Outboard MARINER 75 ELPTO wont start

S

ssaf

Cadet
Joined
Aug 8, 2025
Messages
23
I purchased a pontoon about 4 months ago. It has a 1989 Mercruser outboard two stroke 75 horse. It has a "binacle" top mount control with tilt.

Key start is in the dashboard. Kill switch is in the dash too.

Everything worked great until about 2 weeks ago. Try to start. Nothing. I can still tilt the motor so I know I have power. Recharged batteries -- all good. New solenoid and new starter engine. Nothing.

The prop turns so it seems like the engine knows it is in neutral.

I am thinking that some sort of electrical signal is telling the engine not to start. But I have no idea what that is. I have not tested the emergency shutoff switch. Is that the place to start or....
 
M

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,243
Per a previous post that has s/n 0G738574 listed. This is a
MARINER 75 ELPTO
Manufacture Date:03/10/1998

Do you have a voltmeter and know how to use it?
Have you checked the fuse? It's in a holder above the starter solenoid.
 
alldodge

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
43,145
I have a 89 Mercruser (0G738574) with the same issue. I am new to boating too.
The button at the bottom of the shift gearbox does not seem to be doing anything.
Can I bypass this --- put the engine into neutral --- so I can start it?
Click to expand...
As muc mentioned a voltmeter would be best to determine fault

Your saying you want to bypass the neutral safety switch?
 
S

ssaf

Cadet
Joined
Aug 8, 2025
Messages
23
muc said:
Per a previous post that has s/n 0G738574 listed. This is a
MARINER 75 ELPTO
Manufacture Date:03/10/1998

Do you have a voltmeter and know how to use it?
Have you checked the fuse? It's in a holder above the starter solenoid.
Click to expand...
I have a voltmeter and sort of know how to use it. I checked the fuse - it is good.
 
M

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,243
At the starter solenoid. The 2 small posts. Yellow with red tracer wire gets the red meter probe. Black probe goes to the small black wire. Turn key to start and see what the meter says.
 
A

airshot

Vice Admiral
Joined
Jul 22, 2008
Messages
5,736
ssaf said:
I replaced solenoid and starter too.
Click to expand...
Folks are more than happy to help on here, but you need to answer their questions and follow their instructions to the letter, otherwise we are guessing as you are. There are certain tests that will give these folks real answers if you would follow along. In my 60 plus years of boating, do you know how many new parts I gave bought and the new ones were bad or another bad part was causing the problem ?
 
S

ssaf

Cadet
Joined
Aug 8, 2025
Messages
23
muc said:
At the starter solenoid. The 2 small posts. Yellow with red tracer wire gets the red meter probe. Black probe goes to the small black wire. Turn key to start and see what the meter says.
Click to expand...
I am at the boat now. We get nothing on voltmeter when we test those wires. Zilch.
 
M

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,243
Now remove one of the meter leads. Hold one end to the big stud on the solenoid with the red wires and then touch the other end to the small stud with the yellow with red tracer wire going to it. Does the motor now crank?
 
M

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,243
I should have said. If the motor now cranks, that means the problem is on the boat side. If so post some pictures of the front and back of both the ignition switch and the throttle lever.
 
M

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,243
alldodge said:
Pics are not working. Would need to upload pic at another location and link here
Click to expand...
Thanks for the heads up, tried to post one the other day and thought I was doing something wrong.
Maybe the OP can post a description of wire colors for switch and controller.
I should add for OP, be careful when jumping starter solenoid. Engine might start if boat harness is disconnected. Might be best to disconnect the spark plug wires before attempting this.
 
M

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,243
racerone said:
Maybe the " crank in neutral only " switch is bad or needs adjusting.
Click to expand...
Possible, I’d probably check for power and ground at the key switch first. But depending on access, might be easier to bypass start in gear switch.
 
J

Jeff J

Petty Officer 2nd Class
Joined
Jun 23, 2021
Messages
133
I had a 90 about that vintage. It acted similar. The main harness connection was the problem on mine. The contacts were corroded. Disconnecting and reconnecting the harness would make it work for a while. I tried to clean it a couple of times but it needed new contacts on both sides of the plug.
 
S

ssaf

Cadet
Joined
Aug 8, 2025
Messages
23
It cranks. On throttle i have two yellow/red wires. One red, one blue, one green. On key it is three purple, two black/yellow, one yellow/black, three black, one red, one yellow/red.

We tried bypassing the switch by connecting black and red. Get chirping and gauges go off, then back on.
 
S

ssaf

Cadet
Joined
Aug 8, 2025
Messages
23
ssaf said:
It cranks. On throttle i have two yellow/red wires. One red, one blue, one green. On key it is three purple, two black/yellow, one yellow/black, three black, one red, one yellow/red.

We tried bypassing the switch by connecting black and red. Get chirping and gauges go off, then back on.
Click to expand...
Gauges work too when I turn switches on.
 
S

ssaf

Cadet
Joined
Aug 8, 2025
Messages
23
ssaf said:
Gauges work too when I turn switches on.
Click to expand...
The gear shifter can feel really hard to move at times and then it seems easy. Also, the button to push at base of gear box to put in neutral...I took the cover off and the button itself cannot come out but it does not seem to do anything but easily slide back and forth. I'm not sure what that is supposed to do.
 
You must log in or register to reply here.
Top