1999 Merc 3 cylinder problems

[nychris17]

starts fine but when put in gear stumbles/hesitates and wont go top speed. I checked out the plugs after every run and their covered in oil. Thanks.

 

[Flounderhook]

Re: 1999 Merc 3 cylinder problems

Sounds like my problem with my 96 60 hp bigfoot Merc, mine however runs fine for 30 min or so and then will hesitate and sometimes stall and will not run full speed at full throttle,dropping to 400 rpm when it normally runs at 5000.If I shut mine off after this happens it is hard starting.I changed plugs,thermostat, poppet valve, still no help.Has feul stabil. and dry gas in. Mechanics are picking up today I will keep you updated if you would like.

 

[nychris17]

Re: 1999 Merc 3 cylinder problems

Yes that would be very helpful of you<br />Thank You

 

[riverebel]

Re: 1999 Merc 3 cylinder problems

Founderhook.I also have a 96 merc 60 hp bigfoot with identical problem. I would appreciate the info too.Mine is on a 22 ft Fisher Pontoon.It runs about 30 min.& stumbles like it is running out of gas & won't go over 3000 rpm. After it sits awhile,it is ready to go for another 30 min trip. THANKS

 

[sharkcat]

Re: 1999 Merc 3 cylinder problems

Check the coil end of the plug leads I think youll find that #3 is corroded causing the cylinder to drop out. Hope this helps

 

[The Marine Doctor]

Re: 1999 Merc 3 cylinder problems

nychris17<br /><br />Check the compression and spark. Then get back to us.<br /><br />TMD

 

[Flounderhook]

Re: 1999 Merc 3 cylinder problems

Talked to mechanic today he said there is water getting into one cylinder, not sure where it is coming from possibly lower unit??? does this sound right?

 

[nychris17]

Re: 1999 Merc 3 cylinder problems

Compression is 100psi. Could one of the power packs not be working properly or when it gets too hot start to not work properly?

 

[Flounderhook]

Re: 1999 Merc 3 cylinder problems

Stopped by to check my boat and was shown where saltwater was getting in and sitting along the bottom of the engine (under the moter cover) still trying to figure out how it is getting there...???test running on wed will update.

 

[Flounderhook]

Re: 1999 Merc 3 cylinder problems

Saltwater getting in up through shift shaft when the moter is trimmed up, is there a way to keep water out in the first place??