1985 Mercury Black Max 150 V6 not firing on one side

[dkpz64]

I have a 1985 Mercury Black Max 150 V6. I started it up this spring to find out that the starboard side is not firing. I unhooked the two yellow wires on the rectifier and started it up and they worked so I thought it was a bad rectifier. I replaced it and it didn't help. thought I got a bad one so I replaced it and still the same problem. No fire on the starboard side. Don't know what to do next. Just a thought, could it be old wiring from the stator.?. It ran fine last year when I put it to bed for the winter. Please help... Thanks

[Aaronhl]

swap the switchboxes

[dkpz64]

Do I need to switch all the wiring on both boxes?

[LakeFever]

These old motors if budget allows replace the stator and both switch boxes new. Also replace every single rubber line on the motor and clean the carbs. Switch to premix and delete the oil injection. You probably should inspect and possibly replace the reed valves too. This ought to make it run like a champ for another 30 years

[Jim Speros]

Switch box problems typically drop a cylinder or 2 of spark. They should be replaced in pairs as one can effect they other thru the bias circuit. The white black wire.
A stator typically will take all 3 on one bank. It is a good move to replace stator and switch boxes as mentioned above. Your chance of overcoming the problem on the first swing is great.

[LakeFever]

Once I got a dva tester it all started to make sense to me. These systems run on a range of voltage. A frequency basically. Over time they drift off here and there and yes while replacing onesy twosy usually makes it run again it won’t run great and because these old parts have drifted out of pitch ( music people? ) they will never run properly. Swapping all to fresh brings the symphony back to concert pitch and this helps all components last a lot longer because the voltage range is within spec so nothing gets over taxed or under powered and keeps things humming along properly so to speak.

It’s very frustrating when you replace one part only to have it fail prematurely or leave you stranded on the water only to face the same problem again. Throwing good money After bad and wasting time plus frustration etc. freshest is the bestest with electrics

[dkpz64]

I did the cards and did away with the oil injected system last year. Didn't trust that setup. Well I swapped the red/blue wires with the red-w/blue-w wires and the problem moved to the port side, some suggest the stator is bad. But I'm a little confused, I came across some info that said if you remove the two yellow wires from the rectifier and all cylinders fire like they should then the rectifier is bad. That's why I changed it to begin with. Am I missing something? If I change the stator should I change the trigger as well or not? Thanks for the help.

[LakeFever]

This is precisely why I suggest to change it all one and done. The rectifier has a minor role here as it basically converts ac to dc to charge the battery mainly. The stator is a whole jumble of activity that it sends to the spark boxes to unpack and transform into high voltage ignition power. When a stator starts to go out it sends the wrong electricity into your entire system and can cause failures of pretty much all electric devices. The rectifier being the canary in the coal mine in my experience.

Anyways forget trying to outsmart this stuff you’ll stroke out. Replace the stator and the spark boxes new and give it a try. Can’t hurt to replace the trigger too. New rectifier also wise even if it’s recent. Cheap part

[dkpz64]

Ok Just ordered some parts. Not to bad but bad enough.... I will keep you updated when I get them in and installed.

Thanks again for the help....

[skialot2]

Get yourself a DVA tester. They are cheap. Test all ignition parts. Replace everything that is out of spec.

https://www.amazon.com/Electronic-Sp...786520&sr=8-2#