Mercruiser 5.7 with V6-14 TB IV module??

komodo_goods

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Good morning,

I have a 1998 Sunesta 232. It currently has a 5.7 Mercruiser and TB IV ignition in it. I removed the DIZZY to drill out some broken cap screws, and it was running before I did this.

I believe the engine was swapped out by a previous owner. I have verified the block is from a 1987 to a 1995 SBC based on the casting number 19043638. The dizzy is back in, set to TDC (compression), and I can't get it to start; it will sputter every fifth or so try but not start.

  • Below is a list of what I know..
  • It has a TB IV V6-14 module in it but I seriously doubt the engine has internals to support it as it has a 2bbl and iron heads. BUT IT WAS RUNNING with this module.
  • has new BR6FS plugs in it (installed after dizzy removed)
  • New cap, rotor, and wires installed and running prior to dizzy removal
  • I’ve started the no ignition “T/S tree” and got to grounding the grn/wht wire step and checking for spark. I do get a spark each time I ground the wire.
  • The T/S tree calls for the ignition sensor to be replaced at this point but I’m skeptical.
  • I removed the ignition sensor while the dizzy was out of the boat and cleaned some rust off it, but I do not think I damaged it.
  • Do you think I should still replace the sensor?
My next step is to set it back to TDC and try to start over. I can smell fresh gas, so I know the engine is getting fuel but spark is just not happening.

I’m also wondering with the V6-14 module if I need to “seriously” advance the base timing BEFORE it will fire.

Any help is greatly appreciated.

Ken
 

alldodge

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If your ignition sensor doesn't have 3 wires on it then I would suggest replacing it. The older 2 wire sensors were hit and miss. This is why the 3rd wire was added to make a better ground connection
 

Scott Danforth

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regardless of the timing advance module

verify you are on TDC on the compression stroke, and not the exhaust stroke
 

komodo_goods

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If your ignition sensor doesn't have 3 wires on it then I would suggest replacing it. The older 2 wire sensors were hit and miss. This is why the 3rd wire was added to make a better ground connection
It does have three wires, two wht/grn and one wht/red
 

komodo_goods

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Mine has 4 wire actually. 2 wht/grn, 1 wht/red, 1 black

Also just tested the coil.
Primary is 3.1 ohms
Secondary is 9k
Should primary range be .6-.8 and could that be stopping ignition?
 

komodo_goods

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Ohm on coil. Threads are pretty stripped and I do not think it's a OEM coils
 

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Scott06

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if it worked before you pulled the dist most likely is it is mis timed. The V6 module will work fine to run And you don’t have to advance it more than your normal 10 degrees initial to get it to start. It will not give as much total advance but you can worry about that later. I tested my engine out on a stand with a V6 module, ran no issue.
 

alldodge

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You have the old style which is classified as a 2 wire
The kit comes with terminal connections to make it go from old to new style
 

komodo_goods

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OK so we're moving in the right direction.
I'm able to get the engine to run but only with starter engaged.
Issue was not getting fuel....that's another issue I'll tackle next.

In the mean time I believe the purple added wire from the starter to the + of the coil is not supposed to be there.

Can anyone confirm?
 

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alldodge

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TB 4 and 5 get full time 12V when key is ON or when motor is cranking.

So check to make sure your getting 12V full time
 

Scott06

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OK so we're moving in the right direction.
I'm able to get the engine to run but only with starter engaged.
Issue was not getting fuel....that's another issue I'll tackle next.

In the mean time I believe the purple added wire from the starter to the + of the coil is not supposed to be there.

Can anyone confirm?
Check the kill / Man overboard switch. ignition gets power off starter when cranking then switches over to purple wire when in run. Can verify by putting key in run, check for 12 v at coil positive terminal
 

komodo_goods

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Ok, so I verified that the coil has 12 volts present on the purple wire at the coil when cranking, and it is not present when the key is only in the run position. The kill switch appears to be working correctly, as it kills the blower alarm as soon as it is triggered.
 

Scott06

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Ok, so I verified that the coil has 12 volts present on the purple wire at the coil when cranking, and it is not present when the key is only in the run position. The kill switch appears to be working correctly, as it kills the blower alarm as soon as it is triggered.
What is the blower alarm? All the kill switch should do is interrupt 12 v ignition circuit from key to engine harness. I’ll see if I can dig up a helm digram
 

Scott06

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Attached is a helm wiring digram. It show the purple coming off the key switch thru the kill switch, then daisy chaining through the gauges to supply the alarm and then the purple ignition wire. you are likely losing the 12 v on the purple though the multiple connections. The alarm isnt to put on the blower it’s the low oil pressure that should be coming on when ignition is powered but engine is nit running. Somewhere between alarm 12 v + side and coil + you are loosing power. Chase it down with a volt meter . Common areas are loose and corroded terminals on back of gauges and cannon plug at engine harness.
 

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komodo_goods

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Ok, guys, I figured it out. Thank you for the assistance. I was missing the 12-volt constant on the coil. I found the wire and connected it. Now it's time for a carb rebuild.
 

Bt Doctur

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If it ran before you worked on it then review how you installed the dist.
Is the engine set for number 1 cyl on its compression stroke. On comp stroke, set timing indicator to "0" deg on the balancer. install dist with rotor facing to number 1 on the dist cap,then install dist
 
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