Engine quits off start w/ full throttle-Merc Black Max 150

[heritagesoftail]

Just bought 1986 Glastron Black Max xr2 150 hp 6 cylider, serial number A181697. When trying to get a wakeboarder out of water the engine will try to go and you can begin to get someone out of water but then it quits. <br />If you let off the throttle a bit and on again it helps for a mere extra few seconds. It sometimes will also do this with out a load too if you want to pin it off the start. What is wrong?<br />The spark plugs that were in - NGK BUHW, a local marine store said they were wrong, said to put in NGK BUH8 - they seemed to make it worse. What is right? Sorry for long question. I am green at this. Thank you for help.

 

[LubeDude]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

I have an 87 Merc 150 that does the same thing, however, if you hammer it it will take right off, I have done everything you can imagine (from fuel pump to cleaning carbs), but replace the reeds which I have but have not taken the time to do. I have no spitting back through the carbs though, so Im not convinced that the reeds are the problem either. If you push the choke untill it starts to stumble, and then give it throtle, will it take off then. Or try to push the choke at the same time you push the throtle forward, you will need someone to hold the wheel while you try this. If this works, you may get by with a carb rebuild, but it didnt help mine. Over the last year I have learned how to live with mine. I will tell you this, it will not heal itself!

 

[heritagesoftail]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

Thank you LubeDude. I am not sure if I can reply like this or have to go to a differnt topic. I have tried to hammer it down too, and it still just dies out. It is a little disheartening to hear that you have tried so many options and nothing helps. I need it fixed. Could it have anything to do with the electrical?

 

[DOCD9501]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

I had a xr 4 do the same thing. It could be a plugged carb port or possible even a stator. The stator has 2 side one low rpm one high. How does it run once it gets on plane? Ya might check it just to make sure. These motors also have a spark advance module that has been known to act up. Check it to. Good luck!

 

[LubeDude]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

Im thinking that it may be some kind of an electrical problem also, if I give it just a little throtle off idle, it will seem to come and go from running real smooth to rough again like every ten seconds or so.

 

[DOCD9501]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

imm no expert but ive been thought a xr 4 with fine tooth comb and thats what it seems like to me. Sometimes when switch boxes go bad they can cause intermediate spark which of course is bad. Killed a powerhead of mine (predetonation). Or they can cause misses at certain rpm. And if the spark gets week it will show more pulling a load.

 

[dakk1]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

Dawn W and others..<br /><br />I have the 1985 Merc Black Max 150 XR2. It also does just exactly as you describe. I have been completely through the fuel system, new hoses, rebuilt carbs, rebuilt fuel pump, run from a remote tank etc. This year, I began to look at the ignition system. I have tested (with DVA where called for) the stator, trigger, coils, rectifier, idle stabilizer and finally found that I was dropping #4 cylinder occassionally. I believed that to be caused by a bad SCR in one switchbox. So, I replaced both switchboxes yesterday. This morning I cranked it on the muffs, seemed to idle a little better than usual, then headed off to the lake for a load test. First throttle up she stumbled. Second throttle up she came up and ran beautifully. Smooth and fast. Eased off to take a look at everything and couldn't get on plane again. Frustrating. The ignition components left for me to replace, in the order of likelihood of failure, are the stator, trigger, coils, and the flywheel. I have read here that Merc stators are failure prone. A couple easy things you can check are the idle stabilizer/spark advance module (as docd9501 said) and the rectifier. Just temporarily disconnect them. Idle stablilizer is the rectangular box behind the flywheel. One wire goes to the black/white terminal and the other goes to the red/white on the outer switchbox. Put all other wires back like they were. The rectifier is square shaped match book sized above the switchboxes. Has one red wire and two yellow wires (from the stator) and probably a tan wire with one of the yellow ones. Tan wire goes to your tach. Disconnect the yellow wires and tape all these off. Tach wont work while these are disconnected. Honestly, these are probably not your problem. I doubt if your that lucky! LOL. But you have to start eliminating stuff and these are easy to eliminate. Your gonna' need a Merc manual. I'm about to order a stator (there goes another $165+ bucks.) LOL. Sorry for the long post. Therapy for me. LOL. Hope it helps some.<br /><br />Dave..

 

[LubeDude]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

I replaced the Stator on mine, but when it failed, I new it, it ran terrable but would get on plane. Ive replaced the rectifier also, but I did that because it was charging intermitently. Seems the only thing I havnt checked or changed is the Spark advance stablizer. This engine runs so good at all throttle positions, I dont think im dropping a cylider.<br /><br />The thing that ticks me off the most is that I could have made the owner when I bought it fix it before I bought it, but in my infinate wisdom figured that it was just bad gas. Even the good guys can screw up. Or, Sometimes we are not as smart as we think we are. Or, well, you get the Idea.

 

[heritagesoftail]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

docd9501 - it runs fine once on plane. Sometimes it will not make it to plane, 10 minutes later I can get up to full speed in no time (with a little hesitation, but it does get there)<br />Thank you everyone for your info. Did compression test for cylinders, all 6 are ok. Next moving to fuel pump. If that does not work I will try next for the spark advance module. Again thanks for all the ideas, I can't wait to get back on the water.

 

[KCLOST]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

Sorry for the interuption... But is there a spark advance Module on all V6 Mercs?

 

[dakk1]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

KC<br /><br />My 1985 Merc 150 V6 has only the idle stabilizer, which I have disconnected while I'm testing all this stuff. Someone on this forum said Merc's are like Ramblers, you never knew what you had 'till you raised the hood...LOL.<br /><br />Dave..

 

[heritagesoftail]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

To dakk1. I am not the fixer on the boat, my husband is. He is a bit more familiar with inboards, I just do the writting and try to help as much as can. Anyway, thanks for all the possibilities. Unfortunately we have to resort to a mechanic. They have said that it might be the Stator now, and I was wondering if you had replaced yours and how it was working? (I just don't want to get screwed around by a marine shop). If I can get the boat running good enough I will sell it, only had it for 3 weeks but it causing too much trouble already hopefully it goes quick. sorry for the extra writing, just frustrated that buy something and 2 days later it does not work.

 

[dakk1]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

Dawn W<br /><br />I am installing my stator today. Hopefully, I can get to the lake tomorrow to test mine. Life keeps getting in the way! LOL. There is a good chance the stator is your problem. It seems to be a common failure on outboards in general. Might be all it needs and you'll be set. I hope so. Hang in there..<br /><br />Dave..

 

[AndyL]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

I thought there was a resistance check that could be done on the stator that should point to it being or not being the source of the problem. Sounds like a pretty expensive fault diagnosis tool if you replace it and the fault still exists.

 

[heritagesoftail]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

Thanks again dakk 1, hopefully all goes well for you. The mechanics also said I might need bearings too. I hope I am not being took. AndyL, thanks, I will see if the mech's checked that or not, if possible. They said stator is about 200 and labor, so if it doesn't fix problem can I hold them accountable?

 

[wilde1j]

Re: Engine quits off start w/ full throttle-Merc Black Max 150

Ask them to guarantee the repair with the correct part(s), not just start throwing parts at ther motor until it runs right. The ignition parts on most outboards are among the most expensive parts of the motor. Mechanics that are any good should know how the properly diagnose, before taking wrench in hand! For any repairs I have dealers do, unless I'm absolutely certain, I do not tell them what to replace, just the symptoms and anything I've already done. Any dealer who won't work on this basis, you don't want messing with your motor.