Thunderbolt IV Spark Advance

[FreeBeeTony]

I am not convinced that my "Bogging" problem is fuel related anymore. (see previous post )It seems that no matter how I "Tune" the carb I can't get past ~3200RPM's.<br /><br />I plan on checking the advance with a timing light. I am going to put a piece of tape on the vibe damper with additional marks on it so I can monitor the advance as the RPM's increase and see what happens when the "Bog" occurs.<br /><br />How does the Thunderbolt IV advance the spark? I know it's done electronically, but how does it "sense" the RPM's? Through a pick-up in the distributor? Is there a rev limiter?<br /><br />I am going back down to the boat now and check the advance under load. I hope I find it retards for somereason at 3200RPM's.

 

[Bondo]

Re: Thunderbolt IV Spark Advance

(1)Through a pick-up in the distributor? (2)Is there a rev limiter?<br />

(1) Ayuh,........<br /><br />(2) Nope......<br /><br />Sure hope you find an Issue Tony,....<br /><br />It's got Me baffled......

 

[FreeBeeTony]

Re: Thunderbolt IV Spark Advance

I am trying to find a new sensor......noone has it in stock

 

[newport dave]

Re: Thunderbolt IV Spark Advance

FreeBee,<br />I didn't read the whole other thread, but have you checked for an exhaust restriction?<br /><br />Dave

 

[FreeBeeTony]

Re: Thunderbolt IV Spark Advance

yup.....been there/done that..........flappers are free!!

 

[waterone1@aol.com]

Re: Thunderbolt IV Spark Advance

Tony, it has been my experience that if the pickup in the distributer is bad, the engine either won't start, or misses badly or intermittantly cuts out. I have never seen one work fine at idle and up to 3200. Maybe someone else has ??? Just hate to see you throw money away if that isn't the problem.

 

[newport dave]

Re: Thunderbolt IV Spark Advance

Like Bondo said, there is no rev limiter in the Tbolt IV module. The ignition advance curve will depend on which module you have. It should say on the module. There also is no knock sensor on Tbolt IV to retard timing. The advance curve below is for V8-22a module.<br /><br />Dave<br /><br />

 

[FreeBeeTony]

Re: Thunderbolt IV Spark Advance

Is it possible I have the wrong module installed into this engine? Remember I just bought this boat.<br /><br />Can anyone tell me which module I should have installed? Which P/N? <br />The one in the above diagram is not for my engine.....I have a 350 Magnum.

 

[FreeBeeTony]

Re: Thunderbolt IV Spark Advance

Thought of something else.........I think I heard the prob;em tonight at th dock. I was reving it in neutral.

 

[FreeBeeTony]

Re: Thunderbolt IV Spark Advance

The number on my module 1H29A V824S.<br /><br />Do the numbers mean anything to anybody?

 

[newport dave]

Re: Thunderbolt IV Spark Advance

This is the advance curve for the V8-24s module, which I believe is the correct module for that engine.<br /><br />Dave<br /><br />

 

[FreeBeeTony]

Re: Thunderbolt IV Spark Advance

After around the 2200RPM point I didn't see much more advance, I don't think.<br /><br />Is it possibe there is something wrong with the module?

 

[prockvoan]

Re: Thunderbolt IV Spark Advance

Did you find an answer to your problem?

 

[cneste]

Re: Thunderbolt IV Spark Advance

Hello FreeBeeTony ,<br /><br />I havent read your entire thread so this might not apply,I am short on time, but I had the same problem where I can not get past 2300 rpms on a 1988 4.3 /alpha set up. I sent an email to a boater with the same problem last year and he responded back below.<br />Chuck<br /><br /><br />Yes, the problem was the spark plug wires. I also replaced the distributor cap and rotor. hope this helps<br />dave<br />-----Original Message-----<br />From: Chuck & Diane Neste <br />Sent: Sunday, June 19, 2005 10:27 AM<br />To: toth_d@<br />Subject: Boat Question<br /><br /><br />Hello Dave,<br /> <br />I came acorss your message posted on a boat forum. Did you ever resolve your problem? I have a 1988 rebuilt 4.3L and took it out for the first time yesterday. I can get my boat past 2300 rpms but out of the water on the trailer with ear muffs, I can get 6000 rpms.I have a brand new electric fuel pump with all filters new. My carb was winterized last year and was also bought new June of last year.<br /> <br />Thanks<br />Chuck<br /> <br />Thanks<br />My 1996 4.3L with 2bbl merc carb does not accelerate or come up to proper RPM's. this past weekend I could only get 3900 to 4000 RPMs versus the normal 4600 to 4800. When accelerating the motor lacks power. I replaced the plugs and cannister fuel/water filter, checked the Carb fuel filter (perfectly clean) and it still performed without power. Clymers says it could be the electric fuel pump or even the anti-siphon valve. any help would be appreciated in where I should look for the problem? thanks

 

[FreeBeeTony]

Re: Thunderbolt IV Spark Advance

That's about the only thing I haven't done yet and I intend to........replacing the plug wires.

 

[fede]

Re: Thunderbolt IV Spark Advance

Hi FreeBeeTony,<br /> i seem to have the same problem on my 1991 4.3lx , switched everything from one engine to the other (fuel line, carb, thunderbolt, coil ...) nothing.<br />Did you solve with the wires?<br />Fede

 

[imported_scott_m]

Re: Thunderbolt IV Spark Advance

In looking at the advance curve, it seems like most of the advance should be in by 2200 RPM anyway, so if you're not seeing much advance beyond that, would be normal. Not to jump on the plug wire bandwagon....I've kept up with your thread for a while now and really wish you the best of luck...Way back when I bought my wellcraft with bigblocks I was having some performance problems as well. Bogging, occasional pop in the carb, etc, and sure enough at some point someone had put auto-grade wires on the motor. Changed those out along with the full tune and she ran fine. Going back to basics...are you sure you do not have a wire crossed? These things will run great with two wires crossed. Also, have you tried removing the fuel cap while it is in the "bog" range?

 

[imported_scott_m]

Re: Thunderbolt IV Spark Advance

Oh and one more thing...two years ago when I was doing the tune on my wellcraft, the rotor had welded itself to the dist shaft and in trying to get it out, I broke the pick-up module for the ignition (merc 454 with t-bolt 4 ignition). Anyway, my local parts place seemed to have a lot of odd-ball parts...you might want to call these guys:<br /><br />JOA Boating Center - 770-945-0530<br /><br />Also, here in FL, I've found Brydes Marine in St. Pete to have a bunch of stuff, decent prices, and VERY helpful staff. If you're not finding what you need locally, you might want to give these guys a try.

 

[FreeBeeTony]

Re: Thunderbolt IV Spark Advance

When you broke the sensor....did it run at all?

 

[imported_scott_m]

Re: Thunderbolt IV Spark Advance

I did not even try to fire the motor with the broken sensor...it did come out in pieces. However, what I can tell you is that the sensor that was in there appeared to be a magnetic pick-up type of device and it was way corroded with rust and crap. If this is what passes the RPM signal to the advance module, I could possibly see how this corrosion could prevent the signal from getting there and therefore not allowing your advance to run up. But I'm not sure you're not seeing the advance..you did say it came in by 2200 which would seem fine. I think the sensor was about 70-80 dollars.