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Engine cutting out while underway

SMH

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Greetings. First time poster. 2000 Four Winns 180 with 4.3 Mercruiser with TB V. Boat was cutting out while underway late in the Fall, not this Spring and then just started again. Marine mechanic did some tests on ignition and did not find anything offside and it didn't act up (of course) when he went for a ride. Its like someone flicks a light switch - its immediate. Does this sometimes at around 1000 rpm and but mostly on plane. After it dies and I return the throttle to neutral, it fires up immediately and off I go to play the game again - intermittent, no pattern and no warning - next 5 minutes or a day from now. Boat never stalls going into or out of gear BTW - shift is smooth and easy.

Threw a few parts at it - coil for one. Has a new dist cap, battery and ignition switch. Cleaned some contacts and checked for frayed wires and poor contacts but electrical diagnostics are not my wheelhouse and all seemed fine to me.

After reading some posts here, I started to explore the shift interrupter. It does kill the engine if I push it in manually. Recently, after it died while on plane, I checked the position of the V-arm without bringing the throttle back to neutral and it seemed to be hanging a bit on the switch - not in the center of the V. Pic enclosed. Makes sense to me that the button on the switch should always be dead center of that V in the arm (except when its doing its thing). Do these arms bind up or have spring tension that gets weak? Didn't seem bound and spring tension feels fairly strong. I did lubricate the pivot point and worked it a bunch. After that I had my son going through the throttle range while I watched the switch and couldn't replicate the position in the pic - it always returned to neutral. Boat ran without incident for 30 minutes. So maybe licked it, but just feels so random.

I also read that a faculty tach can kill ignition? My tach was funky in the fall and now appears dead. Should I remove tach wire from the coil?

I'm away from the boat at the moment, but appreciate any thoughts people have. I'll be back in it tomorrow and can put some more time on it to see if it happens again.
switch.jpg

Thx, Steve
 
the shift interrupter block should pivot freely...thing is, it should only move when the control level is returned to neutral...next time it dies while underway, inspect it BEFORE returning the lever to neutral...with the engine off, things are outside the design space and may not have moved..

other things to check - ignition switch (given it's likely age) and the engine harness connector...you can usually wiggle the key or rap on the dash to see if its vibration/impact sensitive...you can also wiggle the haress on either side of the connector...
 
Thanks - ignition switch new as of last week. I will check the harness.

The pic is as you suggested - a check/pic after it died, key off and before the throttle was moved back to neutral. It definitely hung up a bit. I assumed even some slight pressure on that switch might bugger something up.

What about wire from tach - remove from coil?
 
Tach wire Grey, remove from coil for now.

If shift interuptor switch is closed when issue occurrs and is what the pic shows when it dies, the cables are out of adjustment. That should only move as Mark says, when pulling out of gear back to neutral. If it is in that position when in gear and apply throttle, good chance cables need proper adjustment.

Also, The large black connector (wire harness) is there a hose clamp on it?
 
Tach wire Grey, remove from coil for now.

If shift interuptor switch is closed when issue occurrs and is what the pic shows when it dies, the cables are out of adjustment. That should only move as Mark says, when pulling out of gear back to neutral. If it is in that position when in gear and apply throttle, good chance cables need proper adjustment.

Also, The large black connector (wire harness) is there a hose clamp on it?
thanks for this - will check on that hose clamps tomorrow.
 
Yes to clamp on the connector.

Boat behaved over last 30 minutes

Huh...after our short run i was about to remove the gray tach wire from coil and just noticed there is only one wire (gray) to the negative terminal. One purple to positive. There is is a lone unconnected black wire with small eyelet in the vicinity. Should there normally be two wires to neg terminal?
 
Depends...if there is a tach, then yes...if an ECU is used then maybe...depends on the ignition system used...

Black wires are typically grounded...I would suggest finding what is on the other end of the black wire before doing anything with the dangling ring connector...
 
Definitely a tach on the boat..is an ECM another name for the ignition module on the riser? Where would I find d an ECM if fitted?
 
Thanks

TB V. Carbed. With one gray wire coming off the neg terminal of my coil, does that mean my coil is grounding through my tach??? Apologies for all the novice questions.
 
I pulled the manual and what I stated earlier doesn't apply directly to the TB-V system. There will be only the gray wire on the negative terminal of the coil.. If you traced that gray wire thru the harnesses, you will find a splice where two additional gray wires are added - one goes to the TB module and generates the spark and the other goes to the tach, thru the instrument harness...so, to isolate the tach on the TB-V's you have to pull the gray wire at the tach.
 
I pulled the manual and what I stated earlier doesn't apply directly to the TB-V system. There will be only the gray wire on the negative terminal of the coil.. If you traced that gray wire thru the harnesses, you will find a splice where two additional gray wires are added - one goes to the TB module and generates the spark and the other goes to the tach, thru the instrument harness...so, to isolate the tach on the TB-V's you have to pull the gray wire at the tach.
That's super helpful - thanks. That will be my next try should it go south again. I have been checking the position of the SI switch relative to the V and it seems to be centering now consistently. 1.5hrs of running and good news thus far.

On the manual you referenced - time to get one! Do you have a reco for a paper version. Seloc? My boat is 2000 but not sure which one as manual seems to transition up to 2000 and from 2001.

Engine serial number is
OM 259266

Great forum, thx
 
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