1998 50HP Mercury four stroke starting issue

[hubbardsm]

I purchased a boat this summer that has a 1998 mercury 50HP four stroke. The block is a Yamaha and all the rest is Mercury. The motor started up and ran fine when the owner ran it for me. I have been starting it every 3 weeks so that it doesn't sit long and the carburetors get fouled up. The first thing I do is squeeze the primer bulb till it is hard. It's normal routine is for the motor to turn over on the first attempt as long as I'm turning the key (I'm also pushing in to choke it, but I don't think the choke works). However, it doesn't start. When I then turn the key off and then turn it again to restart the motor, the starter gear engages the flywheel, but only turns it about 1/3 turn and stops. It does this several times, and eventually, the starter will just click and not turn the flywheel. I then let it sit for about 1 hour and then when I turn the key, the starter works and the engine fires up. Initially it idles a little rough like it is not getting enough gas, or too much. If I push the throttle forward to give it some gas, it stalls out. It starts right back up though usually. So I have to let it idle slowly for awhile and after about 2-3 minutes of this I can give it some gas and it really seems to run smooth, although idle is a little fast - like 1800 to 2000 rpm. I think manual says it should idle around 600-700. I then can shut the motor off and it will start up immediately as many times as I want and run smooth. The battery is new and fully charged and I've polished all the battery connections and the connections going to the starter. When I bought the boat, it had been sitting for awhile so I put about 6 gallons of fresh gas in it and added some stabil. I think it only had about 1 gallon of old gas in the tank.

Another issue is I also don't hear any click when I push in the key to choke it, so I'm wondering if the choke is even working.

Any help would be greatly appreciated with the starter issue, choke and initial rough idle. I don't want to take it to a dealer yet, because I can't afford $100 per hour labor, and figure it shouldn't be that big of a problem, since it runs fine eventually. I did buy a service manual, but I'm not very good with mechanical stuff.

 

[giericd]

Re: 1998 50HP Mercury four stroke starting issue

i have a 60hp merc and it did a lot of the same things. i would be concerned with a merc with a lot of yam parts or a yam with a lot of merc parts on it! there is no need to ever do that other than some back woods hill billy trying to take 2 broken engines to make 1 that works with out spending a penny! you realize you will probably never be able to take it any where for service except for Billy Bob that created that Frakenstine. First place i would start is clean the carbs older mercs are known for carb issues and i'm sure it was sitting for a while so go through the carbs. I got a dirtbike the other day that would start on the first kick run for a few sec and die. the 4 wheeler did the same thing. took the carbs off and it looked like wet cornflakes in the carb bowl! Paid $125 for both bikes and had them runnung great by the end of the day best deal i ever got and that was what a little cleaning of the carb will do! unitll you clean the carbs I wouldn't chase any other ghosts. if you still have issues after cleaning the carbs post a nother post and you will be guided from there but that needs to be priority #1. get back to us with the results

 

[Faztbullet]

Re: 1998 50HP Mercury four stroke starting issue

Uh.... Yamaha made the Merc 4 strokes for several years, this aint a mix and match motor.

 

[hubbardsm]

Re: 1998 50HP Mercury four stroke starting issue

Actually, I verified with the Mercury dealer that the engine is Yamaha, but the electrical, carburetors, lower unit and everything else are Mercury parts.

Thanks for the reply.

 

[Silvertip]

Re: 1998 50HP Mercury four stroke starting issue

The first step is to make sure you have a good battery and that the charging system is working. clicking of the starter solenoid and failure to spin the engine is symptomatic of a weak/discharged/bad battery or loose or corroded battery cables. Looking at the cables is not a valid check. Remove them, thoroughly clean the connections, inspect for corrosion where the insulation meets the terminals. If corrosion is present, replace the cable(s) or cut the ends off and install new ones. Remember -- battery cables have two ends. Both ends need to be squeaky clean and tight for proper current flow. If the battery is suspect, have it load tested at any auto store. To check the choke/primer operation, remove the engine cover, turn the key to RUN and then have someone push in on the key while you look at the engine. If there is no click - fix the problem. Chances are it is NOT the ignition switch which is typically the first thing you might be tempted to jump on.

 

[Faztbullet]

Re: 1998 50HP Mercury four stroke starting issue

After re reading you original post it sounds like the choke thermal valve or unloader is sticking not allowing choke plates to pull closed. Remember this is a 4 stroke and choke system works similar to a early automobile.....

 

[hubbardsm]

Re: 1998 50HP Mercury four stroke starting issue

Thanks for your tips Silvertip and Fatzbullet. I did file/sand the connections at the battery and starter last month and wherever I could find a wire going to them. The battery is new and it is fully charged per my charger. As you suggest, It does sound like a wire/connection problem. It will turn over the first time for as many seconds as I turn the key, and it is the subsequent attempts where the starter just doesn't want to turn over much. I will check the wires where they meet the connections.

I also read in the manual last night that if your idle is above 1500 rpm, (mine is 1800-2000) that it makes the engine hard to start when it is cold, which is what happens to me. Once I get the engine running, I can shut it off and restart it as many times as I want without a problem. The manual said to adjust the fast idle screw so I will try that also. I will also check the choke as you both mentioned.

Thanks again for the responses.