Instrumentation (and other) issues - Merccruiser 4.3L Gen+

bshellrude

Seaman
Joined
Jul 26, 2004
Messages
66
All,

Just bought a 1999 bayliner capri 1850ls with the MCM 4.3L Gen+ 2BBL Alpha one gen II outdrive...

I have a few problems that I'll list here and hopefully get some input on.

So, 3 problems in order of importance:
1) When shifting into reverse if I give it any gas immediately after shifting, the engine stumbles for a few seconds then stalls. If I shift it in reverse, and wait a few seconds, then give it gas, it seems to be alright. No issues in forward gear... So I've done some reading that there are sometimes issues with the shift interrupter... but my question is - wouldn't the problem rear it's head in both forward and reverse gear? And further to the point, if it wasn't correctly adjusted, wouldn't I be in a situation where immediate throttle or not, it would stall in reverse?

2) My tach wasn't working at all. Previous owner said that it worked fine last year (but maybe didn't register so well at idle). Now after some fumbling around with the connections on the gauge cluster, it seems that upon starting the engine, it immediately goes to 2k (whereas it did nothing before), and slowly reduces to zero as throttle is applied. Previous owner said he had removed the gauge cluster to clean in behind, and might have messed something up, but I've checked wiring diagrams as per service manual and found nothing wrong... Could he have accidentally changed the pole selection dial on the back?? Would that cause these kinds of problems? Any other ideas?

3) Trim Gauge... again previous owner said it worked fine last year. Now it seems like it's pegged at something close to the 11:30 position (not quite straight up, just slightly counter-clockwise of 12). This one doesn't flick/move at all with ignition... I've read that when the trim gauge is pegged "up" that it's more than likely the trim sending switch... However... what exactly is the definition of "pegged"? Is it pegged as in to the upper indicating line on the gauge... or does pegged=12 o'clock position? Is it true that the entire outdrive needs to be removed to replace these switches? and that they have to be done in pairs? I've also noticed that the trim limiter switch is working in the up/out direction (i.e. it cuts power to the trim when it reaches the upper limit before requiring the "trailer" trim switch), but not in the down/in position (i.e. when trimming down, it'll just keep going, so you have to listen for when the tone of the trim changes to know when to let go)... is that normal? Or should it be limiting in the down/in direction as well?
 

jtmarten

Master Chief Petty Officer
Joined
Aug 2, 2004
Messages
825
Re: Instrumentation (and other) issues - Merccruiser 4.3L Gen+

#1 - lower shift cable.

#2 - try switching between 4-6-8 cyl repeatedly. Sometimes the switch gets dirty. If the tach has selections for # of poles intead of cyl, its made for outboards.

#3 - you could try adjusting the trim sender and see if the gauge responds.
Sometimes you can replace them without removing the drive. Just have to be very carefull when splicing the wires, making sure the splice is water-tight.
That's normal operation for a trim switch, there isn't a limit switch for trimming down. You'll either have to listen for it, or watch the trim gauge or voltage gauge.
 

bshellrude

Seaman
Joined
Jul 26, 2004
Messages
66
Re: Instrumentation (and other) issues - Merccruiser 4.3L Gen+

Thanks jtmarten!!

Will try #2 and 3 when I get home.

As for #1... what exactly do you mean by lower shift cable? As in, it's out of adjustment? Can you explain why that would cause the problems I'm seeing? And why only in reverse? It shifts into gear just fine in both sitations, just when I give it gas immediately, it stumbles and dies...
 

bshellrude

Seaman
Joined
Jul 26, 2004
Messages
66
Re: Instrumentation (and other) issues - Merccruiser 4.3L Gen+

Or should I just do a complete shift cable adjustment procedure and see if it cures it?
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,088
Re: Instrumentation (and other) issues - Merccruiser 4.3L Gen+

As for #1... what exactly do you mean by lower shift cable? As in, it's out of adjustment? Can you explain why that would cause the problems I'm seeing? And why only in reverse? It shifts into gear just fine in both sitations, just when I give it gas immediately, it stumbles and dies...

Ayuh,... As the lower shift cable wears Out,....
You're describing the Early Symptoms...
It's past Adjustment,+ headed for Replacement...
Do the Bellows while your there, if they haven't been replaced in the last 5 years or so,...
They're about Done too...
 

bshellrude

Seaman
Joined
Jul 26, 2004
Messages
66
Re: Instrumentation (and other) issues - Merccruiser 4.3L Gen+

oh YAY!!! hehe... not!!!

So... just doing dome really quick searches and scanning some posts regarding the replacement of the lower cable, it seems this is a pretty daunting task??

Can anyone tell me, how tough this is to do?

I'm a pretty accomplished backyard wrencher (i.e. fully rebuilt trucks, transfer cases, engines, etc...)...

How long could one realistically live with this condition? What are the risks? (other than the obvious stranded in the middle of a lake)
 

bshellrude

Seaman
Joined
Jul 26, 2004
Messages
66
Re: Instrumentation (and other) issues - Merccruiser 4.3L Gen+

Also, so let me see if I understand. That because the drive shift cable is worn (i.e. streched/stiff/sticky/etc...), that when I'm putting it into reverse and giving it throttle, it's creating enough resistance that it's inadvertently actuating the Shift Interrupt, thus causing the engine to stumble and stall?

However, when doing it same in forward, the issue does not present itself on account of the force on the cable being reversed?
 
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