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Author Topic:   Johnson V6 Electrical
billnaco posted 04-26-2007 07:55 PM ET (US)   Profile for billnaco   Send Email to billnaco  
Hi. I'm a Whaler owner and a long time lurker to this forum which I find most excellent. I try to do most of my repair on the boat and motor but have ran into a problem with my 1994 Johnson 150 FastStrike. Back during the winter I began to get false low oil beeps, voltmeter not showing charge, and the tack would act up. Being an electrical engineer I pretty much assumed this was a problem and a failure with the voltage regulator. Also during this time period the motor began to be difficult to start but would start. After starting and just on plane it will shut down on me.

Day before yesterday I replaced the voltage regulator and rectifier and the beep has gone away, the tachometer is working and the battery is charging. Now the problem: When I just about get on plane [the motor] shuts down on me and won't restart for about 10 minutes. After that it will run fine. I also would like to know the stator resistance for my motor because the voltage regulator and rectifier I used came off a 2003 Johnson but all appears to be the same. Sure need help from you experts and thanks in advance.

jimh posted 04-27-2007 10:57 AM ET (US)     Profile for jimh  Send Email to jimh     
Your experience with the voltage regulator and rectifier on your Johnson V6 is similar to mine. I also had a failure and replaced the voltage regulator on my 1992 motor. I think it is a fairly common problem with these motors.

The oil alarm beeps were likely caused by the problem with the tachometer signal. The alarm circuit uses the tachometer signal to deduce the speed of the engine and then compare the frequency of that signal with the frequency of oil pulses from the oil mixing pump. If the two get too far out of synchronization the alarm circuit concludes there is a problem and sounds an alert.

As for your current problem with the engine shutting down just as you are about to get on plane, it is hard to say what that might be. Does the engine just shut off like your threw a switch? A sudden change like that may be an electrical problem. The 10-minute delay may be permitting a component to cool off and resume function.

Fuel could also be the cause. When an engine stalls as the throttle is advanced, it may be due to poor fuel supply.

Give some more details about the manner in which the engine is shutting down.

An important test to make when the engine shuts off and won't restart is to determine if there is any spark. I recommend you obtain an in-line spark tester. Use it to check each cylinder to see if there is spark present.

seahorse posted 04-28-2007 07:36 AM ET (US)     Profile for seahorse  Send Email to seahorse     
Because you had regulator problems, it would be advisable to remove the flywheel and inspect the stator for melted insulation from the power coil and the charge coils. You can also inspect the alternator coils for discoloration and possibly arcing. Remove the stator for inspection as you may find a pool of melted insulation underneath it. Most of the time this problem occurs from the use of wing nuts on the battery. As OMC and BRP has preached for over 20 years, use stainless steel hex nuts and lockwashers tightened with a wrench.

Be sure to use the service manual procedure and beg, borrow, or steal the special flywheel remover/installer to save you from painfull phalange damage. Replace the 5 mounting bolts also and torque them correctly.

The charge coils are the brown wires with various colored stripes and each should measure about 500-600 ohms. The power coil is about 45-75 ohms, as long as you know for sure that you have a '94 motor.

A bad or melted power coil can cause the motor to quit suddenly, then restart after cooling a bit, but an infrared sensor ( electric eye ) and/or the powerpack can do the same thing. The sensor is the cheapest thing to replace if you do the "throw parts at it until it's fixed" method of troubleshooting.

JMARTIN posted 04-29-2007 10:49 AM ET (US)     Profile for JMARTIN  Send Email to JMARTIN     
I have a 200 hp OMC and my tach has started going to zero at times. Everything runs fine. Sounds like I should have the mechanic check this electrical stuff out. Jeepers, more money. John
billnaco posted 04-29-2007 06:47 PM ET (US)     Profile for billnaco  Send Email to billnaco     
I think I might have made a mistake with the voltage regulator. The one I put on came off a 2003 Johnson 150 and I assumed (bad word) it was the same as my 94 because it fit, wires the right colors, etc.

Guess I'm going to have to take it to a repair shop. You folks are great and if you have additional suggestions I'd love to hear them.

aja posted 05-02-2007 12:53 PM ET (US)     Profile for aja  Send Email to aja     
ARGH!! This sounds exactly like the problem I was having with our 1991 Johnson 150HP V6 a couple of years back. It generally ran fine but would occasionally do exactly what you describe of shutting down for about 10 minutes after trying to push onto a plane. I replaced the power pack, then the stator was bad, then a bunch of other smaller things and the problem still wouldn't go away. Ended up completely rebuilding the carbs (I know, sounds like a totally unrealted solution but the entire electrical and fuel systems checked out fine). The problem is now gone but in the end I put a lot more $$ into fixing the problem than the engine was really worth. Of course it wasn't one huge bill but the solution was only another couple hundred $$ away at any given time. If I had a crystal ball to see the big picture of what was coming I would now have 2 year old motor on my transom! My advice is to be careful about throwing good $$ after bad as you chase gremlins around on this motor. Good luck!
towboater posted 05-03-2007 06:03 PM ET (US)     Profile for towboater  Send Email to towboater     
Make sure your fuel bulb is is good shape. Replace with alcohol resistant.

OK, electrical aside,
Your problem occurs whenever you increase throttle to dump more gas into the cyls.
Id bet your LOWER carb bowl is full of junk.
Vibration & gravity draws sediment & water DOWN and causes fuel restrictions in the lower carb as you increase RPMs, this alerts the electrical end of issues as Jim explained...when the lower carb isnt dumping equal amounts of gas into the cyl as the other carbs, the engine senses all this and shuts down.
10 minutes later the carb bowl settles or sensors reset...the engine starts and the whole process starts all over.

I know late model Merc 2 stroke lower bowls are very hard to get to, but, not impossible. If anything, I would hire a trusted pro to clean the bowls and then fine tune the carbs so they are all working equally even if you have to wait for his TLC.

Decarb wouldnt hurt.

I have Pro Outboard mechanic Pal that recently said he could simply decarb a lot of the engines he works on and then tell the customer he gave the engine a tune up.
No, he would never do that, it is his way of saying decarb can have substantial results.

mk

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