1989 Merc Black Max--randomly stalls

clove · May 30, 2005

Over the past several weeks I have been trying to find the cause of the random stalling of my 1989 Black Max 135. During this time I have replaced my fuel pump(which was badly needed), and checked for exhaust leaks. Prior to this I had changed the fuel filter and spark plugs. Anyway, over the past several weeks I have been charting the random stalls and have noticed that they appear to happen more frequently during warmer weather. This also brings on a new sympton of a loss of power which brings the boat out of the hole rather sluggishly then all of a sudden all power seems to appear. At this point I am assuming that my problems are spark related(in some manner) but not sure where to look. Can anybody give me some pointers as to what to look for? When it stalls, it appears that I am loosing at least half of the cylinders. Then, if I remove the cover, after about 15 minutes it will start. Until then it will not start at all. Thanks in advance for the help!

KCLOST · May 31, 2005

Re: 1989 Merc Black Max--randomly stalls

GO ahead anc check the spark using a spark gap tester at idle... Report back... This could easily be a switchbox going bad, they can be affected by heat when they begin to go toward the grave... It's common on these motors when they reach this age...

clove · May 31, 2005

Re: 1989 Merc Black Max--randomly stalls

Where do you get such a device? Also, what is the estimated price for the switch box(es)? Is it better to replace both at the same time to avoid future failures?

KCLOST · May 31, 2005

Re: 1989 Merc Black Max--randomly stalls

The spark gap tester can be purchased at any auto parts store. (only around $10)... I guess A timing light will also work but I've never used one for that purpose... The switchbox (if it's the problem) is not cheap.. It will run you about $130 each. And yes, it is best to replace both at the same time if they are the original mercury boxes.. The newer CDI/Rapair boxes do not need to be replaced in pairs if by chance you do have them on your motor, but chances are you don't. I would purchase the boxes from www.seilermarine.com can't beat their prices...

Mike Caspari · May 31, 2005

Re: 1989 Merc Black Max--randomly stalls

140-200 each, depends on the brand. I replaced both for 280 but they were the ones that need to be mated ,from my understanding. Look up my post on 135 on here. Spark tester can be obtained from a local auto parts house, got mine from autozone for 7 bucks. I found that I had a bad switchbox that would only fire #2 cylinder when you got up around 3500 rpm, all the rest fired fine at idle. Keep the old switchboxes, one may still work.

Laotzu · May 31, 2005

Re: 1989 Merc Black Max--randomly stalls

When I had similiar symtoms, it was gunk in one of the carbs( 91' 50hp). What was happening was at idle, ok, but when I applied power, the #1 carb would suck some of the gunk into the jet and starve the #1 cylinder. Before I spent hundreds of $$, I'd disassemble and clean the carbs and blow out the jets with compressed air. Costs about $7 for the cleaner and some time. Jerry

imported_scott_m · Jun 1, 2005

Re: 1989 Merc Black Max--randomly stalls

Not to take you in an entirely different direciton, but I've got the same motor and had the same problem last year. Turned out it was just the fuel line and primer bulb. When it dies, does the primer bulb go soft? Is the vent line clear on your fuel tank.

clove · Jun 2, 2005

Re: 1989 Merc Black Max--randomly stalls

Funny thing you mentioned the fuel bulb/hose. I changed it about a month ago with a new one. Old one was dried and starting to crack. I also change spark plugs and fuel filter. The bulb is not fully soft when it stalls but is definitely not firm. Should it be? I have tried priming it when it stalls but it still does not start. I usually have to wait about 15-20 minutes and the engine fires right up as if nothing happened.

clove · Jun 5, 2005

Re: 1989 Merc Black Max--randomly stalls

ALL: Just wanted to let all those who have suggested things to try that I decided to take the boat/motor to the local marina for diagnosis. Several reasons for doing this but the two biggest are they have the parts/experience and equipment and also if they don't correct it the first time I have ammunition to have it looked at again at little to no cost. I'll advise of the outcome. Thanks again to all who responded!

clove · Jun 10, 2005

Re: 1989 Merc Black Max--randomly stalls

Just got the boat back from marina. Before they tested it they backed it up in the water and noticed that the motor was not peeing very good. So, they dropped the lower unit and noticed that the bead of sealant they put on a month ago when changing the water pump was gone. They added more, installed the L/U and tested it for 40 minutes at all RPMs and could not get it to fail. Could that bead of sealant cause the random stalling I was experiencing? The guys at the marina were not sure, and told me to take the boat and try it again over the weekend. They did not even charge me for their work--just in case they did not catch the problem.

technostingray · Jun 11, 2005

Re: 1989 Merc Black Max--randomly stalls

When I had similiar symtoms, it was gunk in one of the carbs( 91' 50hp). What was happening was at idle, ok, but when I applied power, the #1 carb would suck some of the gunk into the jet and starve the #1 cylinder. Before I spent hundreds of $$, I'd disassemble and clean the carbs and blow out the jets with compressed air. Costs about $7 for the cleaner and some time. Jerry Is it common for outboard motors to have no aircleaners? The jonah I inherited has no aircleaners. It is a 700E inline six as established through much research.

clove · Jun 12, 2005

Re: 1989 Merc Black Max--randomly stalls

This thing is really furstrating me. I took it out on the lake today after getting it back from the marina. First thing--the buzzer alarm constantly beeped from the time I turned the key--started --and ran---it beeped. It would some times cut out and it sounded scratchy then all of a sudden it would come back on--any idea what could be causing this? The little card attached to the inner cover of the motor says a constant beep is a sign of overheating. Can't see how this is valid when the buzzer would come on with the key in the on position and the motor not running. No on to the problem of this thread. Even though the buzzer constantly beeped, I took it out for a short spin, and low and behold, it sluggsihly came out of the hole and was a dog for the whole run(about 8 minutes of it). Given that the marina SAID they could not duplicate it, I decided to come back and do my own checks. Below is what I did along with the results: Compression: Cylinder # Reading 1 118 2 108 3 118 4 115 5 118 6 112 Spark test: Performed while cranking the engine Cylinder # Good spark at distance 1 3/8" Gap and good spark 2 less than 1/4" and marginal 3 less than 1/4" and marginal 4 3/8" Gap and good spark 5 3/8" Gap and good spark 6 3/8" Gap and good spark The spark test appears to be a good clue as to what's happening. I also tested the coils associated with the marginal spark and they appear to be OK. I know that this is a long thread but I really need your help in getting to the bottom of this. Can somebody please help me along with the remainder of the testing necessary to resolve this issue once and for all(and also the new problem of the on-going buzzer)? Thanks in advance!

clove · Jun 13, 2005

Re: 1989 Merc Black Max--randomly stalls

No response yet! I am shocked given all the activity this forum has. I don't need an immediate response but was hoping somebody out there had some suggestions. Thanks to all who have replied earlier.

Laotzu · Jun 13, 2005

Re: 1989 Merc Black Max--randomly stalls

Techno, No air cleaner but they do have a noise abator that fits over the carbs like a filter would. The gunk I referenced was flakes of varnish. The boat had sat for 4 years before I bought it and evidently the varnish came from sitting too long. Strange, but only one of the carbs had varnish. The one closest to the fuel filter. Jerry

Coolmaker · Jun 14, 2005

Re: 1989 Merc Black Max--randomly stalls

Sounds like a switchbox going bad.....swap them and if the weak spark goes to the other side, you will know for sure.

technostingray · Jun 14, 2005

Re: 1989 Merc Black Max--randomly stalls

Hey thanks, laotzu.

KCLOST · Jun 14, 2005

Re: 1989 Merc Black Max--randomly stalls

Do you have those readings (spark) in cylinder # order.... 1,3,5 are on one bank, and 2,4,6 on the other...

clove · Jun 15, 2005

Re: 1989 Merc Black Max--randomly stalls

From a previous message, here are the spark test results: Spark test: Performed while cranking the engine Cylinder # Good spark at distance 1-----------3/8" Gap and good spark 2-----------less than 1/4" and marginal 3-----------less than 1/4" and marginal 4-----------3/8" Gap and good spark 5-----------3/8" Gap and good spark 6-----------3/8" Gap and good spark Thanks for all the help and replies so far. Given my lack of time I have taken the boat back to the Marina for them to follow up on my findings. No word yet but it's only been a day.

technostingray · Jun 15, 2005

Re: 1989 Merc Black Max--randomly stalls

The question from KC was as to how you arrived at the assignment of numbers to the particular cylinder since fireing order is staggered. BOAT

clove · Jun 15, 2005

Re: 1989 Merc Black Max--randomly stalls

My apologies. They are the actual cylinders as labeled on the engine. Sorry for the misundestanding

1989 Merc Black Max--randomly stalls

Seaman

Commander

Seaman

Commander

Cadet

Petty Officer 2nd Class

Petty Officer 2nd Class

Seaman

Seaman

Seaman

Banned

Seaman

Seaman

Petty Officer 2nd Class

Petty Officer 2nd Class

Banned

Commander

Seaman

Banned

Seaman