Merc Starting Problem.....Ideas?

[mskrom]

Hi folks-
I have a problem starting the 'big ' motor on my bass boat, and wonder if any of you can help me diagnose it.

First off, it is a 1991 Merc Black Max XR4 150 HP motor. When you first start it at the boat ramp, you can get it running and move out into the lake fine. It will run great........then you stop to fish. Troll around, fish, trim up when you get shallow, etc. Once you are ready to leave, you position the boat into enough water to safely start and run the big motor....and you engage the ignition and crank. (I don't crank too long- no more than starting a car). No dice. Try again......won't turn over. Repeat appx 4 times, and then it won't even crank at all.......it is as if the battery is totally exhausted, and the engine never even gets close to starting.

Thank goodness I was reasonably close to the ramp and I had fully charged trolling batteries.

I bring the boat home, put my charger on the starting battery. It charges for about 3-5 min., and shows a full charge.???????
(by the way, it is a brand new battery, on its first trip to the lake....showed full charge when I left home).

The same thing happened on the last trip of 2007.

I just don't get it......why would it start fine at the ramp, and then no other time?
The previous owner told me to prime the motor before every start, and it used to work fine that way...until the past two trips to the lake. I've wondered if I was flooding the motor, but why would it work before and not now if that were the case?

Any help would be most appreciated.

 

[gss036]

Re: Merc Starting Problem.....Ideas?

Make sure the battery terminals are clean and tight. Get rid of the finger(T)nuts and put on stainless nuts. Double check your shift to make sure it is nuetral/start position. If it is turning over, then you should be ok there.
After it has warmed up, you should not need to choke it to start. May try the choke to see if that helps. Check to make sure you are getting fuel to the carbs(?), pump up the primer bulb. There is a fuel enrichner behind and to the left of the carbs as you are looking at the carbs, push on the button on top and you should hear it click. That indicates it is working and squirts a little fuel into the carb.. Look at the carbs and make sure gas isn't running into the throats, other wise you are probably flooding the engine.
Do you have a fuel/water seperator filter? When was the last time you changed it or at least drained and checked for water?

 

[bigcathunter]

Re: Merc Starting Problem.....Ideas?

same thing hapeened to me last year, ended up being a bad starter motor.

 

[mskrom]

Re: Merc Starting Problem.....Ideas?

Thanks GSS-

My motor won't do anything if it is not in neutral when starting, so I think I'm OK there. I'll have my battery checked, just to be sure, and will also try your suggestion of not using the choke next time after initial start up.

As far as a fuel/water separator is concerened, I would not even know where to look for one. None of the literature I have for the motor mentions it, so I'm 'assuming' no. As I'd mentioned, for whatever reason, this happened the last trip of 07 and the first of 08....... it has worked normally before that.

Strange.....

I did put Sta-Bil in the fuel before storing for the winter, and it did start up pretty easily at the ramp.

At any rate, thanks for you suggestions, and please let me know if you have additional pointers for me-

Thanks

 

[mskrom]

Re: Merc Starting Problem.....Ideas?

same thing hapeened to me last year, ended up being a bad starter motor.

You know, I'd wondered about that as well. Would a bad starter cause the battery/cranking action to act that way?

 

[mskrom]

Re: Merc Starting Problem.....Ideas?

Another thought-

Based on what I posted about being able to crank the starter a few times and then nothing at all-

what do you folks think would be the likelihood that the starter solenoid is bad? Would that cause the ignition 'mis' behavior that I described?

 

[Chris1956]

Re: Merc Starting Problem.....Ideas?

I had a similar problem. I would get 10 sec good cranking out of a fully charged battery and then it would slow down to very slow cranking in the next 5 sec. It turned out to be a bad battery cable. Halfway up the battery cable to the motor, it had rotted out so that only 2-3 strands of copper were still intact. when these got hot from the amperage of the motor, resistance went up and the starter motor slowed down.

 

[mskrom]

Re: Merc Starting Problem.....Ideas?

I had a similar problem. I would get 10 sec good cranking out of a fully charged battery and then it would slow down to very slow cranking in the next 5 sec. It turned out to be a bad battery cable. Halfway up the battery cable to the motor, it had rotted out so that only 2-3 strands of copper were still intact. when these got hot from the amperage of the motor, resistance went up and the starter motor slowed down.

That's really interesting....thanks!
I'll check on this as well.

 

[yorkserv]

Re: Merc Starting Problem.....Ideas?

I am only assuming that there can be something that is draining the battery while you are in the water and just draining it enough to the point where it will turn over so you are not producing enough starting amps. I had a similar problem and it just ended up being that the power knob on my vhf was not shutting power off and while i left the boat in the water with the battery switch on I would slowly drain the battery while i played the stereo. Once I replaced the vhf I never ran into that again. Check all electrical connections tied into the batter and see if maybe you can disconnect all accessories and see if problem persist

Good luck

 

[hkeiner]

Re: Merc Starting Problem.....Ideas?

The below linked thread has a starter troubleshooting guide attached. You may find it helpful. With the help of a multi-meter, you may be able to either difinitively confirm or exclude some possible causes of your problem.


http://forums.iboats.com/showthread.php?t=224094&highlight=starter