3.0 runs rough after 30 minutes

[clarkstown]

Help! 1987 3.0 runs great for about 30 minutes then acts like water in the tank or fuel being choked off. Plugs are light grey in color. Boat sat for 2 years but had fuel treatment both years and fogged the motor. It has points and condenser which have very few hours on them. Have changed both factory filters and added an inline water separator and nothing makes any significant change. Carb rebuilt on 06 and not run in 07 08. Any ideas?

 

[Rocky_Road]

Re: 3.0 runs rough after 30 minutes

Sounds like your gas tank vent line is restricted...and causing the tank to develop a vacuum as the fuel is being drawn out.

Easy to see if this is the problem...just 'crack' the gas cap (allowing the tank to vent) and running the heck out of the engine for awhile!

Happy boating!

 

[drkaras]

Re: 3.0 runs rough after 30 minutes

Does it sound like my problem?

http://forums.iboats.com/showthread.php?t=344413

 

[clarkstown]

Re: 3.0 runs rough after 30 minutes

Thanks all for the advice. Bought a new coil and will check on the vent line.

 

[greasemonkey1985]

Re: 3.0 runs rough after 30 minutes

hey, have a very similar problem and have done the same things you have checked/done if you could let me know how it goes with the coil because that is my next check/replace. thanks