4.3 Mercruiser - Stalled - Will not start

M

Mulligan18

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Jun 1, 2016
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Good morning friends.

I have a 1994 Merc 4.3LX. Had it out last night. It started and putted over to the gas dock just fine. Filled with gas and restarted just fine. Proceeded out into the bay maybe 200 yards at a slow speed - maybe 1,500 RPM's. I increased the speed a little and then maybe to half throttle in order to come up to a plane. Engine stalled instantly - like the key was turned off. Brought the throttle down to idle position. Restarted just fine. Headed back to the dock at near idle - running just fine. Tested out acceleration - stalled. Restarted and idled back to the dock. When docked I throttled up in neutral - stalled. Restarted - throttle up, stalled. Attempt to restart - nothing. No ignition - no click - silent.

Prior problems and fixes include - two new batteries, new fuel pump, new cap and rotor, new plugs, new anti siphon valve at the fuel tank, Cleaned the main ground and many other electrical connections, rebuilt carb installed and then replaced back with original as the rebuilt carb seemed defective. History of backfiring through the carb corrected. Had been running fine for a few short outings this year. Some problems with stalling when shifting between forward, neutral and reverse especially when docking in a breeze. This problem has been annoying but not terrible. I had visually inspected the shift interrupter switch and viewed operation with engine off. All seems fine. Throttle level seems to move freely with no sticking or binding. I had been planning to figure out how to install a new interrupter of the new design.

I have not gone through any type of diagnosis. Seems to be electrical. Any thoughts? Could the interrupter switch be causing this?

Thank you,
 
Bondo

Bondo

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Some problems with stalling when shifting between forward, neutral and reverse especially when docking in a breeze. This problem has been annoying but not terrible. I had visually inspected the shift interrupter switch and viewed operation with engine off. All seems fine. Throttle level seems to move freely with no sticking or binding. I had been planning to figure out how to install a new interrupter of the new design.
Click to expand...

Ayuh,..... My guess is yer lower shaft cable is failin', causin' the shift switch to actuate,....
 
NHGuy

NHGuy

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Also check for 14. 3 volts when running, 12.6 when not.
 
M

Mulligan18

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Jun 1, 2016
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Any idea of the cost to replace the lower shift cable and interrupter switch? Anything else that should be done with such a job? Why no start with the boat at the dock in neutral?
 
thumpar

thumpar

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Jun 21, 2007
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You don't need the switch it is obviously working. All you need is the cable. They are not hard to replace. You just need to make sure it is adjusted when installed.
 
M

Mulligan18

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Thumper. I am having trouble understanding a portion of the problem. If it may be the cable then why would it not start (not turning over at all) while in neutral when the cable seemingly would not be in play?
 
thumpar

thumpar

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It could be a combo of problems. The neutral safety switch may not be worked also. The neutral safety switch will not cause the stalling issue though just starting.
 
Bt Doctur

Bt Doctur

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Aug 29, 2004
Messages
19,349
Couple of quick tests. locate the slave solenoid and jump the 2 large lugs. motor should spin Y,N
Do the gauges come alive with the key in the "on" position Y,N
 
M

Mulligan18

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BT Doctur. Thank you for the suggestions. I will be out of town for the weekend. I will check on this Monday night.
 
M

Mulligan18

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Cutting the grass then going out to the boat tonight for a look.

BT Doctor - Where do I find this Slave Solenoid? (I will check on the gauges as well)

Fishermark - Regarding my vague reference to my observations. I worked the throttle with my foot while looking at the shift linkage (with the boat off, of course). I observed the linkage move as would seem to be normal.. I saw the switch work. Everything in and around the area appears fine. Wires are clearly visible and undamaged.

Thank you,
Mulligan 18
 
Bondo

Bondo

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Regarding my vague reference to my observations. I worked the throttle with my foot while looking at the shift linkage (with the boat off, of course). I observed the linkage move as would seem to be normal.. I saw the switch work. Everything in and around the area appears fine. Wires are clearly visible and undamaged.
Click to expand...

Ayuh,..... With the motor Not runnin', 'n the boat in the water,....

The switch should Not move, at All,.....

That's a sign of a draggin' failin' lower shift cable,.....
 
M

Mulligan18

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Jun 1, 2016
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Lawn tractor quit. (primal screams). Had to push. Boat tomorrow. Allow me to clarify on the switch. I saw the mechanism push the little button on the side of the switch as I was moving the throttle lever. I am probably not describing it well. It's been about a week since I did that so I am not able to visualize as clear as I should. Fixing the dishwasher tonight (yes, that too) and then out to the boat tomorrow to get a better look at things and to find the slave solenoid. Me thinks that in the end it will be the lower shift cable (But I am still confused at how that would create a no-start sitting at the dock in neutral). I don't think I will do that. I will get my daughter to tow the boat to a shop with her truck and get the credit card ready. I seem to recall that the lower shift cable involved a removal of the outdrive. Anything I should be looking to replace as well when that is apart?
 
M

Mulligan18

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Jun 1, 2016
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Good evening gentlemen. I just returned from my boat (better described as a float). Good news and bad news, I guess. Here is what I did and found.
1. Key to the ON position. Gauges come to life. Repeat - same.
2. Continue to ignition position and the engine starts.
3. Increased RPM's just to a fast idle for a moment or two. No problem.
4. Increased to 2,000 RPM or more, no problem and reduced to about 900 RPM.
5. While idling, I reached in and touched the black wire originating from the bottom of the shift interrupter - engine stopped immediately.
6. Go back to the key - turn off- turn to ON - Gauges dead.
7. Continue to ignition position - no start.
8. Fiddle with the black wire. Looks like a solid connection. Try ignition - Still no start.
9. Locate the slave solenoid.
10. Key to ON position. Jumped Slave - engine starts. Remove jump - engine dies.

So, a slave solenoid? Maybe something else?

All comments, suggestions, information and questions are welcome and greatly appreciated.

Thank you,
Mulligan18
 
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