1990 Rinker 18.6

[ibrw1]

My neighbor just bought the boat listed above. It has a 2bbl 4.3 MerCruiser. He says it wouldn’t start. So I connected my timing light, hit the starter, nothing, no flashing. Also no fuel either. Boat has a new fully charged battery, in fact, almost everything under the swim deck seems to be recently replaced. Spark plugs, spark plug, wires, distributor, cap, new coil, on and on, I guess throwing money at it doesn’t always mean success, lol

Where is the best website to go to get the wiring diagrams? I found several wires disconnected and taped up.

He paid a grand for it, the boat looks extremely well taken care of, the trailer as well. My guess is the previous owner had some sort of issue and he hired some dumb guy to resolve it.

 

[matt167]

Check the points. Verify 12v to the + side of the coil. Look at what you have.

 

[ibrw1]

Yeah, it had 12vdc

 

[matt167]

Clean the points. If it’s got a pertronix ignitor, it’s probably bad. If it has a Delco EST, it may be wired wrong

 

[nola mike]

Clean the points. If it’s got a pertronix ignitor, it’s probably bad. If it has a Delco EST, it may be wired wrong

That engine should be TB4, no points. Check the stickies for the troubleshooting guide.

 

[ibrw1]

Clean the points. If it’s got a pertronix ignitor, it’s probably bad. If it has a Delco EST, it may be wired wrong

No points, electronic ignition, ordered replacement

 

[Scott Danforth]

Where is the best website to go to get the wiring diagrams?

you wont find a wiring diagram for the boat.

It NEVER existed.

however the factory engine service manual will have wiring for the motor/controls/and required gauges in it.

you can get factory service manuals for the mercruiser via https://publications.brunswick.com/

 

[ibrw1]

So, it has a Mercruiser thunderbolt lV V6-14
I, like a NumbNut did not check is the Coil was wired correctly. I will asap. If I could get a drawing it sure would help. I understand that it may not exist, bummer. Anyway, no spark. I have a suspicion that this boat actually sank.
Somebody spent a lot of time replacing just about everything in this boat, mechanically, and electrically anyway. I found water in the oil I found water in the glove compartment. Everything seemed to be wet. I’m not concerned with cracked block or anything like that because it’s a couple days worth of work. I replaced some milkshake motors in the past. I found the shift bellows had a hole in it. I have a really nice garage. I got three boats in there right now. I got all winter long to get these things done so it’s no big deal.

 

[Scott Danforth]

in the stickies is a thrunderbolt troubleshooting guide

 

[ibrw1]

That engine should be TB4, no points. Check the stickies for the troubleshooting guide.

Yes, TB4. Thanks! I'm going to hopefully fix it Friday night, Chicago Marathon is Sunday so this weekend is a mess.....

 

[2004 searay]

also check the tach, if the tach is dead, it shorts out the coil, disconnect the grey wire from the coil and if it starts, you know the tach is dead,

 

[ibrw1]

Yes, TB4. Thanks! I'm going to hopefully fix it Friday night, Chicago Marathon is Sunday so this weekend is a mess.....

Had delay to fix, just got back to the project.

Please excuse my ignorance, but I haven’t any idea how to get to a stickies for troubleshooting.

I disconnected the tachometer as a test. No change.

Anyway, when I turn the key to on, 12 V appears on the plus side of the coil.

I ohmed the coil.
Primary .7 ohms Secondary 9K ish.

I have several Fluke 87V meters connected.
One is connected to plus side of the coil and ground.
The other is connected to minus side of the coil and ground.

I turn key to on they both go to 12v, I turn key to start they both fluctuate between 8 1/2 to 10 V DC.

So, a little of my background history in 1974 when I was a junior in high school I got a job repairing TVs in people’s homes. Since then I received 3 degrees in electronics and I would fly all over the planet, repairing computer systems, motor drives like that. I guess what I’m trying to say is I’m no genius but I do know my way around test equipment.

So my next move was to connect in a dual channel oscilloscope to both the plus side of the coil, plus and minus sides. both of the signals were pretty much exactly in sync so I can understand why there isn’t a spark.

I did replace the thunderbolt 1V module. No change. Guessing

If I disconnect wires on minus side, then jump to ground then I should get a spark. Is this a valid test? Is there something missing that provides a
Signal for the TB4?

I have a blue and white wire that I’m 99% sure is to capture the water temperature. The blue and white wire doesn’t go anywhere. It was taped off.

 

[ibrw1]

Had delay to fix, just got back to the project.

Please excuse my ignorance, but I haven’t any idea how to get to a stickies for troubleshooting.

I disconnected the tachometer as a test. No change.

Anyway, when I turn the key to on, 12 V appears on the plus side of the coil.

I ohmed the coil.
Primary .7 ohms Secondary 9K ish.

I have several Fluke 87V meters connected.
One is connected to plus side of the coil and ground.
The other is connected to minus side of the coil and ground.

I turn key to on they both go to 12v, I turn key to start they both fluctuate between 8 1/2 to 10 V DC.

So, a little of my background history in 1974 when I was a junior in high school I got a job repairing TVs in people’s homes. Since then I received 3 degrees in electronics and I would fly all over the planet, repairing computer systems, motor drives like that. I guess what I’m trying to say is I’m no genius but I do know my way around test equipment.

So my next move was to connect in a dual channel oscilloscope to both the plus side of the coil, plus and minus sides. Both of the signals were pretty much exactly in sync so I can understand why there isn’t a spark.

I did replace the thunderbolt 4 module. No change. Guessing it was ok? No way for me to tell?

If I disconnect wires on minus side, then jump to ground then I should get a spark. Is this a valid test? Is there something missing that provides a Signal for the TB4?

I have a blue and white wire that I’m 99% sure is to capture the water temperature. The blue and white wire doesn’t go anywhere. It was taped off.

Could it be the proximity sensor inside the distributor?

 

[ibrw1]

Could it be the proximity sensor inside the distributor?

 

[Scott Danforth]

The stickies are the few fixed forum threads at the top of all the forums. They are highlighted in yellow, have a little thumb tack icon

 

[nola mike]

Here:

How Mercruiser Thunderbolt ignition systems work.

Mercruiser Thunderbolt ignition systems. Mercruiser introduced the Thunderbolt IV onto their engines in 1982, alongside the introduction of the 1-R drives. The TB-IV system was used until the introduction of TB-V mid-way through 1996. Thunderbolt V was an improvement on an already exceptionally...

forums.iboats.com

You're reinventing the wheel. The module is NLA, how do you know what you replaced is good? Yes, the ignition trigger in the dizzy is a fairly common failure point though yours should be the upgraded sealed unit.

 

[ibrw1]

Here:

How Mercruiser Thunderbolt ignition systems work.

Mercruiser Thunderbolt ignition systems. Mercruiser introduced the Thunderbolt IV onto their engines in 1982, alongside the introduction of the 1-R drives. The TB-IV system was used until the introduction of TB-V mid-way through 1996. Thunderbolt V was an improvement on an already exceptionally...

forums.iboats.com

You're reinventing the wheel. The module is NLA, how do you know what you replaced is good? Yes, the ignition trigger in the dizzy is a fairly common failure point though yours should be the upgraded sealed unit.

I don’t know know if it ever was the problem. I do know that they are NLA and also I know about the new upgrade. The guy that I purchased the part from is willing to exchange for another but I hate to be one of those people wasting everyone time. I went after my best guess hoping that that was the part. I have a ton of test equipment if someone knew how to test bench test the device. Well that would be just wonderful. The guy that bought this boat doesn’t have much money so I certainly wasn’t going to guess for a $500 upgrade that could have nothing to do with whatever the problem is. I have a place on the Illinois river and on the weekends I fix boats for people for free. They pay parts. Anyway, I appreciate the info!

 

[ibrw1]

Just wondering, the PLUS coil goes to 12+ volts when the key is turned to start. MINUS coil goes to 9.5 volts. I'm using a 2 channel oscilloscope. No spark
I tested the coil and it’s good
I ran a new ground wire 10 gauge THHN from the Riser directly to the negative on the battery.
I took the distributor cap off the rotor, does turn with the engine. I went through a few pages of checks and procedures collected online.
I'm pretty convinced that the issue is with the Thunderbolt 4 V6-14 ignition module. Outside of that, ideas?

 

[04fxdwgi25]

Here is troubleshooting TSB on the TB4

 

[cyclops222]

ALWAYS know when to NOT do a major DIY job.