starboard engine skips after 20 minutes of use????

[Y Knot]

I just bought a 1995 290 sundancer. it has twin v6's and the starboard one skips. it's doesn't skip all the time, and starts after it runs for about 20 minutes. i put fuel additives and new fuel/water separator....didn't help, i looked at the motor in the dark and didn't see any sparks from the wires or cap...any ideas?

 

[H2ONUT]

Sounds like the electronic pick-up for the rotor on the distributor is bad.

 

[Hampton]

Look inside the Dist Cap. See if it looks coroded. It should be a marine cap which has copper (gold colored) contacts instead of an auto one which has silver-colored contacts, if I remember correctly. Check the air filter. Consider the fuel filter - is that what you replaced?

If no luck, for the most bang/buck ratio, replace spark plugs (number them for future reference), wires, distr cap and rotor.

 

[fwebster]

I'm betting on ignition wires.............

Crank the engine at night in a dark place, look at the wires and watch for the fire works. Bad wires will arc everywhere.

 

[Water U Lookin' At]

Just had a similar problem, and it turned out to be the IAC which made the plugs go bad. I did all the fuel and air replacements too adn nothing helped. So, check the plugs first. If they're covered in carbon, then chances are something is making them go bad. Checking the distributor cap is easy. So, that's a good first thing to check. Then, check the wires AT NIGHT to see if arcing is occurring like Frank said. If none of those items seem to be amiss, then I'm sure it's an IAC. It's $90, and make sure to get the replacement gasket too. It's on top of the engine behind the flame arrestor. Bring a hammer, because with the original part being painted on, it's hard to get off. Good luck and please report back. All of us need to learn from other's experiences.

Eddie

 

[Dave S]

Since the problem occurs after twenty minutes of running it sounds like it may be a "heat soak" issue meaning it takes twenty minutes or so for a component to get hot enough to fail and cause the misfire. It could be things like the coil or the induction pickup in the distributor. But the problem with trying to identify the problem yourself is you will have to start throwing parts at it to see if it stops.

I know you mentioned in your posting that you already checked the wires at night and didn't notice any arcing. On the other hand if the motor has never had plug wires and plugs changed on it recently, it might be prudent to just go ahead and replace them now anyway on both motors especially if they are original. If that doesn't solve the problem then I would have a Merc Tech look at it to see if they can diagnose the cause of the problem.

 

[Y Knot]

thanks for your responses!

i am checking the cap and rotor today. I have been told by a local tech that it's probably going to be the module. i bought a new one and am going to replace that while i'm in there. i'll keep you posted!

thanks again

 

[Y Knot]

it could have been one of two things! it appeared to have a small crack in the cap. i replaced the cap and rotor and checked the module. the module ground was just sitting on a post, i put a nut and secured it. SO FAR IT WORKS GREAT...WE'LL SEE!

THANKS AGAIN.

 

[Hampton]

it could have been one of two things! it appeared to have a small crack in the cap. i replaced the cap and rotor and checked the module. the module ground was just sitting on a post, i put a nut and secured it. SO FAR IT WORKS GREAT...WE'LL SEE!

THANKS AGAIN.

Yeahhhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The ole distr cap and bad spark thingy. I knew it.

 

[top*prop]

tune up..... plugs, wires and cap. modules either work or they dont.