1973 Merc 200 20hp won't stay running

[Coastal Rick]

I got a boat and this motor about 2 months ago. The first time I fired it up in a barrel of water, it ran pretty smooth, the neutral warm up lever (it has controls) worked fine to rev it slightly just to know it worked fine. I let it run for about 15 minutes and it settled into a nice slow rhythm. I tried it in gear fwd and rev, both seemed to work great.

Next I launched it and it seemed to run just great. I was thinking what a super little outboard although it is the only one I've ever owned, being new to boat ownership. So I putted around for about 30-40 minutes from idle to wide open, no troubles. On the way back to the dock, it started to cut out and almost stall, then picked back up in a few seconds, run ok for about 5-10 seconds then power down again, and did this until it died. I got it restarted, and back to dock. If I ran slow, it seemed like it wasn't affected as much. At the dock I realized I had not opened the fuel tank valve and guessed that I was starving the Merc causing the problems :redface:. Could that cause a permanent problem for my outboard?

I launched it a few days later and this time (valve open ), it was hard to start, when I got it going it seemed to run ok but after about a 3-4 minutes it began cutting out like before and died. I could get it to start but it wouldn't idle up with the warm up lever, only run (roughly) about 5-10 sec then die. It did this about 5 times. So I hooked up the electric trolling motor I brought along and took it back to the dock.

Any ideas of where to start to get it going? I looked for a Mercury service manual but didn't have any luck, so I bought a Seloc manual off iboats and should have it in a couple days or so. Thanks.

 

[Coastal Rick]

Re: 1973 Merc 200 20hp won't stay running

Just checking if anyone can offer a hint to help me out. Thanks.

 

[ryandl0]

Re: 1973 Merc 200 20hp won't stay running

could be water in the carb bowl

 

[Coastal Rick]

Re: 1973 Merc 200 20hp won't stay running

Thanks ryan. Seems like it should be a minor thing, but since I'm taking stuff apart I might as well be proactive and hit a few things that probably need attention. My local marine shop has a full carb kit and fuel pump kit on hand so I'm gonna pick them up, as well as a impeller kit, an while I'm at it I'll change out the lower unit lube. I also located a mercury service manual and that will be on it's way. My plan is to have this thing back on track with my own hands.

 

[Downwindtracker2]

Re: 1973 Merc 200 20hp won't stay running

Warm up lever? choke? That's a good idea about doing the neglected maintenace,most of the posts recommend that. I found on my liitle one it would flood out if the choke was on past the first cough.

 

[Coastal Rick]

Re: 1973 Merc 200 20hp won't stay running

Hi downwind, I'll keep that in mind about the choke. I think I was over doing it when I first tried everything out. I have a LOT to learn.

I got the fuel pump kit and the carb kit (which is no longer available) today so I should be in good shape. The parts guy was pretty excited that he found it on a shelf in their shop. So that was a score I guess. I think I'll need to make a stand so I can work in my garage our of the weather and at night, and get to everything easier.

I have a console with controls, so there is the throttle lever, and a second lever used to bring up the rpms when in idle. It is not connected to the choke as far as I can tell. The old owner's manuals I found online say to bring it up to vertical to start, then lower it back down after it gets running.

Anyone know what spark plugs this thing uses? i pulled them and the upper one was wet, the insulator and post were black but not worn. Is it supposed to be that color or shiny metal and brown ceramic?

 

[Coastal Rick]

Re: 1973 Merc 200 20hp won't stay running

After ryan mentioned water in the carb, I suddenly thought why not change out the gas that came with the boat? So I did that, and with new gas and seafoam (at 2oz/gal) added, it fired right up, and hasn't quit yet! What a relief that it wasn't a major repair issue. I've run it twice so far and put about 5gal gas thru it and it seems to be getting smoother each time. I'll still do the lower unit lube, impeller, carb and fuel pump maintenance - I've got all the parts!

As I tinkered around, the dribbling tell-tale was bugging me. So I disconnected the hose off the top of the #1 cylinder, and removed a small stone lodged in the plastic elbow that exits the cowling. Next time I ran it, it squirted like a champ!

At lower speeds, there is still some adjusting needed. It runs slightly "off" - a little rough with a vibration, then smooths out, then back and forth like that. When I get about 50%-100% throttle, it runs completely smooth. Any suggestions on that?