Wiring help...starting our new 385 stroker on test stand

[bomar76]

Need to run our newly built 385 stroker on the engine test stand.
We have a TB IV distributor and V8 (22 degree) module in it.
Ignition Module is the mount on distributor type.

Following the wiring diagram in:
Mercrusier Service Manual 17
Section 4 B
Page 4

1. I see the power wire (purple) going from positiv battery terminal to + terminal of coil (Purple) then on to connector pin 3 (going from left to right, looking down from top)
I did that.
2. From - terminal of coil I ran a wire to the 5th (left to right) terminal of connector.
3. Ran a ground from 1st terminal of connector to negative battery.

I am getting no spark this way, or various permutations of it.
Here are my concerns (have a raging cold so not thinking the straightest):

Merc wiring diagram shows only 5 terminals in connector, but there are 6.
So......which one is unused?
I have tried connecting the white/green (that would go to the shift interruptor) and white/red connectors (that would go to terminal 2)from distributor body and no spark, and disconnected the same results.

What I am asking for:
An explanation of how to hotwire the TBIV to run on the test stand....

Anyone?

 

[Don S]

Re: Wiring help...starting our new 385 stroker on test stand

An explanation of how to hotwire the TBIV to run on the test stand....

This is going to be complicated, so pay attention. Hook up the main battery cables to starter and ground. Then, from the positive terminal of the battery, hook up a jumper wire to the small + terminal of the coil.
That's it.
To shut off, disconnect the wire
Don't even worry about the main harness connector.

 

[bomar76]

Re: Wiring help...starting our new 385 stroker on test stand

This is going to be complicated, so pay attention. Hook up the main battery cables to starter and ground. Then, from the positive terminal of the battery, hook up a jumper wire to the small + terminal of the coil.
That's it.
To shut off, disconnect the wire
Don't even worry about the main harness connector.

LOL...man, I was way overthinking that!!!!
If it hadn't been for that connector that's exactly what I would have done...maybe too much Nyquil....

 

[bomar76]

Re: Wiring help...starting our new 385 stroker on test stand

Don- after mulling that over my question is:
Shouldn't the - terminal the coil run to the module somehow?
There is no wiring harness on this engine at all, gonna swap the old harness off the 5.7 when we pull it.

 

[Don S]

Re: Wiring help...starting our new 385 stroker on test stand

maybe too much Nyquil....

DO THIS NOW
1. Disconnect the battery cables
2. Shut off the water
3. Put your hands in the air and back away from the engine..... slowly and don't fall down.

Go back at it when you can think, watch oil pressure, watch cooling, and know if something is going bad or not. Go watch some fire works or something

 

[bomar76]

Re: Wiring help...starting our new 385 stroker on test stand

DO THIS NOW
1. Disconnect the battery cables
2. Shut off the water
3. Put your hands in the air and back away from the engine..... slowly and don't fall down.

Go back at it when you can think, watch oil pressure, watch cooling, and know if something is going bad or not. Go watch some fire works or something

As always, great advice from you

 

[bomar76]

Re: Wiring help...starting our new 385 stroker on test stand

OK, fresh start today...
What I am looking for is direction to jury rig the TB IV ignition system without a wiring harness installed on the engine so we can start and run it on the test stand.
The gauges are not an issue at all as the test stand gauges are hooked to the senders, and for tach I will use the timing light's tach function, so don't even need a tach lead.
Just need advice on what pins I must connect to on the Module connectors to start and run...and again, no harness at all, so no shift interrupt, etc.

 

[Don S]

Re: Wiring help...starting our new 385 stroker on test stand

Which wiring diagram are you looking at? Page 4F-4 ?

 

[Don S]

Re: Wiring help...starting our new 385 stroker on test stand

I think I see what your problem is, You are assuming the wiring diagram shows the correct wiring location. I wouldn't. You really need that small harness that goes from the module to hook up the distributor and the coil. You won't need the rest of the harness, but you do need that one.

 

[bomar76]

Re: Wiring help...starting our new 385 stroker on test stand

Pretty much what I suspected...the wiring schematic really doesn't show the correct pinouts.
OK, I'll see if I can borrow that section of harness of someone...the Baja this will be going in is a bear to get to anything past the carb.....it's all under the integeral swim platform so I don't want to try to pull anything off it untill it's out. The plan was to fire up new engine, get timing, carb, etc close, then pull the old 5.7 and swap the harness.

Thanks, Don.

 

[JustJason]

Re: Wiring help...starting our new 385 stroker on test stand

http://i58.photobucket.com/albums/g266/open_bar/90-869229_Page_1.jpg

does that help at all?

 

[Don S]

Re: Wiring help...starting our new 385 stroker on test stand

http://i58.photobucket.com/albums/g266/open_bar/90-869229_Page_1.jpg

does that help at all?

That's not for the Thunderbolt IV

 

[JustJason]

Re: Wiring help...starting our new 385 stroker on test stand

doh.... let me recheck

 

[Don S]

Re: Wiring help...starting our new 385 stroker on test stand

Trust me, that set of drawings don't go back that far.

 

[JustJason]

Re: Wiring help...starting our new 385 stroker on test stand

your right (as always...) hehehe the only diagrams i have for tb4's are the book ones... i can still post that if you need it though bomar

 

[juliolop]

Mine is Merc 305 2001 5.0L CID Carb 2BBl with ICM in riser, SN 0M322975, is this a TB V? or IV?
anyone has the schematic for the harness
thanks

 

[Fishermark]

Hi juliolop - it is necessary to start a post of your own rather than asking at the end of an old post. (I always know it is an old post when I see Don S responding!)

 

[GA_Boater]

Mine is Merc 305 2001 5.0L CID Carb 2BBl with ICM in riser, SN 0M322975, is this a TB V? or IV?
anyone has the schematic for the harness
thanks

Ask in your other thread. You need a harness or fakery to start it on the ground.