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Throttle problem on 1984 150hp Merccan anybody please help

steve

Contributing Member
" (Sorry if some of this s

" (Sorry if some of this seems "weird"...instead of re-typing the whole thing, I just copied and pasted it from another site that I go on)


I took the "new" boat out today, and it's still having the same problem it did a few years ago back in Jersey. It's a 1984 Merc 150hp Blackmax. I'll start from the beginning, but try to keep it short...lol.

A few years ago, we were fishing a 2 day tourney back in Jersey. The engine was running fine. On the 2nd day we come back in for gas. As we head out the inlet, we go to give here some throttle, and she won't go over 2000 RPMs. Check things out, and couldn't find anything wrong. She's not overheating, so we just get the RPMs down, and limped around the rest of the day.

We took it the mechanic, and he replaced the Idle control motor (or module, or something like that...I forget). We take it out, and it still has the same problem. The mechanic did a few more things, but still had the same problem.

After that, the boat wasn't used anymore. It sat in the storage yard for 2 years. During that time, we replaced all the internal and external fuel lines (someone said that the lines could be deteriorating inside, and causing a shortage of fuel when the throttle was applied). Also, my father replaced the spark plugs, and rebuilt the fuel and water pumps, and replaced the fitting on the end of the gas line, where it connects to the motor.

When I ran it today and it had the same problem, I hooked it up to a small tank that I brought along, just to rule out the problem being with the tank in the boat. On the small tank, it still had the problem, so that isolates the problem to the engine. It runs fine under 2000 RPMs....no problems at all.

When you try to give it throttle, it doesn't get above 2000 RPMs. It seems that she wants to go, and the power is there, but it sputters and won't go.

I'm no mechanic, and don't have alot of experience with engines, but I'm thinking that there's 2 problems that it could be.
#1) the Carbs (3 in total). Maybe the high speed jets are blocked, but it seems unlikely, because what are the possibility that all 3 of them are clogged all at once? If just one was clogged, would I experience this much of a problem?
or
#2) The engine timing. Maybe when I'm trying to give it throttle, the spark just isn't there, and she's sputtering. This seems like it could very well be the problem, and makes sense.

Anybody on here think it could be one of these problems, or is there something else you think it might be? I don't have the $ to take it to a mechanic right now, so I'm hoping that it's something I can fix myself. To me it doesn't seem too serious of a problem. I just brought the boat down from NJ, and I'm itching to get out there fishing, so I really want to get this fixed soon.

Thanks for any help or advice you can give me

(P.S. A few people have told me that they suspect it could be either the Stator, or the Power Pack [does a 1984 engine have a powerpack?]. I just want to get a few more opinions, and hopefully some advice how I can check it out myself.) "
 
Do a compression test ( p

Do a compression test ( post results).Check that you have spark that will jump a gap of at least 7/16" on EACH cylinder. When you are going "full" throttle shine flashlight into each carburetor bore and compare the amount of fuel coming up the main jet.
 
" Also check the ignition cont

" Also check the ignition control boxes. The motor has two. They are located on the right side when looking from the back of the motor. If one has gone bad, the motor will idle, but will be down on power and not accelerate. Check your spark on each cylinder. I bet one side is not firing.
Try this.
Hope it helps
Good luck and have fun on the water "
 
" After sitting up for two yea

" After sitting up for two years, I would seriously consider cleaning out the carbs. "
 
Steve
I agree with everythi


Steve
I agree with everything said above but in my experience over the years it sounds like a classic case of stator failure. Ill give you a bit of a background. Those stators have a set of windings for high speed operation and another set for low speed. The low speed generally operate at 2000 rpm and below. Above 2000rpm the high speed windings take over. It seems like your high speed windings have failed. You can test the stator using a multimeter. If you need specs let me know and ill post them. In adition to that I would follow marci s recommendations to remove and clean the carbs because after 2 years of sitting they will require a clean.
 
" Steve,

I agree with Tonya


" Steve,

I agree with Tonyaus. The stator does behave as he describes, however it can be tough to troubleshoot. If you decide to replace it, the best way to go is a rebuilt unit from Rapair Electronics. You could obtain this from www.seilermarine.com at a reasonable price. These units are far better than the originals, in fact Quicksilver sells many of them as if they are oem parts.

Tony "
 
" Thanks for the replies. I&#3

" Thanks for the replies. I'm going to check out the Stator this weekend. I was told that I can check it with my Ohmmeter. What exactly do I need to cehck for (what readings)?
If it checks out OK, then I'm gonna check out the Carbs. If they also check out OK, then I'm gonna check the powerpack. Is there a way for me to check it myself, or do I need to have a mechanic do it?
Thanks again "
 
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