5.7 4v ignition module thunderbolt IV question

[kennycarter]

Have a 95 4v 5.7 mercruiser 4V in a 95 SeaRay. The distributor has the ignition module & one other sensor on it which I assume is a knock sensor. I have been told this is a thunderbolt IV, but read here it is a thunderbolt V?
The boat will spin but not start, it will spark only one time & the spark is short & red. We have replaced the coil.

We did the test on the flow chart (though perhaps not correctly) and believe the module is bad. Before it quit running altogether, it had shut down in the past, but after a bit always started back up.

We have been told the module # is replaced with 807264A01 ($570 from the dealer), but this will require cutting & splicing the wiring harness, as it does not plug in like the original.
So any way to be certain of the correct module, as we have been given 3 numbers already & restocking fees are expensive?
Or can we just replace the distributor & module with a complete aftermarket marine performance distributor, like petronics?
Thanks

 

[Don S]

Re: 5.7 4v ignition module thunderbolt IV question

Have a 95 4v 5.7 mercruiser 4V in a 95 SeaRay. The distributor has the ignition module & one other sensor on it which I assume is a knock sensor. I have been told this is a thunderbolt IV, but read here it is a thunderbolt V?
The boat will spin but not start, it will spark only one time & the spark is short & red. We have replaced the coil.

We did the test on the flow chart (though perhaps not correctly) and believe the module is bad. Before it quit running altogether, it had shut down in the past, but after a bit always started back up.

We have been told the module # is replaced with 807264A01 ($570 from the dealer), but this will require cutting & splicing the wiring harness, as it does not plug in like the original.
So any way to be certain of the correct module, as we have been given 3 numbers already & restocking fees are expensive?
Or can we just replace the distributor & module with a complete aftermarket marine performance distributor, like petronics?
Thanks

What is the serial number of your engine.
A Lot of "I have been told" comments, time to find out what your really have.

 

[kennycarter]

Re: 5.7 4v ignition module thunderbolt IV question

S/N engine OF586258 1995 350 magnum, alpha one, with 4v carb

 

[Don S]

Re: 5.7 4v ignition module thunderbolt IV question

Is your ignition module mounted on the distributor or the exhaust elbow?

 

[kennycarter]

Re: 5.7 4v ignition module thunderbolt IV question

ignition module is mounted on a bracket on the distributor along with a second electrical part.

 

[Don S]

Re: 5.7 4v ignition module thunderbolt IV question

805361T6 Is the part number you should have. You can go to the Mercruiser site here http://www.mercurymarine.com/parts-and-accessories/parts-catalog/#epc::model_find use your serial number and verify it yourself if you want.
Not sure what the number you posted goes to I can't find it listed, but it's some sort of conversion kit. Not what you want or need.

 

[kennycarter]

Re: 5.7 4v ignition module thunderbolt IV question

Thanks so much for the help & the catalog link.
I believe I started with that part number in the beginning & the rep checked:
The part a mercruiser dealership sent was 805361T3, ordered using our serial number, & it had the wrong numbers of pins & did not plug in. Ours has 8 pins. I read the catalog as being 805361T6 I believe.
Are these 2 different parts ? (sorry to be dense, but I can't believe its so hard to get the right part)

Since then the first parts store gave us a second part number, then the mercruiser tech line has given us another number, #806957T2, which was replaced by the number I had, according to 2 web searches I did.
Thats the reason I asked about using an aftermarket system, I am no longer confident of getting the right part and hoped I could find the right part here. or how to go to some other system, the restocking fees will get outrageous if nobody can agree on the right part number.

 

[kennycarter]

Re: 5.7 4v ignition module thunderbolt IV question

32 806957T 2 MODULE, Ignition (350 MAGNUM ALPHA) SN# 0F353691 & Up
23 805361T 6 IGNITION MODULE (260 - 5.7L ALPHA) SN# 0F273498 & Up

I can now see how I got 3 different part numbers from 3 different reps.
I think it is 805361T6.
The cover over air cleaner says:
Magnum 350 Alpha One
S/N engine OF586258
but I am concerned that the merc rep gave us the other number and that one is a $570 part!
any way to be sure which one it is???

 

[NHGuy]

Re: 5.7 4v ignition module thunderbolt IV question

see Don

 

[Don S]

Re: 5.7 4v ignition module thunderbolt IV question

Here we go again, trouble shooting without being able to see anything.
Your engine should have a Thunderbolt IV ignition system by the serial number you gave.
Problem is, I just added these two things together.

ignition module is mounted on a bracket on the distributor along with a second electrical part.

Ours has 8 pins.

Put those two items together, and you have a Thunderbolt V ignition that didn't exist in 95 and only has 5 pins, not 8.

Something is wrong, and I don't have a clue what it is or why.
Did you get the serial number off the engine, or off of some old paperwork.

 

[kennycarter]

Re: 5.7 4v ignition module thunderbolt IV question

Serial number is off the cover from over the carburetor, we are 2nd owner since 2001, & it was serviced by the dealer from day one, low hours when we got it. we have all the paperwork on it since new, I see a ticket for a warranty recall on the control box , but nothing else.
is there some other place stamped on the motor I should look at for the model number?

 

[Don S]

Re: 5.7 4v ignition module thunderbolt IV question

A digital camera does wonders if you can't see it.

 

[kennycarter]

Re: 5.7 4v ignition module thunderbolt IV question

Model number on motor is the same F586258, except I can't see the O at the beginning.

The original coil says thunderbolt IV, we tried the original & replacement coil on an old Mustang just to verify our findings that the coil was not the problem & it will run the car.

Based on the flow chart we have a bad module, we have run the tests 2 times & get the same readings.
Our module has a nippon denso number clearly marked, but the mercuriser sticker has faded till no numbers are visible.
Any way to figure out which one to order? Or any way to put an aftermarket system in here?

 

[Don S]

Re: 5.7 4v ignition module thunderbolt IV question

Error on my part, :redface: :redface: I was reading serial number wrong.

You are supposed to have TB5 and you are supposed to have this module.

806957T 2 MODULE, Ignition (350 MAGNUM ALPHA) SN# 0F353691 & Up. Everytime I looked at that serial number range I would somehow decide your number was 0F286258 instead of 586. :facepalm:

 

[kennycarter]

Re: 5.7 4v ignition module thunderbolt IV question

Do you know of any way to get a correct module, that is a direct plug in, instead of the replacement which requires splicing the wires?

 

[Don S]

Re: 5.7 4v ignition module thunderbolt IV question

Nope, but the OEM kits of anything usually come with all the parts needed to change things over, including splices. They typically include instructions too.

 

[kennycarter]

Re: 5.7 4v ignition module thunderbolt IV question

Thank you so much for all of your help. After paying to restock parts that dealers sent that were not right, & getting so many different numbers I was ready to replace it with aftermarket. Part is still very expensive, but I will give it one more try.
Will follow up & let you know if its the right part this time!
BTW thanks for all your postings of the flow chart to check the ignition system, they were a great help.

 

[Don S]

Re: 5.7 4v ignition module thunderbolt IV question

If it was my boat, the TB ignition would be gone. 570 bucks for a module is stupid. You can buy a complete Delco EST marine system for a lot less than that module alone costs.
The TB ignition is a fine ignition system, but lately the cost of repairs has gone through the roof. Those modules were only $150 a few years ago.

Example http://www.michiganmotorz.com/delco-voyager-marine-electronic-distributor-p-119.html

They worked great in cars and trucks, and Volvo still uses them on carbed engines.

 

[kennycarter]

Re: 5.7 4v ignition module thunderbolt IV question

Do I need to worry about the shift interrupt that I thought I read was on TB ignition system, or will this aftermarket kit take care of it? Since I have to splice anyway, I would rather go the most affordable way. Thanks again

 

[Don S]

Re: 5.7 4v ignition module thunderbolt IV question

The EST will work with the shift interrupt fine, the 3.0L has been using it since 1990. It does work different, but not much to change. Plus there is plenty of help here if you choose to go that way.