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TaChOmEtEr problem!

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1980 Points Ignition vs 1986 Thunderbolt ignition:mad:
Is there a conversion I can buy and plug in to correct this problem?

Memorial Day weekend 1980 Sea Ray SRV 310 project;
Replaced Port 1980 454 Merc with a 1986 454 Mercruiser Straight Drive with thunderbolt ignition, plugged it in, Now;
Tachometer and Hour Meter won't work, Oil Gauge reads at top of Scale (Starboard engine all working Perfect):confused:
Was working perfect no issues with old port engine except for Oil leaks and Bad rod Bearings:D

What I did after install;
Hit the Port Side Key first time started right up with no issues at least on the Engine end; Running Port Side Dash Tachometer Reads Zero, Dash Hour Meter Reads Zero and Dash Oil Pressure Gauge is reading at the top of Scale (Engine off Key on reads about 35lbs), Port Engine still Starts and Runs Great not a miss, took it out anyways, jumped up on a plane, Idled perfectly back to the Marina and put her away:cool::cool::cool::cool:
 

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Just guessing, but suspect that your port engine harness is not hooked up correctly. Check hook up at both ends against your starboard engine.
 
if it was "all great" before the swap and now aint so keen, somethings gone south with the wiring.....the hour meter is independent of the engine harness so I'd be inclined to start at the instrument panel.....

the oil pressure gauge reading suggests its sender wire may have an issue as well.....they usually go Full Scale or Min depending upon the 'standard' used...last idea, is do you know what the '86' came out of - helm configuration??
 
Just guessing, but suspect that your port engine harness is not hooked up correctly. Check hook up at both ends against your starboard engine.

Only one plug clocking orientation
86 vs 80 are a match but, are they impedance matched?


I'll check Grounds, again, smear Grease in THE PLUG and all the Thunderbolt connections

Looks like Purple wire Key Switch to Tach or Key Switch could be an issue
 

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There's no frequency content on the signals in the plug so there can't be any impedance issue (unless the pins/sockets are corroded).

Guessing from your first pic, you have a single helm setup - which means the oil pressure sender and the coolant temp sender will be 'off' for a single station use....

And it appears you have a decent approach for finding the issue(s) with the tach & hour meter....just remember that each gauge needs TWO GOOD power connections...
 
There's no frequency content on the signals in the plug so there can't be any impedance issue (unless the pins/sockets are corroded).

Guessing from your first pic, you have a single helm setup - which means the oil pressure sender and the coolant temp sender will be 'off' for a single station use....

And it appears you have a decent approach for finding the issue(s) with the tach & hour meter....just remember that each gauge needs TWO GOOD power connections...

Ok, this is all good information

I'll R/R the Oil Sender :)

Temperature is reading appropriately :)

Found right hand dash Voltage diff from Left. So, R/R Starboard Alternator and now reading same voltage as Port, YAY! :)

Proved out the Gray wire today, Dash to Module, R/R and Lubed every wire connection I could find.

Looks like the Tach signal wire (Gray) is independent of the run circuit (Purple) wire. So, I assume the Tach function of Thunderbolt Module is a Secondary function to Ignition. In other words, The Engine shouldn't be Running when the Tach reads zero but, it is running rather well?!! Pretty Crazy, Huh?!! LOL!!!
I'll try another Thunderbolt module
 
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the purple wire is more commonly called the IGNITION circuit and yes it is independent of the tach lead....I doubt there is any good reason to swap the module.....if the coil fires and the tach shows ZERO, I'd suspect the tach or its wiring....if yours has the selector switch, cycling it thru a few full sweeps can help restore tach functions.....on the other side of the thought process - a bad tach can keep the coil from firing....just something to keep in mind...
 
the purple wire is more commonly called the IGNITION circuit and yes it is independent of the tach lead....I doubt there is any good reason to swap the module.....if the coil fires and the tach shows ZERO, I'd suspect the tach or its wiring....if yours has the selector switch, cycling it thru a few full sweeps can help restore tach functions.....on the other side of the thought process - a bad tach can keep the coil from firing....just something to keep in mind...

Agreed but, we'll R/R the Thunderbolt Module, anyways, see what happens and tell ya the results.

Another weird thing is no coil.

Be easier to understand If it did't run LOL!

I ran a wire over to the Starboard engine Coil Negative from Left Engine Gray wire at Plug and the Tach worked fine (Port Engine Off Key On, Starboard engine Running). Still need to Put a test light on the Gray wire position on module with the Gray wire unattached

So, with all that said; I'll most likely R/R to 1980 Points Ignition but, not yet, more to come



Is there Marine Equivalent to the Delco HEI Automotive Distributor?
 

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So, today, I checked the Signal from the Thunderbolt Module Gray terminal with the Engine wiring Harness Gray wire disconnected
I got nothing while engine running and Nothing Key on to off with engine off, Next ran a wire from the disconnected Gray wire of the Engine Harness to the Negative of the Starboard Engine's Coil and the Tachometers ran perfectly in Unison see youtube videos below.

Yes, I'll be replacing the Thunderbolt some how, haven't figured which way to go yet
Soooooo sad to see the ends of the Thunderbolt Saga so quickly :)
I suppose it's way of telling the Captain head back to a dock cause, I'm gonna fail!!!
Long time Tuner and First time User! Thank you all for readin and the power steering, wait here I'll be back real soon and stay tuned!

https://youtu.be/PW75zZb6Bag and https://youtu.be/VkdSuXg2ZiY
 
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There're a few.....personally, the Voyager's are OK but far from the 'best' - biggest objection is the advance curve is fixed and can't be altered..

whichever path you take, make sure the "chosen part" is marine rated (no vacuum advance).....
 
There're a few.....personally, the Voyager's are OK but far from the 'best' - biggest objection is the advance curve is fixed and can't be altered..

whichever path you take, make sure the "chosen part" is marine rated (no vacuum advance).....


Agreed!
I just notice in the picture a "vacuum advance", My Bad
There, fix it :)

Found one at Summit Racing (Marine) looks just like this one arced for 24 degrees and all aluminum housing $100 :)
I think that's the one, I'll look at it!
24 degrees is correct for my running at about 3500-4100 rpm, Right?
I'll set at 6 degrees. Oooooooh, that's close?!! I'm already maxed out at 30 degrees, correct?
Should be 28 degrees.
Ok, I'll set my ignition timing at 4 degrees! Perfect :)
 

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☆Update☆
Looking further into the possibility of missing parts:
The thunderbolt has a weird rotor with a cookie cutter like
Metal thing on the bottom which is alarmingly missing on mine
I bet dollars to Dougnuts; That's the problem!
 
Nope, lost that Bet :(
I really thought I had a simple solution but, Noooooooooooo!
Mine Has a metal disk, with slots in it and some kinda optical eye ...where the vacuum plate would be.
 
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Can the trigger wheel be replaced with conventional Points or Spit fire Electronic?
IF not the whole Mercruiser Thunderbolt ignition system is Junk! I wouldn't trust em any farther than my Dock line lol!

Well, anyways, R/R the Mercruiser Thunderbolt Control for another one I have and the result is; the same :(
Note: Found a NO-NO; the Wires between the Thunderbolt Control Module and the Thunderbolt Distributor are Aluminum core should be copper.
So, on to the Cure! Just to see if my next idea with the HEI would work, installed a sweet, 1980 HEI (Will Be Replacing soon for new) and the result is; Everything works GREAT :)
See Video; https://youtu.be/ajHrhJ-GMds
 
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I've never seen anything other than stock stuff (or aftermarket replacements) under a TB cap...

Never seen any AL wire in a factory harness so don't know what caused that...glad you have a solution to go forward with...
 
Never seen any AL wire in a factory harness so don't know what caused that...glad you have a solution to go forward with...

Yeah, the wires fell apart when I touched them and not apart more like fell into dust.
ALUMINUM WIRES; Something to look out for, Boys and Girls!

All things considered, The above Cure is temporary until I get time to R/R the Whole Engine wiring harness, Senders and Distributor to match the Starboard side engine :)
 
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