97 Sundancer Port engine no spark?

C

captaindick

New Member
Oct 4, 2019
2
Boat Info
270 Sundancer
Engines
4.3 merc
Hey guys,
Just recently picked up a 97 Sundancer with twin 4.3L mercs. Took the chance on not sea trialing it. (Im a dummy) anyways everything was great for about 30 mins and out of no where the port engine shut down. Tried to restart to no avail so limped it back and took it home.

Issue is there is no spark on port engine but cranks all day long. Odd part was the previous owner said you have to have both keys to ON position and press emergency-start to start the port engine. This is my first twin engine boat, so i didn't think much of it. Plus both engines fired up perfectly when purchased.

I think there are multiple issues. 1. I don't think you should HAVE to press emergency to start port side. Should I even need the starboard side key on? Without emergency pressed the port side does nothing. 2. obviously no spark issue. I have already put a new coil in and cleaned cap, rotor. I have 12v's at the coil but still no spark from it.

Any ideas would be great. Pretty frustrated I can't find this issue.
 
Check the ignition sensor located under the distributor rotor. They are a common failure item that mercruiser has redesigned. If this sensor has failed there will be no spark and the fuel pump will not activate either.
 
I'd move back to your need to supply 12v to the port from the starboard bank.
That smells like a drained/bad battery, and I'd bet that the alternator is kaput on that side.
I have had a similar situation where I wound up running down the port side because all the lights and stereo were on, and the generator had quit without me knowing it. The alternator wasn't working but I didn't know that at the time. Ran that battery so low the engine quit, and I could not restart it.
If you can't get that engine to turn over on just the port battery, then it won't run either once you let go of the emergency override.
 
370Dancer said:
I'd move back to your need to supply 12v to the port from the starboard bank.
That smells like a drained/bad battery, and I'd bet that the alternator is kaput on that side.
I have had a similar situation where I wound up running down the port side because all the lights and stereo were on, and the generator had quit without me knowing it. The alternator wasn't working but I didn't know that at the time. Ran that battery so low the engine quit, and I could not restart it.
If you can't get that engine to turn over on just the port battery, then it won't run either once you let go of the emergency override.
Click to expand...
Yeah I hear yeah. My thinking right now is to get spark then worry about that emergency switch. I think next I’ll be pulling the battery’s and have them tested. Also as for the ignition sensor I tested to see if the coil was giving juice to the distributor and that came up negative as well.
 
Had the same issue with my 97 sun dancer 4.3s, replaced distributor pickup and rotor,problem solved
 
I have a 98 with twin 5.0. I found out that their is fuses in the efi box. Not sure with yours but mine is mounted to the right riser. if you lift that lid you will see 3 fuses. I only know that the last one works the fuel pump. ( found that out after 3 hours of scrathing the old noggin) might not help but worth a look see
 
In this box if ya have it.
20191008_051657.jpg
 
Those are carbureted 4.3's I am guessing? Same as mine.

1. Make sure the battery is good and check the alternator - if it starts with a good battery, just put a volt meter on the battery terminals, should see 13.5 - 14.5v if not the alternator is not working. Engine will run for awhile until it drains the battery.
2. Check all the connections at the batteries and ignition switches. On that boat each engine has it's own battery and ignition switch - all the emergency switch does is combine the batteries so you can start an engine with a dead battery. Nothing sophisticated about it.
3. As others have said, check the ignition sensor - if it is the older style where you can see the wires connected on it, just toss it and get the newer sealed style. The old ones have pretty much a 100% failure rate.
 
'95 370 Sundancer with the same issue on starboard engine. Provided picture of distributor cap is this the older style that you were saying needs to be replaced?
 

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captaindick said:
Hey guys,
Just recently picked up a 97 Sundancer with twin 4.3L mercs. Took the chance on not sea trialing it. (Im a dummy) anyways everything was great for about 30 mins and out of no where the port engine shut down. Tried to restart to no avail so limped it back and took it home.

Issue is there is no spark on port engine but cranks all day long. Odd part was the previous owner said you have to have both keys to ON position and press emergency-start to start the port engine. This is my first twin engine boat, so i didn't think much of it. Plus both engines fired up perfectly when purchased.

I think there are multiple issues. 1. I don't think you should HAVE to press emergency to start port side. Should I even need the starboard side key on? Without emergency pressed the port side does nothing. 2. obviously no spark issue. I have already put a new coil in and cleaned cap, rotor. I have 12v's at the coil but still no spark from it.

Any ideas would be great. Pretty frustrated I can't find this issue.
Click to expand...

No, you should not need both ignition switches on to start the engine.
No, you should not NEED to use the emergency jump button to start the engines.
But then you say the engine "cranks all day"? With or without the emergency switch pressed and with or without both ignitions on?

It is common for the ignition modules to fail, often after they get hot, let it cool down completely or cool it down with some compressed air in a can.
If it restarts, very likely the module.

But first please provide the serial number we can better confirm the configuration and parts. https://public-mercurymarine.sysonline.com
the 97 model 4.3LX is right on the cusp of Carbs or fuel injection.

But as others pointed out don't be chasing ghosts if you have to use the jumper button fix that issue first.
Many ignition systems wont fire properly with low voltage.
 
Have you checked the cannon plug for the engine harness. I had a similar problem and while shaking wires I discover a couple pins in the cannon plug were not making a good connection.
 
As mentioned before starboard engine would not turn over unless using emergency start. When using emergency start engine would not fire and there was no spark from coil. Any ideas on the next step?
 
This is for both @captaindick and @Party_of_5 stop focusing on the no spark and focus on the why you need the jump switch in order to crank the other engine.
The jump switch is wired in such a way that as long as either ignition switch circuit has power it will energize the jumper solenoid.
But if the engine will not crank on its own power something is wrong there.
You need a 12volt test light or a multi-meter.
(I wont use port or starboard since you have opposite side problems)

Check the batteries with the AC battery charger turned off, battery switches off, at the battery terminals is there 12 volt?
Repeat with battery switch on, voltage should not drop, turn on ignition, voltage should not drop.
If at any point the voltage drops the battery is not properly charged.

On the bad engine, battery switch on, when you turn on the ignition switch do the gauges energize and show about the same 12 volt as the battery test above?
If not each ignition switch is powered thru a 10A circuit breaker on the breaker panel, AND that is powered thru a 50A breaker mounted on the engine.
Find the breakers, press to reset, if they "click" they were tripped. If they pop out again something is short circuited.
Check both the terminals on each breaker both terminals should have 12 volt.


upload_2021-4-28_18-9-28.png
 
hughespat57 said:
This is for both @captaindick and @Party_of_5 stop focusing on the no spark and focus on the why you need the jump switch in order to crank the other engine.
The jump switch is wired in such a way that as long as either ignition switch circuit has power it will energize the jumper solenoid.
But if the engine will not crank on its own power something is wrong there.
You need a 12volt test light or a multi-meter.
(I wont use port or starboard since you have opposite side problems)

Check the batteries with the AC battery charger turned off, battery switches off, at the battery terminals is there 12 volt?
Repeat with battery switch on, voltage should not drop, turn on ignition, voltage should not drop.
If at any point the voltage drops the battery is not properly charged.

On the bad engine, battery switch on, when you turn on the ignition switch do the gauges energize and show about the same 12 volt as the battery test above?
If not each ignition switch is powered thru a 10A circuit breaker on the breaker panel, AND that is powered thru a 50A breaker mounted on the engine.
Find the breakers, press to reset, if they "click" they were tripped. If they pop out again something is short circuited.
Check both the terminals on each breaker both terminals should have 12 volt.


View attachment 104044
Click to expand...

Thank you so much. This should help.
 
hughespat57 said:
This is for both @captaindick and @Party_of_5

If at any point the voltage drops the battery is not properly charged.

On the bad engine, battery switch on, when you turn on the ignition switch do the gauges energize and show about the same 12 volt as the battery test above?
If not each ignition switch is powered thru a 10A circuit breaker on the breaker panel, AND that is powered thru a 50A breaker mounted on the engine.
Find the breakers, press to reset, if they "click" they were tripped. If they pop out again something is short circuited.
Check both the terminals on each breaker both terminals should have 12 volt.


View attachment 104044
Click to expand...

So when checking voltage I had a reading of 13.30 on one of the batteries but when ignition switch was turned it dropped to 13.27. Are you considering that any drop or did you mean a more significant drop? Also I do not see a 10A breaker but did check the 50A and it was not tripped.
 
Party_of_5 said:
So when checking voltage I had a reading of 13.30 on one of the batteries but when ignition switch was turned it dropped to 13.27. Are you considering that any drop or did you mean a more significant drop? Also I do not see a 10A breaker but did check the 50A and it was not tripped.
Click to expand...
Thats acceptable as long as it stays above 12+
There is an “ignition” breaker somewhere usually 10 could be a dif size

Did you check for voltage on both sides of the 50A breaker to be sure the breaker is working?

If you cant find the ignition breaker then you will have to work behind the helm panel and check the ignition switch. With battery switch on,
Red/Viloet wire - 12+ hot from the 10Amp breaker all times
Violet wire - "Ignition" 12+ hot in Run position
Red/Yellow - "Start" 12+ hot in when held in Start position

I suspect you will have no power on the Red/Violet. This would be bypassed by the jumper button...
 
Last edited:
I cant find a reasonably clear Schematic for either of your years, here is the basic functional layout.
There are many harness connections between the engine, the helm, the breaker panel and the ignition switches.
Need to find where you lose power and back track from that point to the batteries.


upload_2021-5-2_10-33-5.png
 
Well this is completely baffling me. I was trying to check voltage on the 50A breaker and I went to turn the "bad engine" ignition on. The damn engine fired right of and started running. WTH, that engine never fires right off. Glad it started but I still want to get the issue sorted out.

To check voltage on the 50A breaker is that the two posts directly on the back of the breaker?
 
Correct
Breakers contacts can wear out or get corroded and not make proper connection. So just by presses it or wiggling the wires it may be working now. With the meter on it try flexing the wires and see if it drops.
 
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