496 missing

[Tski17]

While running yesterday at about 3000 rpm, my engine started missing... sounded like a cylinder wasnt firing sort of... The tach bogged down a few hundred rpm also.... I slowed down to idle and it seemed to be ok. After powering back up, it did the same thing. When I got back to the dock I tried flushing it and at idle the engine would shut down, but with a little gas (about 1000 rpm) it seemed to run ok and I was able to flush it out wtih no problem.... I thought it may need new wires, or an ignition coil. Any thoughts? Thanks in advance.

 

[SKATR186]

How old is the fuel? When you run it last ? Plugs, wires, etc. original? I believe that is fuel injected, injectors dirty if its this year you could even hook diagnostics up to it.

Found this link looking around.

http://www.maxumownersclub.com/forum/site_files/manuals/mercruiser/30.pdf

 

[Tski17]

The fuel is fresh and the boat has been run consistently over the last few years... never sitting more than a month between runnings, and in most cases every weekend. I dont think the engine has ever had a tune up, so the plugs, wires and coils are probably still the originals. I am going to have my mechanic hook it up to the diagnostic this week. Im hoping be able to avoid a full tune up, as just poking around on the itnernet it looks like coils will cost me close to $1000 and I cant find wires for this model for less than $500 new.

 

[sim]

B.ring O.ut A.nother T.housand

 

[lcboater]

The fuel is fresh and the boat has been run consistently over the last few years... never sitting more than a month between runnings, and in most cases every weekend. I dont think the engine has ever had a tune up, so the plugs, wires and coils are probably still the originals. I am going to have my mechanic hook it up to the diagnostic this week. Im hoping be able to avoid a full tune up, as just poking around on the itnernet it looks like coils will cost me close to $1000 and I cant find wires for this model for less than $500 new.

You probably won't need coils,at least not all of them.I would start with plugs,go to advance or some auto store because they are the same as a truck.Aroud 7 bucks compared to 20 at merc. Check your wires as you go,i have had wire issues myself,but just made a repair.If you wan't new ,check ebay or Raylar.Change your water sep. filter and you inline filter if it has one(buy it on ebay).Since you don't have alarms it probably isn't setting codes but check if you can.

 

[Philster]

Some questions:

You run in salt?

How old are the risers/manifolds?

Does the engine fire right up on the first crank?

What does the oil look like right now?