'86 OMC GM 2.5L

[soccerguy83]

I have an '86 OMC GM 2.5L that is in a '86 Stingray 190 SVC SS that I am trying to get running again after being properly laid up for 10 years.

I recently rebuilt the carb and replaced the water pump. Now I'm trying to get it started again. Using a good battery I was able to get it to turn over, but it wouldn't even think of starting. I tried a small burst of starting fluid in the carb with the same effect.

This took me to the electrical side of things. I replaced all four spark plugs, though they looked good, with the same effect. I pulled the number one wire off and tested the spark with one of the old but still great looking plugs with no spark. I then pulled the high tension lead off the distributor and set it up about 1/4" from a jumper cable lead from the neg terminal on the battery and still no spark. I then tested the resistance of the coil and both primary and secondary were testing within specs.

I then tested the pos side of the coil to the neg battery terminal with the key in ON and had no voltage showing on the multimeter. So I came here and read the various stickies. I'm now going to work my way back from the pos terminal to the key to find where I'm losing power. I'm really hoping it's something simple as I want to run the boat Labor Day weekend.

PS. I wish I had found this forum yesterday as I could have gotten a ton more done on it troubleshooting wise. Instead I washed and cleaned the boat from top to bottom. Damn for a 30 year old boat she is beautiful!

 

[Scott Danforth]

welcome aboard

did you clean the points? with the motor sitting for more than 6 months, the points will need to be cleaned (run your wifes nail file thru them)

you will want to reset your dwell and readjust your timing as well.

 

[soccerguy83]

Scott, thanks for the welcome, no I did not clean the points, though I plan on reseting dwell and timing as well. Need to get power to the coil first though.

 

[Scott Danforth]

run a hot wire from the battery to coil+ (simple enough to trace out)

clean points (points are what pulses the negative side of the coil)

crank motor

it WONT fire until you clean the points.

then once the motor is running, trace out the remainder of electrical gremlins from sitting. since the boat has been sitting for 10 years, pretty sure every electrical connector and connection will need to be attended to. start with the battery, work your way to the big motor connector, up to the ignition switch and back.

 

[soccerguy83]

Scott, will try that tonight!

In looking through the Sticky "Troubleshooting a Points Ignition" the description states to plug a spark tester into the high tension wire coming from the coil and ground using the clip, I haven't been able to locate a spark tester that would work with the high tension wire. All I see seem to be inline with the spark plug wires.

 

[Scott Danforth]

your spark plug wire is a high tension wire. anything over 600 volts is a high tension wire, and since the coil output is between 30,000 and 50,000 volts, that classifies.

dont overthink the points. every spring you will have to clean them to get the motor to run, set dwell and timing and you are good for the season. every 5 years replace.

 

[soccerguy83]

Understood on the spark plug wire also being an high tension.

My comment was related to this troubleshooting post:
http://forums.iboats.com/forum/engi...-how-to-troubleshoot-a-points-ignition-system
Specifically:
"***Checking for spark***

- Remove the coil wire from the center tower on the coil.
- Install spark tester lead in the center tower on the coil.
- Secure large alligator clip end of spark tester to good engine ground.
- Turn the engine over with the ignition switch at the helm and observe the spark tester.
- If there is no spark or weak spark (thin orangish spark) at the spark tester, there is an ignition issue.
- Disconnect the ONLY the grey wire(s) from the (-) side of the coil, keep all others connected. If you now have spark at the tester, the problem is a shorted tach wire or a bad tachometer."


Also, I don't think I'm over thinking the points, I will clean them tonight. I just know I'm not getting power to the coil, if I'm not getting power to the coil then there is no way power is getting to the distributor or plugs.

Not trying to be argumentative at all and I really appreciate the assistance! Just explaining, hopefully better, where I was coming from.

Tonight the plan is to clean the points, run a jumper cable from the pos battery terminal to the pos coil terminal, see if she starts. If so, then start working through the purple wire issues that could be hindering starting, with any luck (please keep your fingers crossed for me) it will be a connector that needs cleaning.

Also, not sure if its related at all or not, prob not, but when I have the key in ON and turn my accessories on, the light on the switch lights up but I am not getting power to either of my two VHF's. No blown fuses that I can find either.

 

[Scott Danforth]

I fully understand what you are referring to

hotwiring the coil bypasses most of the testing process (you will still need to get back to finding out why you dont have power to the coil, etc.) however until you clean the points, you wont have spark. infact you could ignore the points until they are cleaned and set with a hot wire from bat + to coil +, spark tester on the coil tower to block (assuming your batt - is connected to ground), take a wire from coil- and touch to block and remove. once you remove the wire, the collapsing field in the coil will discharge the coil and you will get a spark across your spark tester.

the points are nothing more than a switch to ground operated by the cam lobes within the distributor

not sure if your wiring issues with your radios are related, lets focus on making sure the motor runs first. you can sort out the wiring after.

 

[soccerguy83]

Ok awesome, I'm glad we are on the same page, thanks Scott!

I understand how the points work along with the coil, very nice PowerPoint on that in the stickies as well!

Agreed on getting the motor running then sorting out other issues, but I didn't know if it would be indicative of issues with the key or something else that might be related. Really was just throwing it out there as an issue that could be a symptom.

Still plan to follow the plan for tonight outlined above, will post back with the results.

This forum is already far ahead of the other BIG one when it comes to older boats, over there anything older than 10 years and you get crickets, thanks a bunch!

 

[Scott Danforth]

the key issue could be corrosion, could be bad wiring, could be broken wires

 

[soccerguy83]

So I made some progress tonight, though I don't have a running boat yet. I'm not sure what fixed some of my issues, but I cleaned all the connections at the main engine wiring harness. I also found a second wire that needed to be hooked up to the neg battery terminal. Between the two of these I got all of my electronics working! I also cleaned the points.

Also, I now have power to the pos terminal of the coil with the key in ON. I also have voltage showing on the meter when the key is ON and connecting the neg terminal on the coil to the neg battery terminal, which according to my shop manual is indicative of a bad coil. I took the high tension lead off the distributor and left it attached to the coil, then placed it less than a half inch from a ground and cranked the engine and no spark.

I have ordered a new coil.

At least now I know that if I get the motor running all other systems are good to go.

 

[Speak]

Nice strategy based diagnosis. You are so close to hearing it run. Maybe post a video for us to see her fire!

 

[soccerguy83]

Sure! I will also post some pictures of the boat when I can get to a computer tomorrow to resize them.

 

[soccerguy83]

No Title

Here are the pictures! Doesn't look too bad for a 30 year old boat.

I have some rust stains that I will get some Starbrite for at some point, but they are not a top priority for me at the moment.

 

[Scott Danforth]

terminal on the coil to the neg battery terminal, which according to my shop manual is indicative of a bad coil. I took the high tension lead off the distributor and left it attached to the coil, then placed it less than a half inch from a ground and cranked the engine and no spark.

I have ordered a new coil.

At least now I know that if I get the motor running all other systems are good to go.

did you make sure that the points open and close completely? you will read power on the - side of the coil with the points open, however if you use a test light, the current across the windings would be minimal.

 

[soccerguy83]

Scott, I think I have been thinking about this wrong.

Though I thought I had a good understanding of what was going on I clearly had not. I was thinking along the lines that if the coil was "upstream" of the distributor that I needed the coil to work for the spark to get to the distributor. I went back and read the sticky PowerPoint on How Points Ignition Systems Work. That isn't accurate, they both need each other in order to function properly. The battery supplies power to the pos side of the coil, then the neg side of the coil goes to the distributor and the points. When the distributor rotates, then opening and closing the points, there is then a pulsing of power going through the coil's primary windings. Now that pulsing of power is then magnified in the secondary windings of the coil and all that voltage has got to go somewhere. When the distributor then rotates so that it's in alignment with one of the plug wires the coil secondary windings let go of the voltage that has built up and sends it to the distributor that then sends it to the plug causing the plug to fire.

All this time, I was thinking to myself I don't get why Scott keeps going on and on about the damn points when I don't have fire coming from the coil. Dang I think I now owe you a beer. If I can get some time this evening I will look at the points a bit closer and see if they are operating properly. If the points are not opening and closing setting up the current flow in the primary windings then the secondary windings are getting no voltage and won't ever spark.

 

[soccerguy83]

Well tonight, I did what you suggested Scott, I adjusted my points to 0.019" as per my manual specs and she started! She only ran for about thirty seconds and I had to give a lot of throttle, but she ran on her own!!

I then got run off by a storm, but there is light at the end of the tunnel! Now on the next good day I'm going to look at setting the dwell better than just using a feeler gauge, setting the timing and then seeing if I need to do anything with the carb since I rebuilt it. Then I need to get a new battery for it (been using one out of my car), replace the tires and get my left turn signal working on the trailer.

Then she will be ready for the water Labor Day weekend!

 

[Scott Danforth]

You may gather I like beer. A good stout or porter.....

 

[soccerguy83]

I brew beer so we could work something out haha!

Next steps, adjust dwell then timing then carb in that order assuming I can get it running good enough for timing before carb?

 

[Scott Danforth]

Get it idling about 650 on the muffs to set dwell and timing.