the key is in the run position.

I am totally stumped and I'm sure it's something obvious and stupid.

 

[Bondo]

Re: No Spark-3.0 Mercruiser 1988

Have voltage to the + coil terminal but no further.

Ayuh,....

You should have voltage from the (-) coil to the Points, when they're Open.......

 

[Bondo]

Re: No Spark-still 3.0 Mercruiser

Re: No Spark-still 3.0 Mercruiser

Ayuh,.....
This is getting Ridicules......

Why are you running 2 threads that appear that you're C&Ping between them.....

Let 1 of them Die......

Are you Expecting Twice the Answers because you're running 2 Threads,..??..??

 

[CharlieB]

Re: No Spark-3.0 Mercruiser 1988

12V to the + side of the coil with the key turned ON

Measuring voltage on the - side of the coil fluctuates on/off as the points open/close

Disconnect the distributor wire from the - side of the coil and measure, no reading, defective coil

Get the 'correct' coil, recheck, then reattact distributor/points wire, crank and check spark.

 

[Don S]

Re: No Spark-3.0 Mercruiser 1988

I just put both posts in one. DO NOT start a third, it's almost impossible to figure anything out when you have 2 threads going.

 

[itstimz]

Re: No Spark-3.0 Mercruiser 1988

apologize for the double threading. I got a little mixed up in replying. won't happen again.

About the coil/external/internal resistor. Am I correct that I should be using an external resistor coil because the 2 additional lt purple wires in the harness are actually the the "resistor wires"?

Thanks and sorry!
Tim

 

[Don S]

Re: No Spark-3.0 Mercruiser 1988

How (Exactly) are you checking for spark. Be very specific.

Also, on your ignition switch, look very closely, there are letters there by the terminals. What wires are hooked to what terminal.
IF, you don't have any letters on that switch, then get another switch that has them.

 

[itstimz]

Re: No Spark-3.0 Mercruiser 1988

Checking for spark:

I am removing a plug and grounding the threads. then i will crank the engine and look for spark at the plug.

Also removing the coil wire from the distributor cap and holding it about a 1/2 inch from a ground and cranking the engine to check for an arch.

I will double check the ignition switch tomorrow and change if necessary (Florida weather permitting!).

I greatly appriciate your help!

Tim 941-962-5140

 

[JustJason]

Re: No Spark-3.0 Mercruiser 1988

hows the cap and rotor look??? with the cap off crank the engine and make sure the rotor spins.
What happens if you hold the high tension cable 7/16ths of and inch from ground? try that, and put a test lead on the negative side of the coil and tap the test lead to ground rapidly.

 

[Don S]

Re: No Spark-3.0 Mercruiser 1988

If the coil wire is bad, the rest of the wires will have no spark either.
Use one of the other plug wires, put the distributor end of the wire in the coil, and a screwdriver in the plug end and of the wire and hold the shank of the screwdriver near a clean ground. Then give it another try.

 

[Coors]

Re: No Spark-3.0 Mercruiser 1988

I just re-read his post, and saw the magic word CLYMER .
You need an OEM manual.

 

[Maclin]

Re: No Spark-3.0 Mercruiser 1988

How did you check the points setting?

I am inline with Charlieb's thinking here for troublshooting. Read his post again.

I would want to connect a dwell meter to the negative side of the coil and watch it as you crank. It should try to register something.

If no dwell meter then a voltmeter with negative lead hooked to ground and positive lead hooked to the negative coil terminal should fluctuate between 0 and 9 volts or so as you crank. Leave all wires on the coil hooked up for this test.

Knowing what goes on at the negative side of the coil will tell you if the coil is receiving good "signal" from the points. If the negative side shows pulsating activity then the problem is in the secondary voltage system which is the rotor, cap, coil wire and plug wires. Oh, and the coil itself. Maybe the rotor is not matched to the cap. I am not sure what all is different now than when it was running before.