1985 Mercury Black Max 150 has problems!

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patesw

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When engine is started cranks up and runs great in neutral, but when go to run the boat it bogs down and does not plane out. I can put it back in neutral rev it up go back to gear and it runs out on plane. I have rebuilt all three carbs, replaced all plugs, primer bulb, replaced all fuel lines and fuel filter. I have not rebuilt the fuel pump. Do I need to rebuild fuel pump and what else could I be missing.
 
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Chris1956

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Re: 1985 Mercury Black Max 150 has problems!

So it planes sometimes? sometimes it bogs down? Could be a symptom of a leaking fuel pump diaghram. Do you see raw fuel in the water?
 
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patesw

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Re: 1985 Mercury Black Max 150 has problems!

Chris1956 said:
So it planes sometimes? sometimes it bogs down? Could be a symptom of a leaking fuel pump diaghram. Do you see raw fuel in the water?
Click to expand...

Now that I recall I have seen a small fuel coloration in the water by the motor. The fuel pump is the only thing I have not rebuilt, that will be the next thing on my list. I will order the gaskets and diaphrams and rebuild the fuel pump. Where can I find the parts. Can I purchase this at a bass pro shops?
 
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Chris1956

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Re: 1985 Mercury Black Max 150 has problems!

Don't know about BassPros. It is a fairly old part. iBoats may have it, as may ebasicpower and some others. A Merc dealer may have it. I would expect you to have the fuel pump shaped like a figure 8, right? If you have the rectangular fuel pump, it is a newer and better design.
 
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patesw

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Re: 1985 Mercury Black Max 150 has problems!

Thanks for the help on this issue, I will pick up the gaskets today and water test Monday. I will let you know the outcome.
 
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patesw

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Re: 1985 Mercury Black Max 150 has problems!

I have the fuel pump rebuilt and it started up with no problem. Tomorrow is the real test, putting it on water. Will let you know the results when I get back from lake tomorrow.
 
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patesw

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Re: 1985 Mercury Black Max 150 has problems!

After taking to the lake for water test still bogging down. I can take it to neutral and rev it up a few times and put back in drive and it will plane out. Bulb is not staying firm very long. Its almost like there is a leak in the fuel line somewhere, but I put a new bulb, gas line and fuel filter on.
 
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James R

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Re: 1985 Mercury Black Max 150 has problems!

I am a little late getting in on this. A simple test is to squeeze the bulb when bogging. If it pics up then either the pump is still no good or a leak in the system. If it does not pick up you could have a needle not seating or sticking open causing flooding.
My first checks are compressions so I know that I am dealing with something other than the mechanical health of the motor.
 
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patesw

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Re: 1985 Mercury Black Max 150 has problems!

There is no way to test this without putting in lake right.
 
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James R

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Re: 1985 Mercury Black Max 150 has problems!

Yes that is the way. Motor must be under load so that it is asking for fuel.
 
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patesw

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Re: 1985 Mercury Black Max 150 has problems!

Sorry taking so long to get back. I work a crazy schedule and don't live close to lake thanks for you assistance and patience.
 
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philward

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Re: 1985 Mercury Black Max 150 has problems!

Ya I just got a boat with the same motor and I can get it up to speed and about 15 seconds later it bogs down and I have to throtle back. It seems likes a fuel issue, flooding or something of the sort. Let me know if you figure anything out and ill do the same if I get it fixed!
 
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MercBlackMax1

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Re: 1985 Mercury Black Max 150 has problems!

philward said:
Ya I just got a boat with the same motor and I can get it up to speed and about 15 seconds later it bogs down and I have to throtle back. It seems likes a fuel issue, flooding or something of the sort. Let me know if you figure anything out and ill do the same if I get it fixed!
Click to expand...

I had a similar issue with my 85 200hp. I did a few things to fix the problem 1 took out the anti siphon valves from the tanks. 2 changed all the fuel lines from tanks to motor they where all rotten and had holes so it was sucking air.3 tanks where full of dissinagrated cork from the fuel indicator so it was clogging up my filter screen so i cleaned the tanks. Now the boat planes out runs great and doesnt bog down anymore.
 
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444

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Re: 1985 Mercury Black Max 150 has problems!

After you rebuilt the carbs, did you do a proper link and sync? If your carbs are not synced together properly with each other and the ignition timing, you will bog like you are. My 175 black max did the same as yours but cleared up after doing a link and sync, replacing the water separator, plugs and fuel filter.
 
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