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1984 Mercury Outboard 75HP needs help, please.

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Barefiel76

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I am restoring a 1984 4 Winns Catalina 150. 1984 Mercury Outboard 75HP sat for a long time before I recieved it. I installed a new impellar and the motor started in the drive with a hose. No problems there. Finally got to go for a ride last weekend. Boat started sounded good, it ran for about 7-8 mins without any problems. I put it in neutral, started to accelerate and the motor bogged down. It stalled after about 40 seconds and would not restart.

At home I installed 4 new spark plugs sprayed a little starting fluid and checked fuel supply. Fuel is good from gas tank to fuel filter. Plug has a strong spark. Plug appears damp with fuel when I pulled it after trying to start. Engine acts like it wants to start but just will not completely catch. I would appreciate any help.
 
It might simply be flooded. Try this: Pull (and clean) the plugs, then spin it over for 10 seconds with the plugs out. Ground the plugs to the block as you do this. Then reinstall the plugs, hit it with ether, and see what happens. Be sure to give it lots of idle up--they like that.

Jeff
 
fastjeff said:
It might simply be flooded. Try this: Pull (and clean) the plugs, then spin it over for 10 seconds with the plugs out. Ground the plugs to the block as you do this. Then reinstall the plugs, hit it with ether, and see what happens. Be sure to give it lots of idle up--they like that.

Jeff
Click to expand...

Thank you for the idea. I tried that and still won't turn over. It's almost as if there is a clog somewhere in the fuel line. I checked the fuel filter and it is clean. I am waiting on a manual from the library to come in so that I can try to track this down. I would appreciate any more ideas.
 
Pull the plugs and squirt/spray some Seafoam into the holes, reinstall the plugs and see if it will fire. If it does then fuel is the place to start. Rebuild the 1984 fuel pump, replace fuel lines if necessary, rebuild the carbs or drain them and fill them w/Seafoam using the primer bulb/hose and let them sit 48 hours so the varnish will dissolve. When you fire it up it will smoke alot until it get a gas/oil mix.
 
Either it's getting gas or it's not. If you think the problem is in the fuel line, remove the hose going to the carbs at the fuel pump and see what happens when you pump the bulb.

Jeff
 
fastjeff said:
Either it's getting gas or it's not. If you think the problem is in the fuel line, remove the hose going to the carbs at the fuel pump and see what happens when you pump the bulb.

Jeff
Click to expand...

I can get it running with the engine throttled up a little bit and the motor in neutral. The gas I'm using is brand new. But you are right that I have no idea if there is water somewhere in the carb. I am planning on getting a rebuild kit and doing that this weekend.

Does that sound like the next logical step? It appears to have a small drip from the bowl on the botto
Ok of the carb but I can not tell where it is coming from? I've been part of a boating family for 25 yrs but this is the first time it's been my issue to resolve. I am grateful for the help.
 
The carbs are 28 yrs. old...give them a long soak to dissolve the hardened varnish buildup in the idle circuits. After complete disassembly I just drop the carb metal parts into a metal coffee can w/a lid and add lacquer thinner to cover it. Store it outdoors in the shade for 24-48 hrs. and then blow out all of the passages w/compressed air.
 
Take a 1/2 " wrench and remove the brass plug in the bottom front of the carb, then pump some gas through it. Then put it back in and do the same thing with the top carb. THat flushes the crud out.

You might get lucky.

Jeff
 
I took the 1/2" screws out and the metal plate covering the the two carbs. I sprayed carb cleaner inside every possible hole. I did this a couple of times. I cleaned some crude out with an air compressor and pumped fuel through the carbs. There was a pretty good fuel flow through both of the holes where the screws came from. I put things back together and tried to start the motor. When the motor is cold it is a really hard start. After disengaging the prop and pushing the throttle forward I was able to get the motor started. It stays running around 1,500-2,000 rpms. Once it warmed up for a few minutes I pushed the throttle back to neutral and it stays running. I noticed that it seems like a lot of fuel in the water discharge. I know there should be some, but could this be connected to the starting problem?

Also, I had to replace all the interior. In the process I needed to remove the throttle. Could the throttle cable being in a a different spot or moved cause the starting issues?

Thanks, Brandon
 
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