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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3938
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have one MARINER 150 CV 6 cylinders of 1993 with 450

Customer Question

I have one MARINER 150 CV 6 cylinders of 1993 with 450 H.Today the engine does not take any more its tours(towers,ballots) and no déjauge not any more. Test compression: OK, changed candles, reels, gas pump, carburetors, fuel filter, all the radiator hoses
and pear and 2 CDI. Could you help me before I set fire to it? Thank you. Didier.
Submitted: 2 years ago.
Category: Boat
Expert:  Charles replied 2 years ago.

Hello, my name is***** will assist you today.

I think that we may have a bit of a language barries here. I am going to try and get you thru how to repair the engine. Please let me know if I am off on a translation.

450H = 450 Hours

towers = throttle

candles = spark plugs

reels = reeds

pear = water pump

Now after all that, what was the compression numbers that you got on the engine?

Has the boat been sitting for some time?

Customer: replied 2 years ago.
Hi Charles,
Thanks for your answer and i feel good if you can help me.
Sorry for my english, i am french of New Caledonia.Reels = ignition coils
If i remember, i think between 7 an 8 to all cylinders.
No, the boat have not been sitting for a long time. There's no cold winter here ! No sleep in winter.
But there's a few months that my outboard is out of use and i try to work on just on week-ends (1 or 2 week-ends in a month).
In fact, i change a cdi there's 6 months and the boat goes well. Just two rides. And now, i have the same problem, like not enough gasoline to go ! I put the command completely, and the motor stay between 2000 and 2600 rpm (?).
Waiting for your answer.
Expert:  Charles replied 2 years ago.

Dider, do you have a multimeter to do some testing?

Is so start the engine on a hose. Test the voltage on the switch box on the red and the red/white wire. You should be getting 25+V AC at idle and it should come up from there as you increase the RPM. Does yours do this?

Customer: replied 2 years ago.
Hi Charles,
Yes, i have a multimeter.
I'll do these tests on saturday because my boat is up to 100 kms from my home (secondary home).
If you think i have some other tests to do , please tell me before friday.
However, i had planned to work on my mariner this week-end.
Waiting for you.
Expert:  Charles replied 2 years ago.

Also test the blue and the blue/white wires on the switchboxes as well. These are cranking or running tests. On the Blue wires it should be more than 180V AC

Customer: replied 2 years ago.
Hello Charles,
I test like you ask me :
on the red/white : no really good AC; there was a - for the value ! tested in 20 V AC and 200 V AC !
on the blue/white : idem !
I test all my six sparks plug (again) and i find that no spark (no fire) on cylinder 1;3 and 5. The engine goes just with tree cylinders (the left side, if you look cylinders in front of you). I decide to take off the sparks plug and test them outside (with ground) and no arc, no fire.
I decide to change the stator. Done. (I have bouht a few months ago an marine 175CV for used parts !)
When i plug the 4 yellow wires to the two voltage regulator under the ignition coils, one yellow wire was burn. I change the electric limestone and plug the yellow wires correctly (I have not changed the voltage regulators). Like all wires are yellow, i thought there is no sense to plug them.
I test again the switch boxes :
Red/white : 18 V AC (maximum)
Blue/white : 88 V AC at 3000 rpm approximatively.
I specify that the numbers on multimeter are like crazy. For the red/white, example, you read 18 and 2 and 7 and.....) Perhaps this normal ?
I specify too i have no changed the trigger and the idle stabilizer !
I test the sparks plug : no fire on cylinder 1 and 5. I win the 3 !!!!!
I work with wiring diagram of 150XR6 models.
I shall be very happy if you can solve my big problem !
Customer: replied 2 years ago.
Sorry Charles, i forget a question about the igition coils.
How can i test the ignition coils ? With a multimeter ?
Thanks for all.
Expert:  Charles replied 2 years ago.


Swap he position of the switch boxes. If the problem goes to the other side, replace the boxes as a pair.

Customer: replied 2 years ago.
I already swap the position of the switch boxes !
Customer: replied 2 years ago.
when i swap the position of the switch box, the problem of the tree cylinders on the right side was the same !
Expert:  Charles replied 2 years ago.

Ok, Remove the black/yellow wire from that switchbox. Test for spark again.

Did you test the voltage on the blue wire as well as the blue/white?

Customer: replied 2 years ago.
NO, i forget to test the blue wire on the inner switch box.
Ok for testing without black/yellow.
And about ignition coils, no test ?
Customer: replied 2 years ago.
All these tests just this saturday or before if i can go early.
No other tests to do ?
And if black/yellow disconnected and spark, what does it means ?
Expert:  Charles replied 2 years ago.

The coils is just a resistance test. It would be so odd for all 3 to so out at once. If you get spark back with the black/yellow off, the problem is in the boat or the harness.

If you get over 180V on the blue/white, the stator is the issue.

Customer: replied 2 years ago.
88 V on the blue/white actually, what does it means ?
Sorry, but i would like to understand ! To do some tests it's OK but undestanding the way, i feel good.
However, i agree with the fact that ignition coils failed at once, it would be very odd !
Expert:  Charles replied 2 years ago.

In order for the switchbox to send the correct voltage to the coils to fire the plugs, they need 180V AC. Your stator is just not putting that pout any more. replacing the stator will get the engine running again.

Customer: replied 2 years ago.
OK, i understand that.
Like i say before, there's a faw months ago, after working on switch box and carburators and gasoline pump, then my motor runs very well !
And after tree or four trips, having fishing party with friends, and stop the engine and start for several times, i stopped on a island to swim and barbecue. In the afternoon, i started the engine to go home and suddenly, the same breakdown.
I changed the stator (used part from mariner 175) and this engine was good and runned very well. Just the bottom of the engine was broken. It seem odd to have the same breakdown on the two stators, is'nt it ?
Expert:  Charles replied 2 years ago.

When that happens, you have a short in the switchboxes. That is the only thing that will fail the stator like that.

Customer: replied 2 years ago.
short ? i don't understand
you mean shoot ?
Expert:  Charles replied 2 years ago.

A bad wire internally inside the switchbox that is leading the power from the stator to ground. This would cause the stator to fail repeatedly on the same side.